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Novell LINUX ENTERPRISE SERVER 11 - STORAGE ADMINISTRATION GUIDE 2-23-2010 Administration Manual

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AUTHORIZED DOCUMENTATION
Storage Administration Guide
Novell
®
SUSE
Linux Enterprise Server
®
11
February 23, 2010
www.novell.com
SLES 11: Storage Administration Guide

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Summary of Contents for Novell LINUX ENTERPRISE SERVER 11 - STORAGE ADMINISTRATION GUIDE 2-23-2010

  • Page 1 AUTHORIZED DOCUMENTATION Storage Administration Guide Novell ® SUSE Linux Enterprise Server ® February 23, 2010 www.novell.com SLES 11: Storage Administration Guide...

  • Page 2: Legal Notices

    Further, Novell, Inc., reserves the right to make changes to any and all parts of Novell software, at any time, without any obligation to notify any person or entity of such changes.
  • Page 3 Novell Trademarks For Novell trademarks, see the Novell Trademark and Service Mark list (http://www.novell.com/company/legal/ trademarks/tmlist.html). Third-Party Materials All third-party trademarks and copyrights are the property of their respective owners.
  • Page 4 SLES 11: Storage Administration Guide...

  • Page 5: Table Of Contents

    Contents About This Guide 1 Overview of File Systems in Linux Terminology ............. . . 13 Major File Systems in Linux .
  • Page 6 5 Resizing File Systems Guidelines for Resizing ............35 5.1.1 File Systems that Support Resizing .
  • Page 7 7.10 Scanning for New Devices without Rebooting ........71 7.11 Scanning for New Partitioned Devices without Rebooting .
  • Page 8 12 iSNS for Linux 12.1 How iSNS Works ............109 12.2 Installing iSNS Server for Linux .
  • Page 9 A.5.1 Managing Multipath I/O ..........138 June 22, 2009 .
  • Page 10 SLES 11: Storage Administration Guide...

  • Page 11: About This Guide

    SUSE Linux Enterprise Server 11 Installation and Administration Guide (http://www.novell.com/documentation/sles11). Documentation Conventions In Novell documentation, a greater-than symbol (>) is used to separate actions within a step and items in a cross-reference path. ® A trademark symbol ( , etc.) denotes a Novell trademark. An asterisk (**) denotes a third-party trademark.
  • Page 12 SLES 11: Storage Administration Guide...

  • Page 13: Overview Of File Systems In Linux

    Overview of File Systems in Linux ® SUSE Linux Enterprise Server ships with a number of different file systems from which to choose, including Ext3, Ext2, ReiserFS, and XFS. Each file system has its own advantages and disadvantages. Professional high-performance setups might require a different choice of file system than a home user’s setup.

  • Page 14: Ext2

    The terms data integrity and data consistency, when used in this section, do not refer to the consistency of the user space data (the data your application writes to its files). Whether this data is consistent must be controlled by the application itself. IMPORTANT: Unless stated otherwise in this section, all the steps required to set up or change partitions and file systems can be performed by using YaST.

  • Page 15: Ext3

    1.2.2 Ext3 Ext3 was designed by Stephen Tweedie. Unlike all other next-generation file systems, Ext3 does not follow a completely new design principle. It is based on Ext2. These two file systems are very closely related to each other. An Ext3 file system can be easily built on top of an Ext2 file system. The most important difference between Ext2 and Ext3 is that Ext3 supports journaling.

  • Page 16: Oracle Cluster File System 2

    This ensures that the Ext3 file system is recognized as such. The change takes effect after the next reboot. 3 To boot a root file system that is set up as an Ext3 partition, include the modules ext3 in the initrd 3a Edit , adding...

  • Page 17: Xfs

    Better Disk Space Utilization In ReiserFS, all data is organized in a structure called a B*-balanced tree. The tree structure contributes to better disk space utilization because small files can be stored directly in the B* tree leaf nodes instead of being stored elsewhere and just maintaining a pointer to the actual disk location.

  • Page 18: Other Supported File Systems

    , the file system originally used by DOS, is today used by various operating systems. ® File system for mounting Novell volumes over networks. ncpfs Network File System: Here, data can be stored on any machine in a network and access might be granted via a network.

  • Page 19: Large File Support In Linux

    However, this limit is still out of reach for the currently available hardware. 1.5 Additional Information File System Primer (http://wiki.novell.com/index.php/File_System_Primer) on the Novell Web site describes a variety of file systems for Linux. It discusses the file systems, why there are so many, and which ones are the best to use for which workloads and data.
  • Page 20 Each of the file system projects described above maintains its own home page on which to find mailing list information, further documentation, and FAQs: E2fsprogs: Ext2/3/4 Filesystem Utilities (http://e2fsprogs.sourceforge.net/) Introducing Ext3 (http://www.ibm.com/developerworks/linux/library/l-fs7.html) ReiserFSprogs (http://chichkin_i.zelnet.ru/namesys/) XFS: A High-Performance Journaling Filesytem (http://oss.sgi.com/projects/xfs/) OCFS2 Project (http://oss.oracle.com/projects/ocfs2/) A comprehensive multipart tutorial about Linux file systems can be found at IBM developerWorks in the...

  • Page 21: What's New

    Storage and Volume Management in SUSE Linux Enterprise (http://www.novell.com/linux/ volumemanagement/strategy.html). For information about managing storage with EVMS2 on SUSE Linux Enterprise Server 10, see the SUSE Linux Enterprise Server 10 SP3: Storage Administration Guide (http://www.novell.com/ documentation/sles10/stor_admin/data/bookinfo.html). 2.2 Ext3 as the Default File System The Ext3 file system has replaced ReiserFS as the default file system recommended by the YaST tools at installation time and when you create file systems.

  • Page 22: Ocfs2 File System Is In The High Availability Release

    2.4 OCFS2 File System Is in the High Availability Release The OCFS2 file system is fully supported as part of the SUSE Linux Enterprise High Availability Extension. 2.5 /dev/disk/by-name Is Deprecated path is deprecated in SUSE Linux Enterprise Server 11 packages. /dev/disk/by-name 2.6 Device Name Persistence in the /dev/disk/by- id Directory...

  • Page 23: User-Friendly Names For Multipathed Devices

    2.8 User-Friendly Names for Multipathed Devices A change in how multipathed device names are handled in the directory (as /dev/disk/by-id described in Section 2.6, “Device Name Persistence in the /dev/disk/by-id Directory,” on page affects your setup for user-friendly names because the two names for the device differ. You must modify the configuration files to scan only the device mapper names after multipathing is configured.
  • Page 24 SLES 11: Storage Administration Guide...

  • Page 25: Planning A Storage Solution

    Planning a Storage Solution Consider what your storage needs are and how you can effectively manage and divide your storage space to best meet your needs. Use the information in this section to help plan your storage ® deployment for file systems on your SUSE Linux Enterprise Server 11 server.

  • Page 26: Open Source Backup

    SLES 11. For a current list of possible backup and antivirus software vendors, see Novell Open Enterprise Server Partner Support: Backup and Antivirus Support (http://www.novell.com/products/ openenterpriseserver/partners_communities.html). This list is updated quarterly. SLES 11: Storage Administration Guide...

  • Page 27: Lvm Configuration

    LVM Configuration This section briefly describes the principles behind Logical Volume Manager (LVM) and its basic features that make it useful under many circumstances. The YaST LVM configuration can be reached from the YaST Expert Partitioner. This partitioning tool enables you to edit and delete existing partitions and create new ones that should be used with LVM.

  • Page 28: Creating Lvm Partitions

    Figure 4-1 compares physical partitioning (left) with LVM segmentation (right). On the left side, one single disk has been divided into three physical partitions (PART), each with a mount point (MP) assigned so that the operating system can access them. On the right side, two disks have been divided into two and three physical partitions each.

  • Page 29: Configuring Physical Volumes

    This value is normally set to 4 MB and allows for a maximum size of 256 GB for physical and logical volumes. The physical extent size should only be increased, for example, to 8, 16, or 32 MB, if you need logical volumes larger than 256 GB. Creating a Volume Group Figure 4-2 4.4 Configuring Physical Volumes...

  • Page 30: Configuring Logical Volumes

    Physical Volume Setup Figure 4-3 To add a previously unassigned partition to the selected volume group, first click the partition, then click Add Volume. At this point, the name of the volume group is entered next to the selected partition. Assign all partitions reserved for LVM to a volume group. Otherwise, the space on the partition remains unused.
  • Page 31 Logical Volume Management Figure 4-4 To create a new logical volume (see Figure 4-5), click Add and fill out the pop-up that opens. For partitioning, specify the size, file system, and mount point. Normally, a file system, such as Reiserfs or Ext2, is created on a logical volume and is then designated a mount point.

  • Page 32: Direct Lvm Management

    Creating Logical Volumes Figure 4-5 If you have already configured LVM on your system, the existing logical volumes can be specified now. Before continuing, assign appropriate mount points to these logical volumes too. Click Next to return to the YaST Expert Partitioner and finish your work there. 4.6 Direct LVM Management If you already have configured LVM and only want to change something, there is an alternative method available.
  • Page 33 To extend the size of a logical volume: 1 Open a terminal console, log in as the user. root 2 If the logical volume contains file systems that are hosted for a virtual machine (such as a Xen VM), shut down the VM. 3 Dismount the file systems on the logical volume.
  • Page 34 SLES 11: Storage Administration Guide...

  • Page 35: Resizing File Systems

    Resizing File Systems When your data needs grow for a volume, you might need to increase the amount of space allocated to its file system. Section 5.1, “Guidelines for Resizing,” on page 35 Section 5.2, “Increasing an Ext2 or Ext3 File System,” on page 36 Section 5.3, “Increasing the Size of a Reiser File System,”...

  • Page 36: Decreasing The Size Of A File System

    When specifying an exact size for the file system, make sure the new size satisfies the following conditions: The new size must be greater than the size of the existing data; otherwise, data loss occurs. The new size must be equal to or less than the current device size because the file system size cannot extend beyond the space available.

  • Page 37: Increasing The Size Of A Reiser File System

    5.3 Increasing the Size of a Reiser File System A ReiserFS file system can be increased in size while mounted or unmounted. 1 Open a terminal console, then log in as the user or equivalent. root 2 Increase the size of the file system on the device called , using one of the following /dev/sda2 methods:...

  • Page 38: Decreasing The Size Of A Reiser File System

    df -h The Disk Free ( ) command shows the total size of the disk, the number of blocks used, and the number of blocks available on the file system. The -h option print sizes in human-readable format, such as 1K, 234M, or 2G. 5.5 Decreasing the Size of a Reiser File System Reiser file systems can be reduced in size only if the volume is unmounted.

  • Page 39: Using Uuids To Mount Devices

    Using UUIDs to Mount Devices This section describes the optional use of UUIDs instead of device names to identify file system devices in the boot loader file and the file. /etc/fstab Section 6.1, “Naming Devices with udev,” on page 39 Section 6.2, “Understanding UUIDs,”...

  • Page 40: Using Uuids To Assemble Or Activate File System Devices

    6.2.1 Using UUIDs to Assemble or Activate File System Devices The UUID is always unique to the partition and does not depend on the order in which it appears or where it is mounted. With certain SAN devices attached to the server, the system partitions are renamed and moved to be the last device.

  • Page 41: Using Uuids In The Boot Loader And /Etc/Fstab File (Ia64)

    For example, change kernel /boot/vmlinuz root=/dev/sda1 kernel /boot/vmlinuz root=/dev/disk/by-uuid/e014e482-1c2d-4d09-84ec- 61b3aefde77a IMPORTANT: If you make a mistake, you can boot the server without the SAN connected, and fix the error by using the backup copy of the file as a guide. /boot/grub/menu.1st If you use the Boot Loader option in YaST, there is a defect where it adds some duplicate lines to the boot loader file when you change a value.

  • Page 42: Additional Information

    IMPORTANT: Do not leave stray characters or spaces in the file. 6.5 Additional Information For more information about using for managing devices, see “Dynamic Kernel Device udev(8) Management with udev” (http://www.novell.com/documentation/sles11/sles_admin/data/ ® cha_udev.html) in the SUSE Linux Enterprise Server 11 Installation and Administration Guide. For more information about commands, see its man page.

  • Page 43: Managing Multipath I/O For Devices

    Managing Multipath I/O for Devices This section describes how to manage failover and path load balancing for multiple paths between the servers and block storage devices. Section 7.1, “Understanding Multipathing,” on page 43 Section 7.2, “Planning for Multipathing,” on page 44 Section 7.3, “Multipath Management Tools,”...

  • Page 44: Planning For Multipathing

    Typical connection problems involve faulty adapters, cables, or controllers. When you configure multipath I/O for a device, the multipath driver monitors the active connection between devices. When the multipath driver detects I/O errors for an active path, it fails over the traffic to the device’s designated secondary path.

  • Page 45: Using Multipathed Devices

    Disk Management Tasks Perform the following disk management tasks before you attempt to configure multipathing for a physical or logical device that has multiple paths: Use third-party tools to carve physical disks into smaller logical disks. Use third-party tools to partition physical or logical disks. If you change the partitioning in the running system, the Device Mapper Multipath (DM-MP) module does not automatically detect and reflect these changes.

  • Page 46: Using Lvm2 On Multipath Devices

    7.2.3 Using LVM2 on Multipath Devices By default, LVM2 does not recognize multipathed devices. To make LVM2 recognize the multipathed devices as possible physical volumes, you must modify . It is /etc/lvm/lvm.conf important to modify it so that it does not scan and use the physical paths, but only accesses the multipath I/O storage through the multipath I/O layer.

  • Page 47: Partitioning Multipath Devices

    7.2.6 Partitioning Multipath Devices Behavior changes for how multipathed devices are handled might affect your configuration if you are upgrading. “SUSE Linux Enterprise Server 11” on page 47 “SUSE Linux Enterprise Server 10” on page 47 “SUSE Linux Enterprise Server 9” on page 47 SUSE Linux Enterprise Server 11 In SUSE Linux Enterprise Server 11, the default multipath setup relies on to overwrite the...
  • Page 48 “Tested Storage Arrays for Multipathing Support” on page 49 “Storage Arrays that Require Specific Hardware Handlers” on page 49 Storage Arrays That Are Automatically Detected for Multipathing package automatically detects the following storage arrays: multipath-tools 3PARdata VV Compaq* HSV110 Compaq MSA1000 DDN SAN MultiDirector DEC* HSG80 EMC* CLARiiON* CX...
  • Page 49 Consider the following caveats: Not all of the storage arrays that are automatically detected have been tested on SUSE Linux Enterprise Server. For information, see “Tested Storage Arrays for Multipathing Support” on page Some storage arrays might require specific hardware handlers. A hardware handler is a kernel module that performs hardware-specific actions when switching path groups and dealing with I/O errors.

  • Page 50: Multipath Management Tools

    DM-MP is the preferred solution for multipathing on SUSE Linux Enterprise Server 11. It is the ® only multipathing option shipped with the product that is completely supported by Novell SUSE. DM-MP features automatic configuration of the multipathing subsystem for a large variety of setups.

  • Page 51: Multipath I/O Management Tools

    Multipath I/O Features of Storage Arrays Table 7-1 Features of Storage Arrays Description Active/passive controllers One controller is active and serves all LUNs. The second controller acts as a standby. The second controller also presents the LUNs to the multipath component so that the operating system knows about redundant paths.

  • Page 52: Using Mdadm For Multipathed Devices

    For a list of files included in this package, see the multipath-tools Package Description (http:// www.novell.com/products/linuxpackages/suselinux/multipath-tools.html). 1 Ensure that the package is installed by entering the following at a terminal...

  • Page 53: The Linux Multipath(8) Command

    For information about modifying the file, see Section 7.2.3, “Using LVM2 on /etc/lvm/lvm.conf Multipath Devices,” on page 7.3.4 The Linux multipath(8) Command Use the Linux command to configure and manage multipathed devices. multipath(8) General syntax for the command: multipath(8) multipath [-v verbosity] [-d] [-h|-l|-ll|-f|-F] [-p failover | multibus | group_by_serial | group_by_prio| group_by_node_name ] General Examples Configure multipath devices:...

  • Page 54: Configuring The System For Multipathing

    multipath -p [failover|multibus|group_by_serial|group_by_prio|group_by_node_name] Specify one of the group policy options that are described in Table 7-3: Group Policy Options for the multipath -p Command Table 7-3 Policy Option Description failover One path per priority group. You can use only one path at a time. multibus All paths in one priority group.

  • Page 55: Partitioning Multipathed Devices

    SCSI device scanning behavior, such as to indicate that LUNs are not numbered consecutively. For information, see Options for SCSI Device Scanning (http://support.novell.com/techcenter/sdb/en/2005/06/drahn_scsi_scanning.html) in the Novell Support Knowledgebase. 7.4.2 Partitioning Multipathed Devices Partitioning devices that have multiple paths is not recommended, but it is supported.

  • Page 56: Adding Multipathd To The Boot Sequence

    After changing , you must re-create the on your system with the /etc/sysconfig/kernel INITRD command, then reboot in order for the changes to take effect. mkinitrd When you are using LILO as a boot manager, reinstall it with the command. No further /sbin/lilo action is required if you are using GRUB.
  • Page 57 Creating the multipath.conf File If the file does not exist, copy the example to create the file: /etc/multipath.conf 1 In a terminal console, log in as the user. root 2 Enter the following command (all on one line, of course) to copy the template: cp /usr/share/doc/packages/multipath-tools/multipath.conf.synthetic /etc/ multipath.conf 3 Use the...
  • Page 58 Configuring User-Friendly Names or Alias Names in /etc/multipath.conf A multipath device can be identified by either its WWID or an alias that you assign for it. The WWID (Worldwide Identifier) is an identifier for the multipath device that is guaranteed to be globally unique and unchanging.
  • Page 59 NOTE: The keyword devnode_blacklist has been deprecated and replaced with the keyword blacklist. For example, to blacklist local devices and all arrays from the driver from being managed by cciss multipath, the section looks like this: blacklist blacklist { wwid 26353900f02796769 devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st|sda)[0-9]*"...

  • Page 60: Enabling And Starting Multipath I/O Services

    defaults { dev_loss_tmo 90 fast_io_fail_tmo 5 The dev_loss_tmo parameter sets the number of seconds to wait before marking a multipath link as bad. When the path fails, any current I/O on that failed path fails. The default value varies according to the device driver being used.

  • Page 61: Configuring Path Failover Policies And Priorities

    7.6 Configuring Path Failover Policies and Priorities In a Linux host, when there are multiple paths to a storage controller, each path appears as a separate block device, and results in multiple block devices for single LUN. The Device Mapper Multipath service detects multiple paths with the same LUN ID, and creates a new multipath device with that ID.
  • Page 62 “Configuring for Single Path Failover” on page 66 “Grouping I/O Paths for Round-Robin Load Balancing” on page 66 Understanding Priority Groups and Attributes A priority group is a collection of paths that go to the same physical LUN. By default, I/O is distributed in a round-robin fashion across all paths in the group.
  • Page 63 Multipath Attribute Description Values path_grouping_policy Specifies the path grouping failover: One path is assigned per priority group policy for a multipath device so that only one path at a time is used. hosted by a given controller. multibus: (Default) All valid paths are in one priority group.
  • Page 64 Multipath Attribute Description Values path_selector Specifies the path-selector round-robin 0: (Default) The load-balancing algorithm to use for load algorithm used to balance traffic across all active balancing. paths in a priority group. Beginning in SUSE Linux Enterprise Server 11, the following additional I/O balancing options are available: least-pending: Provides a least-pending-I/O dynamic load balancing policy for bio based...
  • Page 65 Multipath Attribute Description Values prio_callout Specifies the program and If no attribute is used, all paths prio_callout arguments to use to are equal. This is the default. Multipath prio_callouts determine the layout of the are located in shared /bin/true: Use this value when the multipath map.
  • Page 66 Multipath Attribute Description Values rr_min_io Specifies the number of I/O n (>0): Specify an integer value greater than 0. transactions to route to a path 1000: Default. before switching to the next path in the same path group, as determined by the specified algorithm in the setting.

  • Page 67: Using A Script To Set Path Priorities

    7.6.3 Using a Script to Set Path Priorities You can create a script that interacts with Device Mapper - Multipath (DM-MP) to provide priorities for paths to the LUN when set as a resource for the setting. prio_callout First, set up a text file that lists information about each device and the priority values you want to assign to each path.
  • Page 68 “Options” on page 68 “Return Values” on page 68 Syntax mpath_prio_alua [-d directory] [-h] [-v] [-V] device [device...] Prerequisite SCSI devices Options -d directory Specifyies the Linux directory path where the listed device node names can be found. The default directory is .

  • Page 69: Reporting Target Path Groups

    Priority Value Description The device is in the standby group. All other groups. Values are widely spaced because of the way the command handles them. It multiplies multipath the number of paths in a group with the priority value for the group, then selects the group with the highest result.

  • Page 70: Configuring Multipath I/O For An Existing Software Raid

    3 After installation, add dm-multipath /etc/sysconfig/kernel:INITRD_MODULES 4 For System Z, before running mkinitrd, edit the file to change the by-path /etc/zipl.conf information in with the same by-id information that was used in the / zipl.conf etc/fstab 5 Re-run to update the image.

  • Page 71: Scanning For New Devices Without Rebooting

    5 After the multipathing services are started, verify that the software RAID’s component devices are listed in the directory. Do one of the following: /dev/disk/by-id Devices Are Listed: The device names should now have symbolic links to their Device Mapper Multipath device names, such as /dev/dm-1 Devices Are Not Listed: Force the multipath service to recognize them by flushing and rediscovering the devices.
  • Page 72 Options For most storage subsystems, the script can be run successfully without options. However, some special cases might need to use one or more of the following parameters for the rescan-scsi- script: bus.sh Option Description Activates scanning for LUNs 0-7. [Default: 0] Activates scanning for LUNs 0 to NUM.

  • Page 73: Scanning For New Partitioned Devices Without Rebooting

    rescan-scsi-bus.sh [options] 3 Check for scanning progress in the system log (the file). At a terminal /var/log/messages console prompt, enter tail -30 /var/log/messages This command displays the last 30 lines of the log. For example: # tail -30 /var/log/messages . . . Feb 14 01:03 kernel: SCSI device sde: 81920000 Feb 14 01:03 kernel: SCSI device sdf: 81920000 Feb 14 01:03 multipathd: sde: path checker registered...

  • Page 74: Viewing Multipath I/O Status

    mke2fs -j /dev/dm-9 tune2fs -L oradata3 /dev/dm-9 9 Restart DM-MP to let it read the aliases by entering /etc/init.d/multipathd restart 10 Verify that the device is recognized by by entering multipathd multipath -ll 11 Use a text editor to add a mount entry in the file.

  • Page 75: Managing I/O In Error Situations

    Whether the group is the first (highest priority) group Paths contained within the group The following information is displayed for each path: The physical address as host:bus:target:lun, such as 1:0:1:2 Device node name, such as Major:minor numbers Status of the device 7.13 Managing I/O in Error Situations You might need to configure multipathing to queue I/O if all paths fail concurrently by enabling queue_if_no_path.

  • Page 76: Resolving Stalled I/O

    0 queue_if_no_path 7.15 Additional Information For more information about configuring and using multipath I/O on SUSE Linux Enterprise Server, see the following additional resources in the Novell Support Knowledgebase: How to Setup/Use Multipathing on SLES (http://support.novell.com/techcenter/sdb/en/2005/ 04/sles_multipathing.html) Troubleshooting SLES Multipathing (MPIO) Problems (Technical Information Document 3231766) (http://www.novell.com/support/...

  • Page 77: What's Next

    7.16 What’s Next If you want to use software RAIDs, create and configure them before you create file systems on the devices. For information, see the following: Chapter 8, “Software RAID Configuration,” on page 79 Chapter 10, “Managing Software RAIDs 6 and 10 with mdadm,” on page 89 Managing Multipath I/O for Devices...
  • Page 78 SLES 11: Storage Administration Guide...

  • Page 79: Software Raid Configuration

    Software RAID Configuration The purpose of RAID (redundant array of independent disks) is to combine several hard disk partitions into one large virtual hard disk to optimize performance, data security, or both. Most RAID controllers use the SCSI protocol because it can address a larger number of hard disks in a more effective way than the IDE protocol and is more suitable for parallel processing of commands.

  • Page 80: Raid 1

    8.1.2 RAID 1 This level provides adequate security for your data, because the data is copied to another hard disk 1:1. This is known as hard disk mirroring. If a disk is destroyed, a copy of its contents is available on another mirrored disk.
  • Page 81 the same amount of space as the smallest sized partition. The RAID partitions should be stored on different hard disks to decrease the risk of losing data if one is defective (RAID 1 and 5) and to optimize the performance of RAID 0. After creating all the partitions to use with RAID, click RAID >...

  • Page 82: Troubleshooting

    File System Settings Figure 8-2 As with conventional partitioning, set the file system to use as well as encryption and the mount point for the RAID volume. After completing the configuration with Finish, see the /dev/md0 device and others indicated with RAID in the Expert Partitioner. 8.3 Troubleshooting Check the file to find out whether a RAID partition has been damaged.

  • Page 83: Configuring Software Raid For The Root Partition

    Configuring Software RAID for the Root Partition ® In SUSE Linux Enterprise Server 11, the Device Mapper RAID tool has been integrated into the YaST Partitioner. You can use the partitioner at install time to create a software RAID for the system device that contains your root ( ) partition.

  • Page 84: Enabling Multipath I/O Support At Install Time

    3 On the Expert Partitioner page, expand Hard Disks in the System View panel to view the default proposal. 4 On the Hard Disks page, select Configure > Configure iSCSI, then click Continue when prompted to continue with initializing the iSCSI initiator configuration. 9.3 Enabling Multipath I/O Support at Install Time If there are multiple I/O paths to the devices you want to use to create a software RAID device for the root (/) partition, you must enable multipath support before you create the software RAID...
  • Page 85 5c Under New Partition Size, specify to use the maximum size, then click Next. 5d Under Format Options, select Do not format partition, then select 0xFD Linux RAID from the drop-down list. 5e Under Mount Options, select Do not mount partition. 5f Click Finish.
  • Page 86 6d Click Next. 6e Under RAID Options, select the chunk size from the drop-down list. The default chunk size for a RAID 1 (Mirroring) is 4 KB. The default chunk size for a RAID 0 (Striping) is 32 KB. Available chunk sizes are 4 KB, 8 KB, 16 KB, 32 KB, 64 KB, 128 KB, 256 KB, 512 KB, 1 MB, 2 MB, or 4 MB.
  • Page 87 The software RAID device is managed by Device Mapper, and creates a device under the path. /dev/md0 7 On the Expert Partitioner page, click Accept. The new proposal appears under Partitioning on the Installation Settings page. For example, the setup for the 8 Continue with the install.
  • Page 88 SLES 11: Storage Administration Guide...

  • Page 89: Managing Software Raids 6 And 10 With Mdadm

    Managing Software RAIDs 6 and 10 with mdadm This section describes how to create software RAID 6 and 10 devices, using the Multiple Devices Administration ( ) tool. You can also use to create RAIDs 0, 1, 4, and 5. The mdadm(8) mdadm mdadm...

  • Page 90: Creating A Raid 6

    10.1.2 Creating a RAID 6 The procedure in this section creates a RAID 6 device with four devices: /dev/md0 /dev/sda1 , and . Make sure to modify the procedure to use your actual dev/sdb1 /dev/sdc1 /dev/sdd1 device nodes. 1 Open a terminal console, then log in as the user or equivalent.

  • Page 91: Creating Nested Raid 10 (1+0) With Mdadm

    The following table describes the advantages and disadvantages of RAID 10 nesting as 1+0 versus 0+1. It assumes that the storage objects you use reside on different disks, each with a dedicated I/O capability. Nested RAID Levels Table 10-2 RAID Level Description Performance and Fault Tolerance 10 (1+0) RAID 0 (stripe)

  • Page 92: Creating Nested Raid 10 (0+1) With Mdadm

    Scenario for Creating a RAID 10 (1+0) by Nesting Table 10-3 Raw Devices RAID 1 (mirror) RAID 1+0 (striped mirrors) /dev/sdb1 /dev/md0 /dev/sdc1 /dev/md2 /dev/sdd1 /dev/md1 /dev/sde1 1 Open a terminal console, then log in as the user or equivalent. root 2 Create 2 software RAID 1 devices, using two different devices for each RAID 1 device.

  • Page 93: Creating A Complex Raid 10 With Mdadm

    Scenario for Creating a RAID 10 (0+1) by Nesting Table 10-4 Raw Devices RAID 0 (stripe) RAID 0+1 (mirrored stripes) /dev/sdb1 /dev/md0 /dev/sdc1 /dev/md2 /dev/sdd1 /dev/md1 /dev/sde1 1 Open a terminal console, then log in as the root user or equivalent. 2 Create two software RAID 0 devices, using two different devices for each RAID 0 device.
  • Page 94 “Near Layout” on page 95 “Far Layout” on page 95 Comparing the Complex RAID10 and Nested RAID 10 (1+0) The complex RAID 10 is similar in purpose to a nested RAID 10 (1+0), but differs in the following ways: Complex vs. Nested RAID 10 Table 10-5 Feature mdadm RAID10 Option...
  • Page 95 Near Layout With the near layout, copies of a block of data are striped near each other on different component devices. That is, multiple copies of one data block are at similar offsets in different devices. Near is the default layout for RAID10. For example, if you use an odd number of component devices and two copies of data, some copies are perhaps one chunk further into the device.

  • Page 96: Creating A Raid 10 With Mdadm

    sda1 sdb1 sdc1 sde1 sdf1 . . . 10.3.2 Creating a RAID 10 with mdadm The RAID10 option for creates a RAID 10 device without nesting. For information about mdadm RAID10-, see Section 10.3, “Creating a Complex RAID 10 with mdadm,” on page The procedure in this section uses the device names shown in the following table.
  • Page 97 RAID Type Allowable Number of Slots Missing RAID 1 All but one device RAID 4 One slot RAID 5 One slot RAID 6 One or two slots To create a degraded array in which some devices are missing, simply give the word missing place of a device name.
  • Page 98 SLES 11: Storage Administration Guide...

  • Page 99: Resizing Software Raid Arrays With Mdadm

    Resizing Software RAID Arrays with mdadm This section describes how to increase or reduce the size of a software RAID 1, 4, 5, or 6 device with the Multiple Device Administration ( ) tool. mdadm(8) WARNING: Before starting any of the tasks described in this section, make sure that you have a valid backup of all of the data.

  • Page 100: Increasing The Size Of A Software Raid

    11.1.2 Overview of Tasks Resizing the RAID involves the following tasks. The order in which these tasks is performed depends on whether you are increasing or decreasing its size. Tasks Involved in Resizing a RAID Table 11-2 Order If Order If Tasks Description Increasing...

  • Page 101: Increasing The Size Of The Raid Array

    Scenario for Increasing the Size of Component Partitions Table 11-3 RAID Device Component Partitions /dev/md0 /dev/sda1 /dev/sdb1 /dev/sdc1 To increase the size of the component partitions for the RAID: 1 Open a terminal console, then log in as the user or equivalent. root 2 Make sure that the RAID array is consistent and synchronized by entering cat /proc/mdstat...

  • Page 102: Increasing The Size Of The File System

    The procedure in this section uses the device name for the RAID device. Make sure to /dev/md0 modify the name to use the name of your own device. 1 Open a terminal console, then log in as the user or equivalent. root 2 Check the size of the array and the device size known to the array by entering mdadm -D /dev/md0 | grep -e "Array Size"...
  • Page 103 resize2fs /dev/md0 size The size parameter specifies the requested new size of the file system. If no units are specified, the unit of the size parameter is the block size of the file system. Optionally, the size parameter can be suffixed by one of the following the unit designators: s for 512 byte sectors;...

  • Page 104: Decreasing The Size Of A Software Raid

    11.3 Decreasing the Size of a Software RAID Before you begin, review the guidelines in Section 11.1, “Understanding the Resizing Process,” on page Section 11.3.1, “Decreasing the Size of the File System,” on page 104 Section 11.3.2, “Decreasing the Size of Component Partitions,” on page 105 Section 11.3.3, “Decreasing the Size of the RAID Array,”...

  • Page 105: Decreasing The Size Of Component Partitions

    umount /mnt/point If the partition you are attempting to decrease in size contains system files (such as the root ( volume), unmounting is possible only when booting from a bootable CD or floppy. 3 Decrease the size of the file system on the software RAID device called by entering /dev/md0 resize_reiserfs -s size /dev/md0...

  • Page 106: Decreasing The Size Of The Raid Array

    cat /proc/mdstat If your RAID array is still synchronizing according to the output of this command, you must wait until synchronization is complete before continuing. 3 Remove one of the component partitions from the RAID array. For example, to remove /dev/ , enter sda1...
  • Page 107 mdadm -D /dev/md0 | grep -e "Array Size" -e "Device Size" 5 Do one of the following: If your array was successfully resized, you are done. If your array was not resized as you expected, you must reboot, then try this procedure again.
  • Page 108 108 SLES 11: Storage Administration Guide...

  • Page 109: Isns For Linux

    iSNS for Linux Storage area networks (SANs) can contain many disk drives that are dispersed across complex networks. This can make device discovery and device ownership difficult. iSCSI initiators must be able to identify storage resources in the SAN and determine whether they have access to them. Internet Storage Name Service (iSNS) is a standards-based service that is available beginning with ®...

  • Page 110: Installing Isns Server For Linux

    iSNS Discovery Domains and Discovery Domain Sets Figure 12-1 Both iSCSI targets and iSCSI initiators use iSNS clients to initiate transactions with iSNS servers by using the iSNS protocol. They then register device attribute information in a common discovery domain, download information about other registered clients, and receive asynchronous notification of events that occur in their discovery domain.
  • Page 111 To install iSNS for Linux: 1 Start YaST and select Network Services > iSNS Server. 2 When prompted to install the package, click Install. isns 3 Follow the install dialog instructions to provide the SUSE Linux Enterprise Server 11 installation disks. When the installation is complete, the iSNS Service configuration dialog opens automatically to the Service tab.

  • Page 112: Configuring Isns Discovery Domains

    12.3 Configuring iSNS Discovery Domains In order for iSCSI initiators and targets to use the iSNS service, they must belong to a discovery domain. IMPORTANT: The SNS service must be installed and running to configure iSNS discovery domains. For information, see Section 12.4, “Starting iSNS,”...

  • Page 113: Creating Isns Discovery Domain Sets

    3 Click the Create Discovery Domain button. You can also select an existing discovery domain and click the Delete button to remove that discovery domain. 4 Specify the name of the discovery domain you are creating, then click OK. 5 Continue with Section 12.3.2, “Creating iSNS Discovery Domain Sets,”...

  • Page 114: Adding Iscsi Nodes To A Discovery Domain

    The Discovery Domain Set Members area lists all discovery domains that are assigned to a selected discovery domain set. Selecting a different discovery domain set refreshes the list with members from that discovery domain set. You can add and delete discovery domains from a selected discovery domain set.

  • Page 115: Adding Discovery Domains To A Discovery Domain Set

    3 Review the list of nodes to make sure that the iSCSI targets and initiators that you want to use the iSNS service are listed. If an iSCSI target or initiator is not listed, you might need to restart the iSCSI service on the node.

  • Page 116: Starting Isns

    2 Click the Discovery Domains Set tab. 3 Select Create Discovery Domain Set to add a new set to the list of discovery domain sets. 4 Choose a discovery domain set to modify. 5 Click Add Discovery Domain, select the discovery domain you want to add to the discovery domain set, then click Add Discovery Domain.

  • Page 117: Mass Storage Over Ip Networks: Iscsi

    Mass Storage over IP Networks: iSCSI One of the central tasks in computer centers and when operating servers is providing hard disk capacity for server systems. Fibre Channel is often used for this purpose. iSCSI (Internet SCSI) solutions provide a lower-cost alternative to Fibre Channel that can leverage commodity servers and Ethernet networking equipment.

  • Page 118: Installing Iscsi

    Many storage solutions provide access over iSCSI, but it is also possible to run a Linux server that provides an iSCSI target. In this case, it is important to set up a Linux server that is optimized for file system services. The iSCSI target accesses block devices in Linux. Therefore, it is possible to use RAID solutions to increase disk space as well as a lot of memory to improve data caching.

  • Page 119: Setting Up An Iscsi Target

    13.2 Setting Up an iSCSI Target ® SUSE Linux Enterprise Server comes with an open source iSCSI target solution that evolved from the Ardis iSCSI target. A basic setup can be done with YaST, but to take full advantage of iSCSI, a manual setup is required.

  • Page 120: Creating Iscsi Targets With Yast

    each virtual disk from a physical disk or a partition. After you set up the virtual disks for the guest virtual machine, start the guest server, then configure the new blank virtual disks as iSCSI target devices by following the same process as for a physical server. File-baked disk images are created on the Xen host server, then assigned to the Xen guest server.
  • Page 121 7c Click Add to add a new iSCSI target. The iSCSI target automatically presents an unformatted partition or block device and completes the Target and Identifier fields. 7d You can accept this, or browse to select a different space. You can also subdivide the space to create LUNs on the device by clicking Add and specifying sectors to allocate to that LUN.

  • Page 122: Configuring An Iscsi Target Manually

    The next menu configures the access restrictions of the target. The configuration is very similar to the configuration of the discovery authentication. In this case, at least an incoming authentication should be setup. Next finishes the configuration of the new target, and brings you back to the overview page of the Target tab.

  • Page 123: Configuring Online Targets With Ietadm

    cat /proc/net/iet/volume tid:1 name:iqn.2006-02.com.example.iserv:systems lun:0 state:0 iotype:fileio path:/dev/mapper/system-v3 lun:1 state:0 iotype:fileio path:/dev/hda4 lun:2 state:0 iotype:fileio path:/var/lib/xen/images/xen-1 There are many more options that control the behavior of the iSCSI target. For more information, see the man page of ietd.conf Active sessions are also displayed in the file system.

  • Page 124: Configuring Iscsi Initiator

    ietadm can also be used to change various configuration parameters. Obtain a list of the global variables with . The output looks like: ietadm --op show --tid=1 --sid=0 InitialR2T=Yes ImmediateData=Yes MaxConnections=1 MaxRecvDataSegmentLength=8192 MaxXmitDataSegmentLength=8192 MaxBurstLength=262144 FirstBurstLength=65536 DefaultTime2Wait=2 DefaultTime2Retain=20 MaxOutstandingR2T=1 DataPDUInOrder=Yes DataSequenceInOrder=Yes ErrorRecoveryLevel=0 HeaderDigest=None DataDigest=None...

  • Page 125: Using Yast For The Iscsi Initiator Configuration

    13.3.1 Using YaST for the iSCSI Initiator Configuration The iSCSI Initiator Overview in YaST is divided into three tabs: Service: The Service tab can be used to enable the iSCSI initiator at boot time. It also offers to set a unique Initiator Name and an iSNS server to use for the discovery. The default port for iSNS is 3205.
  • Page 126 If the server has iBFT (iSCSI Boot Firmware Table) support, the Initiator Name is completed with the corresponding value in the IBFT, and you are not able to change the initiator name in this interface. Use the BIOS Setup to modify it instead.The iBFT is a block of information containing various parameters useful to the iSCSI boot process, including iSCSI target and initiator descriptions for the server.

  • Page 127: Setting Up The Iscsi Initiator Manually

    Setting the Start-up Preference for iSCSI Target Devices 1 In YaST, select iSCSI Initiator, then select the Connected Targets tab to view a list of the iSCSI target devices that are currently connected to the server. 2 Select the iSCSI target device that you want to manage. 3 Click Toggle Start-Up to modify the setting: Automatic: This option is used for iSCSI targets that are to be connected when the iSCSI service itself starts up.This is the typical configuration.
  • Page 128 the discovery or from the node database. Do this with the parameters -m discovery -m node . Using just with one of these parameters gives an overview of the stored iscsiadm iscsiadm records: iscsiadm -m discovery 149.44.171.99:3260,1 iqn.2006-02.com.example.iserv:systems The target name in this example is .

  • Page 129: For More Information

    Important pages for more information about open-iscsi are: Open-iSCSI Project (http://www.open-iscsi.org/) AppNote: iFolder on Open Enterprise Server Linux Cluster using iSCSI (http:// www.novell.com/coolsolutions/appnote/15394.html) There is also some online documentation available. See the man pages for iscsiadm iscsid...
  • Page 130 130 SLES 11: Storage Administration Guide...

  • Page 131: Understanding Volume Snapshots

    Volume Snapshots A file system snapshot is a copy-on-write technology that monitors changes to an existing volume’s data blocks so that when a write is made to one of the blocks, the block’s value at the snapshot time is copied to a snapshot volume. In this way, a point-in-time copy of the data is preserved until the snapshot volume is deleted.

  • Page 132: Creating Linux Snapshots With Lvm

    14.2 Creating Linux Snapshots with LVM The Logical Volume Manager (LVM) can be used for creating snapshots of your file system. 1 Open a terminal console, log in as the user, then enter root lvcreate -s -L 1G -n snap_volume source_volume_path For example: lvcreate -s -L 1G -n linux01-snap /dev/lvm/linux01 The snapshot is created as the...

  • Page 133: Troubleshooting Storage Issues

    Troubleshooting Storage Issues This section describes how to work around known issues for devices, software RAIDs, multipath I/ O, and volumes. Section 15.1, “Is DM-MPIO Available for the Boot Partition?,” on page 133 15.1 Is DM-MPIO Available for the Boot Partition? ®...
  • Page 134 134 SLES 11: Storage Administration Guide...

  • Page 135: February 23, 2010

    Documentation Updates This section contains information about documentation content changes made to the SUSE Linux ® Enterprise Server Storage Administration Guide since the initial release of SUSE Linux Enterprise Server 11. If you are an existing user, review the change entries to readily identify modified content. If you are a new user, simply read the guide in its current state.

  • Page 136: January 20, 2010

    A.2 January 20, 2010 Updates were made to the following section. The changes are explained below. Section A.2.1, “Managing Multipath I/O,” on page 136 A.2.1 Managing Multipath I/O Location Change “Configuring Default Multipath Behavior In the command line, use the path default_getuid in /etc/multipath.conf”...

  • Page 137: Resizing File Systems

    A.3.2 Resizing File Systems The following changes were made to this section: Location Change Section 5.1.1, “File Systems that Support The resize2fs utility supports online or offline resizing for the Resizing,” on page 35 ext3 file system. A.3.3 What’s New The following change was made to this section: Location Change...

  • Page 138: What's New

    Location Change “Configuring Default Multipath Behavior Changed getuid_callout to getuid. in /etc/multipath.conf” on page 59 “Understanding Priority Groups and Changed getuid_callout to getuid. Attributes” on page 62 “path_selector” on page 64 Added descriptions of least-pending, length-load-balancing, and service-time options. A.4.3 What’s New The following change was made to this section: Location Change...

  • Page 139: Managing Software Raids 6 And 10 With Mdadm

    Location Change Section 7.8, “Configuring Multipath I/O Added Step 4 on page 70 Step 6 on page 70 for System for the Root Device,” on page 69 Section 7.11, “Scanning for New Corrected the syntax for the command lines in Step 2. Partitioned Devices without Rebooting,”...

  • Page 140: Managing Multipath I/O

    A.7.1 Managing Multipath I/O The following changes were made to this section: Location Change “Storage Arrays That Are Automatically Testing of the IBM zSeries* device with multipathing has Detected for Multipathing” on page 48 shown that the dev_loss_tmo parameter should be set to 90 seconds, and the fast_io_fail_tmo parameter should be set to 5 seconds.

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