Configuration Options For Raids; Guidelines For Component Devices - Novell LINUX ENTERPRISE SERVER 10 - STORAGE ADMINISTRATION GUIDE FOR EVMS Administration Manual

6.1.5 Configuration Options for RAIDs

Table 6-5
Option
Spare Disk
Chunk Size (KB)
RAID Level
RAID Algorithm

6.1.6 Guidelines for Component Devices

For efficient use of space and performance, the disks you use to create the RAID should have the
same storage capacity. Typically, if component devices are not of identical storage capacity, then
each member of the RAID uses only an amount of space equal to the capacity of the smallest
member disk.
Version 2.3 and later of mdadm supports component devices up to 4 TB in size each. Earlier
versions support component devices up to 2 TB in size.
IMPORTANT: If you have a local disk, external disk arrays, or SAN devices that are larger than the
supported device size, use a third-party disk partitioner to carve the devices into smaller logical
devices.
You can combine up to 28 component devices to create the RAID array. The md RAID device you
create can be up to the maximum device size supported by the file system you plan to use. For
information about file system limits for SUSE
Support" in the
www.novell.com/documentation/sles10).
56 SLES 10 Storage Administration Guide for EVMS
Configuration Options
Description
For RAIDs 1, 4, and 5, you can optionally specify a device, segment, or
region to use as the replacement for a failed disk (the member device,
segment, or region). On failure, the spare disk automatically replaces the
failed disk, then reconstructs the data.
However, if the parity disk fails on a RAID 5, parity cannot be reconstructed.
For RAIDs 0, 4, or 5, specify the stripe size in KB.
Consider the intended use of the RAID, such as the file system block size,
the applications used, and the actual data (file sizes and typical reads and
writes). A typical write size for large files is 128 KB.
Default: 32 KB
Range: 4 KB to 4096 KB, in powers of 2.
If you selected MD RAID 4/5 Region Manager, specify RAID 4 or RAID 5
(default).
For RAID 5, specify one of the following algorithms to use for striping and
distributing parity on the disk.
Left Asymmetric
Left Symmetric (Default, fastest performance for large reads)
Right Asymmetric
Right Symmetric
SUSE Linux Enterprise Server 10 Installation and Administration Guide. (http://
®
Linux Enterprise Server 10, see "Large File System