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Setting Up RAID Arrays
Example 5-1. Checking the Current State of the Internal Storage Subsystem
# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: ATA
Type:
Host: scsi4 Channel: 00 Id: 00 Lun: 00
Vendor: ATA
Type:
Storage Device Definition
The Linux operating system automatically creates device nodes for all devices in a
system.
Miscellaneous SCSI devices such as scanners are generally mapped as /dev/sg*
devices. Note that the Linux operating system also allows some non-SCSI devices to
be addressable as SCSI pseudo-devices. This can be useful to allow certain SCSI
software packages to work with non-SCSI devices.
Setting Up RAID Arrays
This section discusses the following topics:
''RAID Array
''Creating a RAID-1
''Creating a RAID-0
''Creating and Mounting a File
''Checking the Current State of
RAID Array Overview
RAID is the basis for fault-tolerant file system availability. As disks come in and go out
of service, the only way to keep the file system available is to mirror it on multiple disks
with a disk in each CPU-I/O enclosure.
All of the file systems are created on RAID devices.
The system supports RAID-1 (mirrored) and RAID-0 (striped) on RAID-1. RAID-0 is
configured using RAID-1 devices, since the underlying devices must be fault tolerant.
Each RAID array has a number (for example, /dev/md23) that must be unique among
the running RAID arrays. The RAID array numbers are in the range 0 through 128.
5-8
Express5800/ftServer: System Administrator's Guide for the Linux Operating System
Model: ST380013AS
Direct-Access
Model: ST380013AS
Direct-Access
Overview"
Array"
Array"
System"
RAID"
Rev: 3.00
ANSI SCSI revision: 05
Rev: 3.00
ANSI SCSI revision: 05
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Troubleshooting
