HP P4000 HP Smart Array SAS controllers for Integrity servers support guide - Page 45

Configuration, Planning the RAID configuration, Managing Systems

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3 Configuration This chapter explains how to use the saconfig command to configure Smart Array SAS Controllers. NOTE: Command outputs are similar for different Smart Array SAS controllers, so in most cases the example output is shown for only one controller model. If the difference between controllers is significant for a specific command, separate examples from each controller type are provided. Planning the RAID configuration If you do not know how you want to configure RAID on your system, follow these steps before proceeding to "The saconfig configuration CLI" (page 46): 1. Determine the RAID level you want to use for each logical drive. See "Fault management in supported RAID configurations" (page 24) and "Choosing a RAID method" (page 25). 2. Determine and record the physical disk configuration, and use this to assign disks to logical drives. When you assign disks to logical drives, consider: • Distributing one or more logical drives across controller channels. This protects against a cable disconnection and distributes the I/O load across the channels. You can support different RAID levels across multiple channels. • Using one or more online spare disk drives. Spare drives provide extra protection if there is a disk failure beyond the fault tolerance protection offered by the RAID configuration. Spare drive capacity is held in reserve and is not available except when needed to back up a failed physical drive. 3. Select a stripe size. In most cases, the default stripe size provides the best performance. Use a smaller size only if you know your data is always written in smaller blocks. For RAID 0, 1 and 1+0 the default stripe size is 128 KB. For RAID 5, 50, ADG, and 60, the default stripe size is 16 KB. 4. Determine the logical drive configuration. Consider the following: • Only logical drives can be accessed by HP-UX. Physical disks cannot be accessed by HP-UX. Each logical drive is recognized as a very large SCSI disk. • Do not include physical disks of different capacities in the same logical drive. • HP-UX recognizes Smart Array logical drives as disks, so you can use the LVM to configure them as physical volumes. You can then partition the drive into separate logical volumes. - For more information about LVM for HP-UX 11i v2, see Managing Systems and Workgroups: A Guide for HP-UX System Administrators. - For more information about LVM for HP-UX 11i v3, see HP-UX System Administrator's Guide (volume 3): Logical Volume Management. These documents are available on the HP website at www.hp.com/go/ hpux-core-docs Planning the RAID configuration 45

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3 Configuration
This chapter explains how to use the
saconfig
command to configure Smart Array SAS
Controllers.
NOTE:
Command outputs are similar for different Smart Array SAS controllers, so in most
cases the example output is shown for only one controller model. If the difference between
controllers is significant for a specific command, separate examples from each controller type
are provided.
Planning the RAID configuration
If you do not know how you want to configure RAID on your system, follow these steps before
proceeding to
“The saconfig configuration CLI” (page 46)
:
1.
Determine the RAID level you want to use for each logical drive.
See
“Fault management in supported RAID configurations” (page 24)
and
“Choosing a
RAID method” (page 25)
.
2.
Determine and record the physical disk configuration, and use this to assign disks to logical
drives.
When you assign disks to logical drives, consider:
•
Distributing one or more logical drives across controller channels. This protects against
a cable disconnection and distributes the I/O load across the channels. You can support
different RAID levels across multiple channels.
•
Using one or more online spare disk drives. Spare drives provide extra protection if
there is a disk failure beyond the fault tolerance protection offered by the RAID
configuration. Spare drive capacity is held in reserve and is not available except when
needed to back up a failed physical drive.
3.
Select a stripe size.
In most cases, the default stripe size provides the best performance. Use a smaller size only
if you know your data is always written in smaller blocks.
For RAID 0, 1 and 1+0 the default stripe size is 128 KB. For RAID 5, 50, ADG, and 60, the
default stripe size is 16 KB.
4.
Determine the logical drive configuration. Consider the following:
•
Only logical drives can be accessed by HP-UX. Physical disks cannot be accessed by
HP-UX. Each logical drive is recognized as a very large SCSI disk.
•
Do not include physical disks of different capacities in the same logical drive.
•
HP-UX recognizes Smart Array logical drives as disks, so you can use the LVM to
configure them as physical volumes. You can then partition the drive into separate
logical volumes.
—
For more information about LVM for HP-UX 11i v2, see
Managing Systems and
Workgroups: A Guide for HP-UX System Administrators
.
—
For more information about LVM for HP-UX 11i v3, see
HP-UX System
Administrator's Guide (volume 3): Logical Volume Management
.
These documents are available on the HP website at
www
.hp.com/go/
hpux-core-docs
Planning the RAID configuration
45