IBM BladeCenter PS703, Technical Overview And Introduction, Page: 86 / 198

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IBM BladeCenter PS703 and PS704 Technical Overview and Introduction
2.9.1 Hardware RAID function
For the PS703, the supported RAID functions are as follows:
򐂰 1 HDD - RAID 0
򐂰 1 SSD - RAID 0
򐂰 2 SSDs - RAID 0, 10
For the PS704, the supported RAID functions are as follows:
򐂰 2 HDDs - RAID 0, 10
򐂰 1 HDD and 1 SSD - RAID 0 on each disk (Combining HDD and SDD is not allowed in
other RAID configurations.)
򐂰 2 SSDs - RAID 0, 10
򐂰 3 SSDs - RAID 0, 5, 10 (RAID 10 on 2 disks; the third disk then can be a hot spare.)
򐂰
4 SSDs - RAID 0, 5, 6, 10 (Hot spare with RAID 5 is possible, that is, 3 disks in RAID 5
and one disk as a hot spare.)
Drives in the PS703 or PS704 blade server can be used to implement and manage various
types of RAID arrays in operating systems that are on the ServerProven list. For the blade
server, you must configure the RAID array through the Disk Array Manager. The AIX Disk
Array Manager is packaged with the Diagnostics utilities on the Diagnostics CD for instances
when the operating system has not been installed yet. Use
smit sasdam to use the AIX Disk
Array Manager to configure the disk drives for use with the SAS controller when there is an
operating system installed. The Disk Array Manager only provides the ability to configure
RAID 0, 5, 6 or 10. To achieve RAID1 mirror functionality use the RAID 10 option with two
internal disk drives.
You can configure a hot spare disk if there are enough disks available. A hot spare is a disk
that can be used by the controller to automatically replace a failed disk in a degraded RAID 5,
6, or 10 disk array. A hot spare disk is useful only if its capacity is greater than or equal to the
capacity of the smallest disk in an array that becomes degraded.
For more information about hot spare disks, see “Using hot spare disks” in the Systems
Hardware Information Center at:
http://publib.boulder.ibm.com/infocenter/powersys/v3r1m5/topic/arebj/sasusinghotsp
aredisks.htm
Note: The SSDs used in the PS703 and PS704 servers are formatted in 528-byte sectors
and are only useable in RAID arrays or as hot spares. Each device contains metadata
written by the onboard 3Gb SAS controller to verify the RAID configuration. Error logs will
exist if problems are encountered. Refer to the appropriate service documentation should
errors occur.
Note: Before you can create a RAID array, you must reformat the drives so that the sector
size of the drives changes from 512 bytes to 528 bytes. If you later decide to remove the
drives, delete the RAID array before you remove the drives. If you decide to delete the
RAID array and reuse the drives, you might need to reformat the drives so that the sector
size of the drives changes from 528 bytes to 512 bytes.