IBM SAS RAID controllers, Manual

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The following information provides data redundancy, usable disk capacity, read performance, and write
performance for each RAID level.
Table 6. RAID level summary
RAID level Data redundancy
Usable disk
capacity
Read performance Write performance
Devices per array
on PCI-X and PCIe
adapters Devices per array
on PCIe2 and
PCIe3 adapters
RAID 5 Very good 67% - 94% Very good Good Minimum: 3
Maximum: 18
Minimum: 3
Maximum: 32
RAID 6 Excellent 50% - 89% Very good Fair to good Minimum: 4
Maximum: 18
Minimum: 4
Maximum: 32
System mirroring Excellent 50% Excellent Very good Not applicable Not applicable
RAID 5
Creates array parity information so that the data can be reconstructed if a disk in the array fails.
This level provides better capacity than System Mirroring but possibly lower performance.
RAID 6
Creates array "P" and "Q" parity information so that the data can be reconstructed if one or two
disks in the array fail. This level provides better data redundancy than RAID 5 but with slightly
lower capacity and possibly lower performance. It also provides better capacity than System
Mirroring but possibly lower performance.
System mirroring
Stores data redundantly on mirrored pairs to provide maximum protection against disk failures.
This level provides better performance than RAID 5 or RAID 6, but has lower capacity.
Controller software
For the adapter to be identified and configured by IBM i, the requisite software support must be
installed. The requisite software for the adapter is often preinstalled during IBM i installation.
It might be necessary to perform operations related to the installation, verification, and maintenance of
the IBM i software support for the adapter.
Software for the adapter is packaged in Program Temporary Fix (PTF) format and distributed as part of
the base IBM i installation media, cumulative package media, and through the Web-based Fix Delivery
Center for IBM i. This information is an overview of the IBM i software support that is required for the
adapter. For complete information related to the installation and maintenance of IBM i, see the IBM
System i
®
and IBM i Information Center website.
The adapter runs onboard microcode. Although a version of adapter microcode might be distributed
along with the IBM i, this does not necessarily represent the most recent version of microcode that is
available for the adapter. Newer PTFs might be available for the most current level of adapter microcode.
Contact your technical support to verify the latest PTFs available for your specific adapters.
For the latest PTF group, HIPER (High Impact PERvasive) PTF, and cumulative PTF packages for your
release, see Fix Central.
For the latest fixes and updates, go to the Support & downloads website, and search by entering your
system type and controller type.
Verifying the controller software
Verify the minimum software support that is required for your specific controller.
Support for the controller is contained in the Licensed Internal Code of IBM i.
SAS RAID controllers for IBM i
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