Common controller and disk array management tasks
You can perform various tasks to manage SAS RAID disk arrays.
Use the information in this section to manage your RAID disk arrays.
- Using the Disk Array Manager
The Disk Array Manager is the interface for performing various tasks with disk arrays. - Preparing disks for use in SAS disk arrays
Use this information to prepare disks for use in an array. - Creating a disk array
A disk array is created using a set of Active Array Candidate pdisks. - Migrating an existing disk array to a new RAID level
The SAS RAID controller supports migrating an existing RAID 0 or 10 disk array to RAID 10 or 0, respectively. This allows you to dynamically change the level of protection of a disk array while preserving its existing data. - Viewing the disk array configuration
Use this procedure to view SAS disk array configurations on your server. - Deleting a disk array
To preserve the data on the disk array, you must first back up all files in the logical volumes and file systems on the disk array before removing the disk array from its volume group. - Adding disks to an existing disk array
Some controllers support adding disks to existing RAID level 5 or 6 disk arrays, which allows you to dynamically increase the capacity of a disk array while preserving its existing data. - Using hot spare disks
Hot spare disks are used to automatically replace a disk that has failed in a redundant RAID environment. For disk arrays with Easy Tier® function, it is important to note that a hot spare disk will only replace a disk in the tier that has the similar performance characteristics as the hot spare. Therefore, you need different hot spare disks available to fully cover all tiers in a tiered RAID level. For example, an SSD hot spare and a HDD hot spare. - Viewing IBM SAS disk array settings
This procedure enables you to view SAS disk array attributes and settings. - Viewing IBM SAS pdisk settings
This procedure enables you to view SAS pdisk attributes and settings. - Viewing pdisk vital product data
You can display a pdisk's vital product data (VPD). - Viewing controller SAS addresses
View SAS addresses (worldwide IDs) associated with each of the controllers ports. - Controller SAS address attributes
Interpret the results of viewing the controller SAS addresses. - System software allocations for SAS controllers
AIX has system software resources allocated for the maximum number of attached devices, the maximum number of command elements, and the total size of all outstanding data transfers by active commands. The following procedures describe how to view and change those settings. - Drive queue depth
For performance reasons, you might want to change the disk command queue depth. The disk queue depth limits the maximum number of commands that AIX software can issue concurrently to that disk at any time. Increasing a disk queue depth might improve disk performance by increasing disk throughput (or I/O) but might also increase latency (response delay). Decreasing a disk queue depth might improve disk response time but decrease overall throughput. The queue depth is viewed and changed on each individual disk. When changing the disk queue depth, the command elements and data transfer window on the parent adapter might also need to be changed. - Multiple I/O channels
The PCI Express 3.0 (PCIe3) SAS adapter family supports multiple I/O channels. This support enables the adapter device driver to process multiple interrupts in different threads simultaneously, thereby potentially improving performance. Increasing the number of channels that are used by an adapter might improve disk performance by increasing disk throughput (or I/O), but might also increase kernel-thread processing speed. The ideal number of I/O channels must not be more than the number of RAID arrays that are optimized on an adapter or lesser than the number of physical processors that are assigned to the system partition. The number of I/O channels can be viewed and changed on each individual RAID adapter. - AIX command-line interface
Many tasks used to manage the SAS RAID controller can be performed by using the AIX command line instead of using the SAS Disk Array Manager. - Considerations for solid-state drives (SSDs)
It is important to understand controller functions when using solid-state drives (SSDs).
Parent topic: SAS RAID controllers for AIX
Last updated: Wed, May 24, 2017