IBM SAS RAID 5, Manual

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Chapter 4. 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 SAS RAID disk arrays.
v
Device parity protection
The topic describes the use of device parity protection on IBM i.
v
Managing disk arrays
Refer to this topic to see the interface for performing various tasks with disk arrays.
v
Creating a disk array
Use this procedure to start device parity protection.
v
Using hot spare disks
Hot spare disks are used to automatically replace a disk that has failed in a RAID environment.
v Disk unit management
This procedure allows viewing disk status and disk unit details.
Viewing IBM SAS disk information
This procedure enables you to view SAS disk information, status, and details.
To view the SAS disk information and status, see the following:
v
IBM i Service Functions
v
IBM i Dedicated Service Tools (DST) options
Note: The disk unit information options can also be accessed through System Service Tools. The
system does not need to be in dedicated service mode to display disk information. Some disk
configuration functions do require dedicated service mode.
v Work with disk units
v
Display disk configuration
Note: This display shows disk unit details such as type, model, serial number, operating status,
capacity, and protection status.
Considerations for solid-state drives
Use this information to understand the importance of controller functions when you use solid-state drives
(SSD).
Hard-disk drives (HDD) use a spinning magnetic platter to store nonvolatile data in magnetic fields.
SSDs are a storage device using nonvolatile solid-state memory, typically flash memory, to emulate
HDDs. HDDs have an inherent latency and access time caused by mechanical delays in the spinning of
the platter and movement of the read/write head. SSDs greatly reduce the latency and time to access the
stored data. The nature of solid-state memory is such that read operations can be performed faster than
write operations and write cycles are limited. Using techniques, such as wear leveling and
overprovisioning, enterprise class SSDs are designed to withstand many years of continuous use.
© Copyright IBM Corp. 2009
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