Accusys ExaRAID GUI - Manual (Page 281)

Appendix
B-12
B.11 Convenient Task Management
The RAID controllers are equipped with extensive utilities to support the
system administrator to conduct maintenance tasks, which may be to fortify
the RAID protection by disk scrubbing, to reconfigure RAID attributes by
migrating RAID level or stripe size, or to expand LUN capacity. There are also
other tasks like disk rebuilding or disk cloning that are started by the firmware
automatically. These tasks are done in the background and possess more or
less performance impact to applications accessing the storage system. To
avoid the unwanted downgrade of service levels, the background tasks are
required to be manageable and the administrator needs to have the
flexibility to control the tasks.
• Schedulable task execution
The administrator can schedule the background tasks with appropriate
parameters to be started at a specific point of time, which may be off-peak
hours to avoid degrading the performance of the system. Without this
function, the administrator might be forced to run the task during business
hours, or they have to wait till the end of business hours so as to execute the
tasks manually.
• Periodical task execution
Periodical schedule can be set for the maintenance tasks with appropriate
parameters. This frees the administrator from keeping records of when the
tasks have been done and when to run the tasks again.
• Task execution logging and notification
Logs of task execution are recorded in the non-volatile memory on the
controller, so that the administrator can easily track the execution history of
the tasks. The firmware also sends out notifications to inform the
administrator about the current status of the tasks; As a result, the
administrator can easily monitor the progress, just like they are with the
storage systems.
• Task progress monitoring and auto-resume
The firmware regularly provides the progress report of task execution as well
as estimates when the tasks will be completed. This helps the administrator
to better plan the corresponding actions and manage the expectation of
end users in the organization. The progress is recorded on the hard disks,
and if the storage system is restarted, either normally or abnormally, the
tasks will be automatically resumed at the point when the storage system is
powered off.
• Disk-rebuild priority over maintenance tasks
There are chances that a disk might fail during the execution of
maintenance tasks. To minimize the period of RAID degradation, the
maintenance task will be aborted or paused, and disk rebuilding will be
executed immediately. This reduces the risk of data loss and avoids