Managing
Raid GroupsThis help page provides information to guide you through the procedure to expand a RAID group. It contains the following topics:
You can expand the capacity of the RAID group for AMS systems without interrupting host I/O by adding a drive to the specified RAID group. Data is reallocated as a background process and may require some time to complete.
RAID groups may be expanded with the following restrictions:
Only one RAID group can be expanded per command from Navigator 2, but you can execute the command multiple times, which allows you to expand more than one RAID group per Navigator 2 session.
The RAID group expansion process operates on a maximum of two RAID groups at a time. This means that if you issued the expansion command to additional RAID groups, those commands are queued and the expansion will be executed and other RAID groups have completed their expansion process
This section provides important requirements and conditions required to expand a selected RAID group properly.
1. You cannot expand a RAID group when the LU whose status of the forced parity correction is any of the following status messages observed in the RAID group of the expansion target:
”Correcting”
”Waiting”
”Waiting Drive Reconstruction”
”Unexecuted”, ”Unexecuted 1” or ”Unexecuted 2”
If any of the above messages are displayed, you need to execute a forced parity correction for this LU, change the LU status to ”Correction Completed”, and then execute the RAID group expansion.
2. You cannot expand a RAID group if an LU is being formatted and belongs to the RAID group expansion target. Wait until the formatting has completed and then execute the expansion command from Navigator 2.
3. You cannot expand a RAID group if the following LU types are in the RAID group of the expansion target:
LUs set for a pair other than PSUS of ShadowImage in-system replication
LUs set for a pair other than PAIR of Copy-on-write SnapShot
LUs set for a pair other than PSUS of TrueCopy remote replication
LUs set for a pair other than PSUS of TrueCopy Extended Distance
LUs or reserve LU during Modular Volume Migration
LUs in which Cache Residency Manager is set
For any of the above conditions, change the LU status and then expand the RAID group.
4. You cannot expand a RAID group after setting or changing Cache Partition Manager configuration. The array must be rebooted. Expand the RAID group after rebooting the array.
5. You cannot expand the RAID group in which the Power Saving function is set. Change the status of the Power Saving feature to "Normal (spin-up)” and then expand the RAID group.
6. You cannot expand the RAID group when the dynamic sparing/correction copy/copy back is operating. Expand the RAID group after the drive has been restored.
7. You cannot expand the RAID group while installing the firmware. Expand the RAID group after completing the firmware installation.
Host access performance deteriorates during the RAID group expansion. Specifically, the LU in the RAID group which is expanding mostly affected. Execute the RAID group expansion at a time when host I/O is at a minium.
For RAID group expansion, you can specify whether to give priority to the host I/O or the RAID group expansion itself.
Perform backups of all data, including data stored in cache memory, before executing the expansion. Data loss may occur due to a power or some other type of system failure, and the LU associated with the expansion may become unformatted.
The RAID group expansion expands the number of data disks of the RAID group. You cannot change the RAID level, for example from (4D+1P) to (4D+2P). You may expand the RAID group from RAID 1 to RAID 1+ 0. You cannot expand a RAID group that has a RAID level 0.
Only RAID groups that have one parity group may be expanded
You can use the added capacity immediately after the expansion process has completed
The total number of hard disk drives (HDD) that you can add is 8 per RAID group.
The drive to be added must be of the same drive type (SAS or SATA) as the RAID group of the expansion target. Moreover, the capacity more than or equal to the minimum capacity drive in the RAID group of the expansion target is required.
We strongly recommend that the drive added be of the same capacity and rotational speed as the RAID group of the expansion target to maximize performance.
When expanding the RAID group of RAID 1 or RAID 1+0, add drives in multiples of 2.
To expand RAID group:
From the RAID Groups window, select the RAID group you want to expand and click Expand RG.
Select a drive to add from the Assignable Drives table.
If you want to see the resulting capacity of expanded RAID group, click Refresh Capacity of Extended RAID Group, the expanded capacity is displayed.
Select the desired priority you want when the RAID group is expanding, either Host Access or RAID Group Expansion.
Host Access sets priority for Host I/O operations. This means the expansion process will require more time to complete.
RAID Group Expansion sets priority for the expansion operation. This means the expansion process will require less time to complete.
Click OK and the confirm dialog is displayed. Check the box and click Confirm or click Cancel to exit without expanding RAID group.
Click Close to close and confirm the RAID Groups window.
See Also (back to top)
The following topics within this help system provide information that may be helpful in understanding the information on this page, and/or may provide additional information that is related, but not required to understand this topic.
Changing
Capacity on Existing Logical Units