A master volume on a P2000 G3 array is a volume that has the ability to have snapshots. If the volume is created via the GUI as “snappable” then the volume is automatically created as a master volume. Likewise if you add snapshots to the volume sometime after the volume has been created it is automatically converted into a master volume.
The issue around master volumes is that they can not be expanded. In the GUI that option is simply grayed out. To expand the master volume you will need to login to the P2000 via SSH and use the CLI to:
- Remove any snapshots
- Convert the master volume into a standard volume
- Expand the volume
- Expand the snap pool (optional)
- Convert the volume back into a master volume
The steps to accomplish this is covered below for an example volume called Web with a snap pool called spWeb.
# show volumes Vdisk Name Size Serial Number WR Policy Cache Opt Read Ahead Size Type Class Qualifier Volume Description --------------------------------------------------------------------------------------------------------------------------------------- vd01 Web 99.9GB 00c0ff10a5ce00000102db4d01000000 write-back standard Default master volumePTSNAP N/A vd01 spWeb 19.9GB 00c0ff10a5ce0000dbe3de4d01000000 write-back standard Default snap pool PTSNAP N/A ---------------------------------------------------------------------------------------------------------------------------------- Success: Command completed successfully.
First we should check if there are any snapshots
# show snapshots Vdisk Serial Number Name Creation Date/Time Status Status-Reason Source Volume Snap-pool Name Snap Data Unique Data Shared Data Priority User Priority Type ---------------------------------------------------------------------------------------------------------------------------------- vd01 00c0ff10a5ce0000bce2de4d01000000 Web_s001 2011-05-26 23:31:08 Available N/A Web spWeb 393.2KB 393.2KB 0B 0x6000 0x0000 Standard snapshot ---------------------------------------------------------------------------------------------------------------------------------- Success: Command completed successfully.
There is one snapshot called Web_s001 which we should delete using the following command. Of course once the snapshot is deleted any unique data contained within the snapshot will be lost.
# delete snapshot Web_s001 cleanup Info: Snapshot Web_s001 was deleted. (Web_s001) Success: Command completed successfully.
The cleanup argument will convert the master volume into a standard volume if the last snapshot for that volume is deleted. We can now see that the Web volume is a standard volume.
# show volumes Vdisk Name Size Serial Number WR Policy Cache Opt Read Ahead Size Type Class Qualifier Volume Description --------------------------------------------------------------------------------------------------------------------------------------- vd01 Web 99.9GB 00c0ff10a5ce00000102db4d01000000 write-back standard Default standard standard N/A vd01 spWeb 19.9GB 00c0ff10a5ce0000dbe3de4d01000000 write-back standard Default snap pool PTSNAP N/A
If you have multiple snapshots you can just run this command for each snapshot or you can use the command below to delete all snapshots for a volume.
# delete all-snapshots volume Web Info: This may take a few minutes if the system is under heavy load... Success: Command completed successfully. (Web) - All snapshots were deleted.
This command does not have a cleanup argument so you will need to manually convert the master volume into a standard volume like so.
# convert master-to-std Web Success: Command completed successfully. (Web) - The conversion of a master volume to a standard volume completed.
Now we are ready to expand the Web volume. In this example we add another 100GBs to the volume.
# expand volume size 100GB Web Success: Command completed successfully. - Expansion of volume Web was started. # show volumes Vdisk Name Size Serial Number WR Policy Cache Opt Read Ahead Size Type Class Qualifier Volume Description --------------------------------------------------------------------------------------------------------------------------------------- vd01 Web 199.9GB 00c0ff10a5ce00000102db4d01000000 write-back standard Default standard standard N/A vd01 spWeb 19.9GB 00c0ff10a5ce0000dbe3de4d01000000 write-back standard Default snap pool PTSNAP N/A --------------------------------------------------------------------------------------------------------------------------------------- Success: Command completed successfully.
We can now see that the Web volume is 199.9GB instead of 99.9GB.
Expanding the volume does not expand the snap pool for the volume. Depending on your needs you may want to increase the snap pool to match the same ratio that existed before. In our case the snap pool was 20% of the Web volume’s original size so we will increase the snap pool so it remains 20% (i.e. we are going to increase it to around 40GBs).
# expand snap-pool size 20GB spWeb Success: Command completed successfully. (spWeb) - Expansion of volume spWeb was started. # show volumes Vdisk Name Size Serial Number WR Policy Cache Opt Read Ahead Size Type Class Qualifier Volume Description --------------------------------------------------------------------------------------------------------------------------------------- vd01 Web 199.9GB 00c0ff10a5ce00000102db4d01000000 write-back standard Default standard standard N/A vd01 spWeb 39.9GB 00c0ff10a5ce0000dbe3de4d01000000 write-back standard Default snap pool PTSNAP N/A --------------------------------------------------------------------------------------------------------------------------------------- Success: Command completed successfully.
Lastly we need to convert the volume back into a master volume.
# convert std-to-master snap-pool spWeb Web Success: Command completed successfully. (Web) - The conversion of a standard volume to a master volume completed. # show volumes Vdisk Name Size Serial Number WR Policy Cache Opt Read Ahead Size Type Class Qualifier Volume Description --------------------------------------------------------------------------------------------------------------------------------------- vd01 Web 199.9GB 00c0ff10a5ce00000102db4d01000000 write-back standard Default master volumePTSNAP N/A vd01 spWeb 39.9GB 00c0ff10a5ce0000dbe3de4d01000000 write-back standard Default snap pool PTSNAP N/A --------------------------------------------------------------------------------------------------------------------------------------- Success: Command completed successfully.
While it’s not great that you have to blow away all your snapshots to expand a volume, at least it’s not too difficult to accomplish the task.
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