Reverse an AX150 expansion

You can't. You'll have to back up your data, plan for complete downtime and destroy your setup. You can grow, but never shrink. This goes for virtual disk sizes as well as diskpools (number of disks in a diskpool).

After you back up your data you delete all virtual disks and destroy the diskpool.

After that you can create a new diskpool or diskpools.

In any raid set (doesn't matter what kind of raid controller) a diskpool (or the equivalent for another raid controller (i.e. it may have another name)), the smallest disk is what sets the max size you can use per disk, so mixing drive sizes means you're wasting space on the larger drives.

I see said the blind man....

 

That being said, there isn't anyway this system is going down for a rebuild, so I have another question or two.

 

Can I remove the two 750GB drives (one at a time) and replace them with 250GB drives instead?  I assume if I pull one it will think of it as a failure anyways and it will rebuild the new 250GB drive.

 

Although I have not allocated any of the new raw space from the expansion, I assume just pulling them out will really tick it off.

 

 

You may want to consider purchasing one more 250GB drive and one more 750GB drive. 

You could use your current hot spare as one of the replacement disks along with a additional 250GB drive.

The additional 750GB drive I'm recommending would be for the new hot spare.  The hot spare needs to be as large as the largest drive in the system.

 

I would recommend:

1. Perform a complete backup of your data
2. Verify there are no alerts on the needs attention page, or the state of the array is "normal" 
3. Disable the hot spare
4. Remove one of the 750GB drives (unseat and let spin down prior to fully removing the drive)
5. Replace with a 250GB drive, monitor and wait for all the virtual disks to rebuild, do not continue until they are finished and there are no alerts (with the exception of no hot spare)
6. Repeat for the other 750GB drive.
7. Configure a hot spare with a 750GB drive.
8. Add the 750 drives and create a new Disk Pool with them.