Raid5 Online Spare

[Brian Stienmeyer]

I have a server that currently has the following setup:

Parallel SCSI Array B
- Logical Drive 3(138919 MB, RAID5)
- Unused Space, 92615 MB

The raid5 is 3 72GB disks, and the unused space is another 72GB disk. I want to make the unused space into an online spare for that array without deleting the array (I have data on the raid5 that needs to stay there). How do I do this in the ACU?

[TTr]

If I understand you correctly, you have a 3-disk raid5 group and you want to take out one of the 3 disks and make it a hot spare.
> ...and the unused space is another 72GB disk
The used AND unused space is on ALL 3 disks.
To take one disk out of a 3-disk raid5 group, means that you will end up with a raid1 group (mirrored pair). Since the unused space is 92GB, the used space is about 50GB and will fit into a 72GB mirrored pair.
You can use the "raid level migration" feature of your raid controller if it is available. You did not mention what kind of controller you have. This feature converts live from one raid level to another. Look in the ACU for this feature.

[Brian Stienmeyer]

No, there are 4 72GB disks. At one point, the raid5 was 3 72GB disk with a hot spare. The hot spare was then taken off and made into a 2nd logical drive. That logical drive was then deleted creating the unused space. I want to get it back to the raid5 3 disk 72GB configuration with the online spare. Here is the array configuration from the ACU:

Controller Smart Array 6i Controller
Bus Interface 64-Bit PCI
Controller Location Embedded

Array B
Array Type Parallel SCSI
Number of Logical Drives 1

Physical Drives Attached to Port 1 SCSI ID 4, 72.8 GB (Parallel SCSI)
SCSI ID 5, 72.8 GB (Parallel SCSI)

Physical Drives Attached to Port 2 SCSI ID 0, 72.8 GB (Parallel SCSI)
SCSI ID 1, 72.8 GB (Parallel SCSI)

Online Spare Drive(s) None
Unused Space on this Array 92615 MB

[TTr · Accepted solution]

> The hot spare was then taken off and made into a 2nd logical drive.
As part on the same array group? And now the RAID5 array has all 4 drives in it? In this case, NO you can not take drives out of the array. You have to offload your data, recreate the array and restore the data.

In general you can add drives to an array group (Online Capacity Expansion feature) but you can not take drives out, even if there is enough empty space.

[Brian Stienmeyer]

Thanks for the confirmation, I kinda figured that would be the case.