Increasing RAID size

[heyjim]

I'm fairly sure I know the answer but better ask to be sure!

On one of our servers, we have 4 x 300GB disks in RAID 10 to give us 600GB usable space.

Can we add 2 further 600GB drives to increase the size or do the disks all need to be the same?

Thanks

 

[PliotronX]

You can use the 600 giggers but they will only have 300GB of usable space IIRC.

 

[imagoon]

Depends on the drive controller and the OS to a lesser degree. Dell PERC or HP Smart Array can reconfigure to add the additional disks and then you extend the OS partitions afterwards.

 

[_Rick_]

How/If this works probably depends mostly on the specific implementation you are running.

Given that RAID 10 is a stripe of mirrors, the mirror step is easy, as you just mirror both 600GB disks. If you use balanced striping, you can use 300GB of each disk.
I'm not sure unbalanced striping makes much sense. What you could try is to JBOD the two 300GB mirrors, and then stripe across the 600GB JBOD and 600GB disk to get a quasi RAID 10.

If size is critical, the latter option would double your space at roughly constant performance (and likely a head ache setting it up and documenting it). If size isn't critical, the former option gives you 50% more performance and space.

 

[heyjim]

You can use the 600 giggers but they will only have 300GB of usable space IIRC.

Thought so - probably not too bad as the 300GB drives may well be replaced in the future to 600GB.

Depends on the drive controller and the OS to a lesser degree. Dell PERC or HP Smart Array can reconfigure to add the additional disks and then you extend the OS partitions afterwards.

The controller is a Dell PERC 6.

Yep, I've increased/decreased the OS drives before and worked fine 🙂

I'm not sure unbalanced striping makes much sense. What you could try is to JBOD the two 300GB mirrors, and then stripe across the 600GB JBOD and 600GB disk to get a quasi RAID 10.

That's what a I was kind of hoping I would be able to do - just not sure if it will be possible without having a nosey round in the RAID settings.

Unfortunately space is fairly critical for this 🙁

 

[imagoon]

PERC 6 you would use open manage and tell it to reconfigure, then add the disks to the array. Once they are added, you would extend the volume in the raid card, then rescan and extend it in the OS. You would lose the extra 300GB of the 2 new disks.