Question about RAID 1+0

[mcseguy9]

In our server room we have a HP DL360 G5 that has some drive mirroring going on. 4 of the drives are utilizing RAID 1+0 where two drives are seen as a single drive and than mirrored to the other two drives, which are also seen as a single drive. I need to increase the capacity of those drives and I've found that I can replace each one, one at a time, with larger capacity drives and this will work. I don't have to break any mirrors, make any configuration changes, etc. However, what I don't know is how long to wait for each drive to complete the mirroring process.

In other words, say drives 1-2 are one set and 3-4 are another set. Now let's say I replace drive no. 4 with a larger drive. It will take time for that new larger drive to go through the process of being completely merged with drive 3. Does anyone know how I'll know when that's done so I can then continue on and replace drive 3 with a larger capacity drive, followed by each of the other drives after that?

[Tuttle]

The HP storage software should tell you that. You might be able to figure it out from the LEDs on the front, but I would *not* rely on that.

Also note that it's a fairly high-risk operation -- if one of the other drives dies during the process, you've probably lost everything.

I'd also be surprised if what you propose actually does what you want -- online RAID reconfiguration is fairly complicated, so I'd expect there to be more to it afterwards.

[SpywareDr]

RAID 1(+0): breaking mirrors and rebuilding drives
How to, 3rd edition
http://h20000.www2.hp.com/bc/docs/su.../c00378986.pdf

Introduction
When using a configuration with RAID 1(+0) volumes attached to Smart Array controllers, it may be necessary to break a mirror and rebuild the drives. For example:
...
When increased capacity is required, an administrator can replace half of the drives in a RAID 1 or RAID 1+0 array with larger capacity drives and rebuild the new drives. Afterwards, the administrator can replace the other half of the drives and allow them to rebuild in the other direction. Once all drives in the array are of larger capacity, the administrator can use the Array Configuration Utility (ACU) to increase the logical drive size or to configure additional volumes.
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For RAID 1+0 configurations, the first n/2 drives are always mirrored to the second n/2 drives.
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The drive-online LED will blink during the rebuild process. When it stops blinking and turns solid green, the rebuild is complete. On a 36-GB Ultra 320 drive, depending on the number of IOPS the server is submitting to the controller, it takes about 6 minutes to rebuild a mirrored array when the controller rebuild priority is set to high.

In your case, it sounds like drives 1&2 are being mirrored to 3&4. If so, it sounds like the basic steps would be: power down properly, remove 3&4 (and label them), power up, let the system know that you know drives 3&4 are missing, power down again, attach a new 3&4 set of drives, power back up and wait for the mirror to rebuild. Now follow the same procedure but with set 1&2.

Note: Recommend reading the "HP DL360 G5" documentation for the exact procedure.

[mcseguy9]

Thanks for the help, guys. I appreciate it. I'll let you know how it goes.