Array expansion and extension

[Larry Shaw]

We have a DL380 running WS2000. The server currently contains four 36 GB drives in a RAID5 array with a hot spare.

We want to extend the system by swapping in 72 gb drives and adding two more 72 GB drives.

Should we add the two 72 GB drives and extend the array and then swap the original 36 GB drives and then create a new array with the un-used space or should we first swap to 72 GB drives with a replacement and rebuild and then add the two drives and extend the arrays?

My though would be to add the two drives and extend the existing array and then swap the existing drives and create the new array from the new space available but would appreciate any guidance on the best approach.

Of course I know there is also the option of backing it up and rebuilding from scratch but would rather not do that if we can do it online.

[sandeep_raman]

Hello Larry,

First let me get it right,

Existing Array A -> Raid 5 -> 3*36Gb + 1*36Gb hotspare

Your requirent -> Array A -> Raid 5 -> 3*72Gb + 1*72Gb hotspare

SRH

[Larry Shaw]

Not quite.

Now 4x36 GB in RAID5 with Hot spare.
Desired 6x72GB in RAID5 with hot spare.

[sandeep_raman]

Backup/Restore is more easier and time saving.

Reasons:

1.diskpart cannot extend system volume and you may have to use 3rd party tools. http://support.microsoft.com/kb/325590/en-us

2.You have to take out 1 disk @ a time and wait until it rebuilds which may be a few days.

SRH

[Larry Shaw]

We normally use dynamic drives and extend them to different disks in Windows. We've found that it takes about two hours per drive to do the rebuild. We've done many of them...but usually do not do an expansion and extension at the same time.

Our question is "Add the drives and extend the current array first or swap and rebuild the drives first and then add the new drives.

[sandeep_raman]

Well, i think the first one you mentioned is more of a software raid where you use a scsi controller and the OS manages the raid.

What i was referring to was a hardware raid implementation which uses a smart array controller.

So if its a hardware raid,then i stick to my earlier response.

"Add the drives and extend the current array first" , how do you plan to take the old 36Gb disks off?

"swap and rebuild the drives first and then add the new drives" , how do you plan to make the additional unused storage part of the array?

SRH

[Larry Shaw]

In either case, I will swap the 36 GB drives to 72 GB drives one at a time and let them rebuild.

In either case, I will expand the array of drives in hardware and add one or more logical drives in the SmartArray and then use Windows 2003 or Windows 2000 drive extension to add that new Array logical drive to the Windows volume.

[sandeep_raman]

It would be interesting to see if you can extend the system volume.

SRH

[Larry Shaw]

This is not the system volume.

The system volume is on a separate logical disk in the array. The volumes to be extended are strictly data volumes.

C: is on one logical disk defined as a basic disk in it's volume. The data drives are all on a second logical disk defined as a dynamic disk. This is the disk which will be extended.

[sandeep_raman]

Hmmm, you never specified this before inspite of me posting the MS doc.

Since its not a sys volume,it'll work.

1.Add the new disks to existing array(Array A/B) one at a time and wait for rebuild to complete.Don't swap 2 disks at a time since Raid 5 fault tolerance is single disk only.

2.Add the additional storage to the existing logical volume(Volume A).

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00687518/c00687518.pdf
Pg 5-7

3.Use diskpart utility to extend the data volume.

http://support.microsoft.com/kb/325590/en-us

SRH