Removing Drives from an Array

[Jeff Mack]

I have a Proliant ML 350 with a Smart Array 641. I initially configured the server with a three 18 GB disk array. It is a single RAID 5 Array that had 1 logical drive with 2 partitions. We quickly out grew that configuration and had to add three additional drives. We added three more 18 GB drives to the existing array and created a second logical drive on the array. This gave us another 54GB of space. I thought we would be in good shape.

Since then, our managment has decided to test a new software package that recommend a minimum of 100 GB of disk space for document managent. I had a few recomendations including a new server or a SAN, but managment wanted to see if there were any other solutions that would enable us to test the new software package for less cost. So, I purchased three 150GB drives thinking I could remove the second logical drive I created in the single RAID 5 Array. Then I was going to remove the three 18GB Drives from from the RAID Array. Then I could add the three new 150GB drives back into the Array and create the second logical drive. And managment would be happy that we were able to test the new software appliaction for very little cost.

So, my delimia: Can I do this with the smart array 641? Can I regain the 3 SCSI ports on the RAID Array without losing everything? Can I remove the drives from the Array?

Thank you in advanced,
Jeff

[Uwe Zessin]

Unfortunately, that won't work. The SmartArray controllers are smart, but not THAT smart...

I have never seen any sign that you can permanently shrink a disk driver array. You would have to upgrade to 6 disk drives, 150GB each, or restart from scratch.

[Jeff Mack]

Can you give me more information on upgrading all the drives in the Array to 150GB drives? Once they are all rebuilt, would there just be extra space on the Array to configure, or will I need to do anything else?

Thanks,
Jeff

[Greg Carlson]

Jeff,

You can delete the last logical drive in the ACU, however you are still stuck with the array and you can't remove three drives from your array configuration. The only way to change your configuration would be to delete your array, recreate it minus the three 18gb hdds and restore from backup. That will free up your three bays for your 146gb hdds for your raid 5.

Ciao,
Greg

[Jeff Mack]

I saw a post explaining that you can replace each of the small drives with larger drives in an array, one at a time (letting it rebuild after each drive is installed). It said once all of the drives were replaced, there would be additional free space that could be configured.

Can anyone confirm or deny this? And if this does work, is it as easy as replacing the drives, or is there other steps?

Jeff

[Uwe Zessin]

I have never done it myself (I don't do much with the SmartArrays), but I have seen several success reports here on ITRC and I think I have read about it in HP's documentation - can't cite a document, though.

The 'trick' is to rip out a smaller disk drive and replace it by a bigger one. Then you have to wait until the normal RAID rebuild has finished. Repeat this with each small disk drive. By the end you should have a disk drive array that automatically has 'won' free space.

Please remember that during an extended time your RAID redundancy is compromized. If any additional disks failes (unless you run with ADG, of course) and your data might have gone.

[Jim_359]

I am responding to the earlier can I just add drives. Actually this is one of the great things on these array controllers. However the limitation is on the array itself. IE if you have ARRAY A with a logical drives, this array will only use the space avaiable based on the smallest drive that makes up that array A. So if you have 5 drives 4 146 and 18, the array will be based on the 18 gig drive and will look at them all as 18 for the raid. So based on this replace one at a time each drive with the same size larger drive. Make sure that your array has finished rebuilding before adding the next drive. Once all the drives have been replaced to the bigger drives, you will now have available unused space to assign to your logical drives. It is somewhat time consuming but does work like a charm. I am assuming you have a raid controller and hot swap type drive array.