3

We have an HP ProLiant ML350 G5 server with an 8-bay RAID 5 array configured on a Smart Array E200i controller. The system volume and data are on the same logical drive. The drives are 72GB each and we are running out of space. All the bays are used up. We have considered external storage expansion and using an archive drive to move the data temporarily while we upgrade the array, but given it's a system drive, that could get tricky.

We came up with this plan and would like some validation this will work:

  1. Verify full data backup is completed. Remove 72gb drives from bays 1-4, breaking the array.
  2. Put in new drives into bays 1-4 (600gb drives). We are fully aware that adding these drives to the existing array will not utilize all the space, yet.
  3. Let the array rebuild.
  4. Remove drives from bays 5-8, breaking the array again.
  5. Now, all the data is also on the first 4 600GB drives, so we can expand the array to the full size and remove the last 4 drives from the logical drive.

The part I am mainly unsure of is how to remove the last 4 drives from the array logically and whether or not this will work at all. Thanks for any insight.

UPDATE: Since I can't mark a comment as the answer, I'll update the post. In the end, we had no other solution than to backup all the data, replace the drives, recreate the arrays and restore. This is relatively nerve racking when you don't do it often, so we put a test plan together and used Macrium Server to backup to a USB 3 drive and restored from that once the new drives were in place. Before replacing the drives we made sure we could access all the backups and had a plan B. It took a while, but it did work and now they have plenty of space available. Thanks.

John Virgolino
  • 687
  • 8
  • 17
  • 5
    Sorry, maybe I'm misunderstanding something here, but if this is an 8 disk RAID 5, steps 2 and 4 will completely destroy your data. There will be no rebuild in this scenario. – MDMarra Oct 07 '13 at 16:18
  • @MDMarra If we replaced one drive at a time, waited for the rebuild, wouldn't that maintain data consistency then? Is there a better way to do this? – John Virgolino Oct 07 '13 at 16:25
  • 1
    One at a time, yes. That's not what your post says, though. – MDMarra Oct 07 '13 at 16:27
  • 2
    Why not make a full backup (and test it!). Pull all 8 drives and replace them. Recreate a new array and restore from your backup? – Hennes Oct 07 '13 at 16:27
  • @MDMarra I appreciate your answer. I realize my post did not say that. We have generally not run into issues with arrays failing, so doing a forced fail for this purpose is a bit scary and we are trying to make sure we cover all the details. – John Virgolino Oct 07 '13 at 16:31
  • @Hennes Thanks - that approach is a bit too risky in this case. I prefer the incremental approach, not to mention that we have to keep the server running throughout the process as much as possible. A full restore would require too much down time. – John Virgolino Oct 07 '13 at 16:33
  • Keeping the server running is a good reason. Keep in mind though that RAID-5 only has one single spare disk. So if one fails during the rebuild you have a problem. Which makes step 1) A new BACKUP and step 2) Test the backup. Then you can start with disk by disk replacement. One disk at the time. And make sure that the rebuild is completed before you swap the next one. This might take longer then you expected and disk performance might be low during the rebuild. – Hennes Oct 07 '13 at 16:36
  • Useful to read: [http://serverfault.com/questions/339128/what-are-the-different-widely-used-raid-levels-and-when-should-i-consider-them](http://serverfault.com/questions/339128/what-are-the-different-widely-used-raid-levels-and-when-should-i-consider-them). It explains the difference between RAID-5 and RAID-10. Pulling four drives at once in a RAID-10 could work. – Hennes Oct 07 '13 at 16:42
  • The one drive at a time makes sense, but what happens when I reach the 5th - 8th drives which won't have replacements. I am trying to leave room for future expansion. I have never had to remove a drive from an HP configuration (it has worked on other manufacturers), will it allow me to do that? – John Virgolino Oct 07 '13 at 16:43
  • let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/10939/discussion-between-hennes-and-john-virgolino) – Hennes Oct 07 '13 at 16:58

1 Answers1

2

Why not just replace all eight disks with 300GB drives (cheaper and make more sense for your server)? You can remove them one-by-one and handle the array transformation online.

There's no concept of "breaking the array" in a parity RAID setup. That would potentially work in a RAID 1+0 configuration, but that's not the case here.

ewwhite
  • 194,921
  • 91
  • 434
  • 799