pythorlh's Journal: Ask the Circle: RAID help

I've been asked to help out my sister's boss working on their store server. This is a little mom and pop place, but they try to handle their IT intelligently. Their last computer guru moved out of town, so this may lead to some extra cash for me on a semi-regular basis. I'm looking to do a good job.
          There are several things he's looking for, but the main request right now is to upgrade the hard drives. They have a Dell Poweredge server, with two 40 GB IDE drives in a RAID 0 configuration. They're running out of space, and they've bought two 80 GB drives to upgrade with.
          I haven't worked with RAID before. I understand RAID 0 (Oops. I meant RAID 1) is simple mirroring, and I see from their computer's specs that they have a hardware RAID controller. My initial thought was to open the case, pull one of the existing drives (just as if it had gone bad) and place the new drive in the old drive's place. After a rebuild, everything should be fine. Then, same process with the remaining old drive, and a new rebuild. At the end of this process, I expect to have everything working as before, but probably still at the 40 GB capacity. From reading some Dell docs online, I think I can then go in and expand the logical drives to take the full capacity.
          First question, does this sound like it will work? Am I missing something major?
          Second question: There is some reference to adding a hot swappable backup to the RAID 0 configuration. The one concern I have with the steps outlined above is that during the rebuild we don't have a full backup available. Of course, if the rebuild fails, and we haven't made any changes to the data, then we can just pop the old drive back in (I think). Still, if there's a way to alleviate the risk, I'd like to take it. What I'm thinking is putting in a new drive on a third channel, configured as the hot swap. Let it rebuild, then shut down and pull one of the old drives. Put the other new drive in, set as the new hot swap, and wait for the rebuild again. Finally, pull the last old drive, and set the two new drives up with no hot swap. Is this better or worse than my first thought? If better, am I missing anything on this end? I assume that I'd still have to expand the drives after the process to take advantage of the larger space.
          Third question: Am I just crazy, and there's a much simpler solution I've overlooked?

        Any help appreciated

Don't trust RAID!

[Philip K Dickhead]

If you pull one of the drives, make sure it can be read when attached to a regular controller, and keep it aside as a backup in the case of a SNAFU. If it can't be read? Get a backup onto a cheap USB drive before changing any configurations.

I stress - get some form of real, external backup.

You should, in theory, be able to replace/rebuild if you follow the steps just right. Problem: you will have a volume on th enew disk drive, that is partitioned to the old size. You should see if you are able to exte

Re:

[pythorlh]

Yes, that was the problem I expected. Looking at the Dell docs, it seems fairly simple to extend the volume once the rebuild(s) complete.

Thanks for the input.

RAID levels and such

[damn_registrars]

RAID 0 is not mirrored. RAID 0 generally has no redundancy whatsoever, it generally just involves two drives acting as one drive, with the capacity of the two together.

Anyone who runs RAID 0 without some sort of backup system is asking for trouble, as RAID 0 has, well, zero fault tolerance. One failed drive in a RAID 0 and you can generally kiss your data goodbye.

If you want simple mirroring, you want RAID 1. In a RAID 1 array, two drives act as a single drive with the capacity of just one. This gen

Re:

[pythorlh]

Sorry about that, I meant RAID 1. The store already has a RAID 1 running on two 40 GB drives. What I need to do is find the safest and easiest way to expand that to two 80GB drives.

Thanks for the information.

Mostly okay, but...

[peacefinder]

I'm not altogether sure that a Dell RAID controller will allow you to expand the size of the RAID volume after you've put in the new drives. I would recommend a call to support to go over the proposed procedure and have them validate it.

Aside from that, though, it's a reasonable plan.

If I were doing this, I would consider instead:
1) Obtain three new drives
2) Back up to a separate device
3) Add a new drive to slot 3, configure as a non-RAID volume
4) Restore the backup to the new drive
5) Boot the restored imag

Re:

[insanecarbonbasedlif]

This is basically the procedure I would use, but in an abbreviated form:

1) Obtain an external drive (or a drive to connect internally, but not part of the array), and mirror the existing array to that drive.
2) Pull and set aside the existing array drives.
3) Set up the new drives in the array
4) mirror the external drive to the new array.

If this fails in the end, you can simply insert the two old drives and not have missed anything. I've yet to see an array that can't be mirrored (as source or destination) wi

Re:

[peacefinder]

I am guessing that this is a "hardware" RAID - a Dell PERC controller - and can only use drives SCSI attached to that particular controller. In such a case, mirroring to an external drive may not be possible. (Hopefully it is, because your way is certainly simpler.) Again, I'd recommend checking with Dell support to pre-validate the procedure.

Just chiming in

[jawtheshark]

To say that I read it, but all answers have been covered by now ;-)

My two cents

[Sylver Dragon]

I tried something similar a while back on an Appro 1124Hi, and had all kinds of problems. The RAID controller (PERC also, I think) didn't want to expand out to use all of the available space. That said, I would look to do a backup and restore onto a new array.

1. Backup all critical data to an external drive
2. Run defrag
3. Run checkdisk
4. Use Ghost or the like to image the partition
5. Remove the old array drives
   • Side note here, the controller may let you get away with not deleting the array and you have a fallback opti