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Raid 5 to Raid 0

Tom Holdren
Occasional Visitor

Raid 5 to Raid 0

I am a product consultant for a small company that also serves as a part-time network administrator.(9 person office, no full-time network admin) Anyway, my boss is convinced that we need more space on our server yet he does not want to purchase another hard drive. We have a server with 3 9gb drived that are using raid 5 so our real total space is about 18gb. He is insistent that we unraid them to get an extra 9 gb of space. I told him of the consequences(one goes, they all go). He is still willing to take that chance. Any suggestions? My plan was
1) get a good backup-just in case
2) change the raid settings from 5 to 0
3) reboot

I am sure it is not that simple but I am not sure. In theory will I lose any data or will it sort itself out. What types of things should I be prepared for. Will I need to run a restore? Or only restore if things go wrong?

Tom Holdren
Occasional Visitor

Re: Raid 5 to Raid 0

By the way this server is running windows nt 4.0
Gert Luyten
Respected Contributor

Re: Raid 5 to Raid 0

When posting to this forum, always give as much details as possible (server model, RAID type (hardware or software), RAID controller model, amount of data on the R5 drive, etc..).
In this way, we can answer your question.
A Proliant a day keeps the competition away!
Leif Halvarsson_2
Honored Contributor

Re: Raid 5 to Raid 0

Does your Raid controller support changing Raid level without loosing the data. Most entry level Raid controllers does not.
Your plan seems OK but you perhaps have to restore the data again after reconfiguring the Raid controller.
Seth Parker
Trusted Contributor

Re: Raid 5 to Raid 0

Leif has an excellent point. If your boss isn't willing to spend the money to buy a $300 drive, it seems unlikely that the card would be smart enough to change the RAID level on the fly. I did a quick search and it looks like the 5300 controllers can, but not the LC2 controllers.

One thing I can say for sure it that if you do this, it's not going to be fun to be you! We had a drive go out the other day on one of our servers. However, since it was mirrored, no one even noticed. Same thing for RAID 5. We've had drives go bad in the past and no one noticed (until we put the new drive in and it started the rebuild).

Maybe you could offer to split the cost of the drive with the company? Hehe, it might be worth it to you for peace of mind!

Ok, now for your actual question. If you've got something like the 5300, your procedure outlined above seems right according to the user's guide (I'm assuming all along that you're using Compaq gear), but without the reboot. You do your backup, run ACU, set the new RAID level under Migrate Stipe/RAID Level, then let it migrage the data to the new level. The manual says it takes about 15min/GB.

Good luck!

Re: Raid 5 to Raid 0

Are you using Hardware Level or Software Level Raid at present. It is potentially possible that you dont have a RAID card in the machine at all and you are using disk striping within NT ?

Some details of your hardware/software configuration will help the group post a useful suggestion on your next step
David Holbrook
Regular Advisor

Re: Raid 5 to Raid 0

Even more important, which you did not say, is you OS on a partition under the raid5? If so, you have a massive amount of work ahead of you to totally rebuild the system.

If the raid is just for data, you must totally back up the data (and make sure the restor will work!), as it probably will not fit on a single drive anymore like it does now on the raid5 (max drive size will be only 9GB in the new configureation).

In addition, if any applications are installed on the Raid5, then they will most likely NOT work in the new configuration, because the drive letter will be wrong, and the application will need to be re-installed from scratch too (hope you can find the original install disks and license information!). Because you do not know which drive the data is stored on, you will lose everything once you disolve the array (data is striped across all three drives in the array). Your time will cost him more than the drive does too.

You have my sympathy, and good luck. David