topic Re: RAID Array in ProLiant Servers (ML,DL,SL)

RAID Array

Steeve Hébert — Wed, 22 Sep 2004 09:15:58 GMT

Hi,

I set an array on my server. It's a RAID 0 with 2 disks. Last week end, I removed the "slave" disk to test my RAID. The server start and it gives me two choices. F1 - Ignore all drives and continue F2 - Try to boot with fault tolerence. I tried F2, but no boot system was find.

The server is a Proliant 370ml P3-600 mhz.

I insert a snapshot of my RAID config.

Is my Array correctly confugure OR I made a mistake when I tried to boot with only 1 disk ?

Thanks

Re: RAID Array

JohnWRuffo — Wed, 22 Sep 2004 09:23:02 GMT

RAID 0 has NO fault tolerance. When you removed the drive, you broke the array. Failure of ANY drive in a RAID 0 results in loss of all data.

Re: RAID Array

Rick_119 — Wed, 22 Sep 2004 09:25:26 GMT

Raid 0 is disk striping only and not any mirroring, you need to use Raid 1 for what you are trying to do

here is a link to read on raid and Stripping

Striping

http://www.pcmech.com/show/harddrive/296/2

Raid
http://www.pcmech.com/show/harddrive/296/3

Re: RAID Array

Steeve Hébert — Wed, 22 Sep 2004 10:00:00 GMT

Hi guys,

I feel a a a ... I don't know how to explain, but I don't fell good.

You can be sure that I will read your link.

With the Array Configurator ( Windows version ) can I convert the actual Array to a RAID 1 Array ?

Thanks

Re: RAID Array

JohnWRuffo — Wed, 22 Sep 2004 10:24:45 GMT

At this point, you can do anything. The data will need to be recovered from your last backup.

If you have two drives, you can configure a RAID 1. This will give you fault tolerance but at the cost of half the total space.

For example, if you have two 36GB drives (2x36) you will have a total of 36GB of logical drive space. Not 72GB as would be for RAID 0.

Let me know if you need any more help?
G'luck! -john

Re: RAID Array

Steeve Hébert — Wed, 22 Sep 2004 10:35:31 GMT

Hi,

If I understand correctly, I can't came back...

Previously, all the data was on only one drive. I configured the RAID 0 (It take about 3 hours to do).

So, I can't ask to the controler to put back all the data on the same drive ?

Please help... I'm in a nightmare !!!

Re: RAID Array

Rick_119 — Wed, 22 Sep 2004 10:45:38 GMT

Why not put the drive in that you pulled bring the server back up and use the ACU to go to raid 1?

Re: RAID Array

Rick_119 — Wed, 22 Sep 2004 10:47:59 GMT

my previous post is assumng the ACU will let you migrate from 0 to 1

I was able to go from raid 1 to raid 5 with the ACU so that is what my assumption is based upon... the ability to go to a higher level of raid.

Re: RAID Array

Steeve Hébert — Wed, 22 Sep 2004 10:56:16 GMT

Hi,

What is ACU ?

At the moment, the server is up. It working perfectly.

Can I use the Compaq Utility to go back on 1 drive ?

If not, Actually, I have 2 disks (18.2 go) in Raid 0. If I buy a new 18.2 go disk, can I configure the controler to create a mirror of the Raid 0 ?

Thanks

Re: RAID Array

Rick_119 — Wed, 22 Sep 2004 11:12:46 GMT

ACU is the array configuration utility on your server look for in the start>programs section a tab for Compaq/HP utilities (not near the server right now so I can't give exact detail.

use the ACU to configure the server to a raid 1 with the 2 drives you have.

Once again I am not usre if you can go from raid 0 to 1 without loss of data, but follow the directions with the ACU and it will give you a warning if it is not possible.

Here is a link to the latest ACU (Thanks John)

http://h18000.www1.hp.com/support/files/server/us/download/21709.html

Re: RAID Array

Greg Carlson — Wed, 22 Sep 2004 11:25:14 GMT

Steeve,

It is my understanding that you can't go from a two disk raid 0 to a two disk raid 1 configuration as there isn't enough room for the data to be restriped onto a single disk. You may only have had enough data to fill up one hdd, but remember its striped equally across the two hdds. If you are in a 2 disk raid 0, I believe your option is to add another hdd and then convert from raid 0 to raid 5. This will give you the capacity of 2 drives with 3 installed. Your capacity will always be x-1.

Sorry to hear all of your unfortunate adventures with raid 0. Raid 0 is what you use for non-critical data as once you lose the drive, thats it. Only option to recover data at that point would be data recovery.

Ciao,
Greg

Re: RAID Array

Steeve Hébert — Wed, 22 Sep 2004 13:50:31 GMT

Hi,

If I make it in two steps ???

First one : Go back to 1 disk.

Second one : Build mirror.

I'm sure that I can store all my data on 1 disk because it was like that before and I didn't add some data.

I will try to go back with the ACU.

Thanks

Re: RAID Array

Steeve Hébert — Wed, 22 Sep 2004 14:25:26 GMT

Hi,

I looked the ACU.

If I remove a disk from the RAID 0 all the data will be lose.

Question : If I add an IDE drive in the server an use Windows 2000 to make a software mirror of my RAID 0... Does it make sens ???

Thanks

Re: RAID Array

Greg Carlson — Wed, 22 Sep 2004 15:10:45 GMT

Steve,

Hi,

I looked the ACU.

If I remove a disk from the RAID 0 all the data will be lose.

Question : If I add an IDE drive in the server an use Windows 2000 to make a software mirror of my RAID 0... Does it make sens ???

I can't think of anything worse to do than this... if you must use an IDE drive to copy the data off the SCSI hdd until you can reconfigure it properly, that is one thing. The IDE hdd and SCSI hdd operate at very different performance levels and you will end up with even more problems. Stick with hardware RAID because you paid for it with your proliant. And yes, removing any hdd from a RAID 0 loses the entire raid set.

Ciao,
Greg

Re: RAID Array

Steeve Hébert — Wed, 22 Sep 2004 16:45:10 GMT

Hi,

Yes, I know that IDE disks are worse then SCSI. But it's only to backup the server. Then I will remove a drive from the RAID and put back the data from the IDE to SCSI.

Is it good ?
(Or possible with Win 2000 software mirror)

Thanks

Re: RAID Array

JohnWRuffo — Wed, 22 Sep 2004 18:18:11 GMT

Steeve:

The ProLiant ML370 does not have direct support for IDE drives. The drive likely will not boot of the internal IDE controller. Only support for CD-ROMs and such.

Re: RAID Array

Gerhard Roets — Thu, 23 Sep 2004 02:56:51 GMT

Hi STeeve

As propably stated before.

RAID0 ... is not RAID at all but one big hairy accident waiting to happen :P It is nice for true temporary non business critical no need to recover space. Performance is great for reading and writing. And it is extremely cheap on the resources/ disks to create space. If you loose ONE disc you loose it ALL

RAID1 ... is raid but it is more expensive because you need to buy double the disk. It is fast and balanced on reading and writing. You can loose half the disks if you loose the right ones. If you loose two disks in a mirror pair you loose it all(dependant on implementation).

RAID5 ... cheaper than RAID1 more expensive than RAID0. You can loose one drive in a redundancy group. It is fast on reading but slower on writing. This does depend on the implentation though.

Off course you can add hot spares to rebuild on. But the rebuild is NEVER instantaneous. So you have exposure ib the rebuild time. Adding hotspares does add to to price though.

Sorry to chip in here even though you had answers before it justs drives me up walls if some one sets up raid0 for production achines :P I had to explain this a few times ...

Regards
Gerhard

Re: RAID Array

Steeve Hébert — Thu, 23 Sep 2004 07:36:03 GMT

Hi,

A new disk is 800$.
(That's the cost of learning... )

I think that I will buy a new disk and add it to the array.

The array will then become fault tolerante.
So, if a disk of the array die, the server will continue to work...
( Correct ? )

Thanks

Re: RAID Array

Gerhard Roets — Thu, 23 Sep 2004 07:52:28 GMT

Good idea but remember a few things

not raid0! :P Alo use the hp agents to monitor your device. If a disc fails you should not now about this ... but you should get notified about it else the disc will never be replaced.

Also remember raid does not protect you from files being erased or fs/os corruption ... so raid does not replace a good backup strategy, it augments it.

Regards
Gerhard

Re: RAID Array

Greg Carlson — Thu, 23 Sep 2004 10:28:26 GMT

Steve,

When you add that $800 disk, make sure that you change raid levels from 0 to 5 instead of just expanding the array and leaving it a raid 0. Then you would still be with no redundancy.

Good luck.

I would also recommend looking at this link for some more detailed understanding of how RAID levels work.

http://www.acnc.com/raid.html