# Dell Server RAID Controller failure



## PhilGT (Nov 24, 2010)

I have a Dell PowerEdge 2950 running two RAID 1 partitions. 

The RAID controller has failed on me and therefore broken the mirror. The server is now running on 1 disk of each original partition. 

Is there any way that I can rebuld the RAID without losing the data on the live server? I have another 2950 ready to go with a working RAID controller. The server runs 24/7 and it is impossible to get a large maintenance window. My initial thoughts were to take an image of the current data and simply restore this image onto my other newly built 2950 with working RAID. The downside of this is that I lose data changes between taking the image and getting the restored image server back online. 

Is there any way I can shut the server down on it's current configuration and rebuild a RAID array from the current live disks so that it creates a new mirror?


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## Wand3r3r (Sep 17, 2010)

I would question that it is the raid controller that has failed. If it had you would have no drive access period.

Have you tried going into the controller and rebuilding the raid?


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## PhilGT (Nov 24, 2010)

Yes, ok the RAID controller shows the two virtual disks, both RAID 1. When I click in to each virtual disk there is only one disk there, ie the working one. The RAID 1 status shows degraded but normally you can still see the working disk say in slot 0 and then the degraded disk in slot 1 etc. However in my example each Virtual disk array only contains one disk. The RAID controller failed in the original server so I had to move the disks into an identical Poweredge 2650. The server boots ok but only runs on two disks, not 4. 

Is there any way I can rebuild the two RAID 1 Virtual disks without losing data? If i plug in two blank disks I am assuming it wont rebuild - it will only allow me to use the disks as unassigned and build a new array out of them? Any ideas?

I could also take a physical image of the server in its state and restore to another identical power edge 2650 with a new working RAID but the server runs 24/7 so its a nightmare to get downtime. 

I know the RAID controller failed on the original PE2650 as at boot sequence it hangs on the starting raid controller bit.


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## Wand3r3r (Sep 17, 2010)

"The server boots ok but only runs on two disks, not 4. "

That is not sounding like a mirror set but a raid 10 [a stripe of mirror sets] if the original had 4 disks. Or perhaps you had just two mirrors and lost a drive in each [more likely]. 

This also explains why you aren't seeing a rebuild. These disks were never mirrored with each other.

In Disk Management is the OS on one volume and Data on another? Not a single disk with two partitions?

If this is two mirror sets than putting the two additional drives in and mirroring each is the way to go.


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## PhilGT (Nov 24, 2010)

Yes, you have got it in one. 

My original config was OS on one volume (one Raid 1 partition) and Data on another volume (Second Raid 1 partition). So as you state, I have lost one disk in each Raid 1. 

Again, these disks were not mirrored with each other, rather they were mirrored with another disk each but the mirror broke. So yes,originally two mirrored sets, one for OS and one for Data. 

So are you saying that if I put in two blank disks of similiar or larger volume I can mirror the current live volumes onto these? I do not have the other two original disks as they have disappeared before I started in the job. 

Currently then I still have two Virtual Disks but each one is missing its mirror. When I click on the Virtual disk only one disk is shown. It doesnt even show that there is a disk missing. I just wanted to be sure how the system would behave when inserting a two new blank disks. Can I assign a blank disk to be added to each current virtual disk and it then mirror off the current live data in Dell OMSA?


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## Wand3r3r (Sep 17, 2010)

You are right on the money. Yes add the disks and mirror each. You maybe able to do this without taking down the server with the perc software on the server. Been quite awhile since I worked with a dell server [doing mostly hp these days]


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## PhilGT (Nov 24, 2010)

Ok super thanks. Gonna try it tomorrow. Will let you know how I get on.


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## PhilGT (Nov 24, 2010)

Ok so I put the disks in and nothing happened. I was unable to start a rebuild even manually in omsa. Does this mean I need to boot the server into the raid bios. Is it even possible to setup new raid 1 mirrors with one working disk and the new blank one? Will it not just wipe all data when I create a new mirror set?


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## Wand3r3r (Sep 17, 2010)

when you added the disks did you initialize them? That is usually the first step.
next step is to add the additional disk as a hot spare available to one array. Doing so should start an automatic rebuild since the mirror set is already degraded.

You should be able to manually remirror. Trick is identifing the existing mirror single drive by its controller channel/drive id. You mirror it to the new disk not the other way around or you end up with a data free array.

Backup first.


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## PhilGT (Nov 24, 2010)

I did it all with the server running and in Dell OMSA the disks I put in didnt show up anywhere. In newer hardware like you mention I can normally initialise at this stage. As I am working on a 4 or 5 year old PE 2650 perhaps then I need to carry out the initialising from the RAID Controller BIOS. This as you know means I need to reboot the server. Then when I boot back into Windows the OMSA will show the disks and allow me to assign a hot spare. Either way I will have to do this around 4am at some point this week. My downtime window is only 1am to 6am each night so I will have to just do it then. I cannot reboot the server during the day.


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## Wand3r3r (Sep 17, 2010)

Good luck PhilGT. I suspect you are right the disks need to be init-ed via the bios before being seen.


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