Windows 2008 R2 Locigal Drive Partition Missing

We have a Windows 2008 R2 server with a RAID 5 array. It is configured into one virtual disk. This disk is split into 2 partitions, C: for the OS and applications and D: for some file shares.

This weekend I got a call that employees could not access the file shares. I restarted the server remotely and that did not help. When I went into Disk Management I found that the logical partition that was D: was gone.  I have since recreated it and restored the data but would like to know what could have caused the partition to go missing. I checked the controller logs and Windows event logs and nothing stands out.

Does anyone have any ideas?
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entceeAsked:
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David Johnson, CD, MVPOwnerCommented:
need more information on your raid i.e. hardware/software any bad disks, are you using enterprise disks?
entceeAuthor Commented:
It is a perc 6/I controller with the latest firmware/driver. We are using all enterprise disks with none of them bad. I would assume if a disk was bad the array would be degraded and would not lose one partition.
noxchoGlobal Support CoordinatorCommented:
Do you mean by logical - a logical partition inside the extended partition? I would not use logical partitions on a drive which has only two partitions. For your needs two primary partitions should be enough.
The reason why this partition disappeared - either someone has deleted it or the partition record from MBR got corrupt and the Windows could not access it or see it. Usually in this case the data is there and the partition is there but it will not be shown in Disk Management or in Windows Explorer. Only special tools can restore it then.
How to avoid this? Check with CHKDSK /f the partitions for errors from time to time.
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entceeAuthor Commented:
Yes, logical in an extended. The extended was still there. I was thinking the same thing (using only primary partitions), however Windows would not allow me to create a primary partition even after deleting the extended partition that was still there. I said 2 partitions to make is easier, there are actually 4: OEM partition, Recovery partition, C and D. I know there can be 4 primary partitions so I am not sure why it would not let me create the 4th primary. I have already restored all the data so it will have to stay as a logical partition for now.

I know the partition was not deleted by a person and I think you are right about the MBR getting corrupt, it makes sense and that is exactly what I suspect happened. I am just trying to figure out the root cause. e.g. If it is the controller going bad, we will replace it.
pjamCommented:
have you run the Smart Array diagnostics?
could be a bad cache battery.
noxchoGlobal Support CoordinatorCommented:
You can create the fourth primary partition via Diskpart.exe. Try it from the command line.

Concerning the corruption, make sure that firmware of the controller is up-to-date and the hard drives are tested for bad sectors.
entceeAuthor Commented:
@pjam, I have not run the Smart Array diagnostics. Sadly, I have not heard of that. A quick Google search shows that is an HP tool, this is a Dell server (should have mentioned that earlier). Even if the battery dies, the RAID configuration is stored on the disks as well, right?

@noxcho, the data has already been restored and it is all back up and running so I am not going to change it.  The latest firmware/driver are being used.  I can check for bad sectors this weekend.
entceeAuthor Commented:
I should also add that in OpenManage, all 6 disks show "No" for Failure Predicted.
noxchoGlobal Support CoordinatorCommented:
@noxcho, the data has already been restored and it is all back up and running so I am not going to change it.  The latest firmware/driver are being used.  I can check for bad sectors this weekend.
I meant if this happens again.
pjamCommented:
HP also makes a 6i controller LOL
entceeAuthor Commented:
Gotcha. If it happens again, I will be hard pressed to find out the exact cause so it can be fixed. Fingers crossed that it was just a fluke.

Can I ask why you don't recommend using the extended/logical partition?
entceeAuthor Commented:
pjam, I am curious about your comment about the battery.  The status for the battery shows ready so it looks OK, but what if there was a hiccup with the battery? Would the controller try to use the configuration on the disks? And would a hiccup with the battery cause a partition to be deleted while the server was running?
pjamCommented:
The main issue I have had over the years with my Proliant servers is a bad battery or battery cache.  Replaced three in the past four or so years.  They call them BBWC Cache Module, either 256MB or 512MB.  Even my HP StorageWorks MSA20 has them.
I do not know if Dell has similar but would assume so.
Back when I still used Dells in the era of PowerEdge 4400 and Netware I had an issue with dirty VRAM that completely wiped my server, was not fun.

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pjamCommented:
So entcee, what was it finally?
entceeAuthor Commented:
I can only speculate.  We ordered a new battery since that is a cheap and easy thing to proactively do.  I will have to keep an eye on things, hopefully it does not happen again.
entceeAuthor Commented:
Well, about a year and a half later, it did it again.  Same thing, same server.  Really wish I knew what caused this!
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