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I have dedicated server with 4 HDD in hardware RAID 10 configuration and It worked fine until yesterday, when It started to crash randomly on couple minutes. I’ve contacted my data center and they’ve run a system diagnostics and they found that one of my HDD in the RAID 10 array was defective, they replaced the drive and it started rebuilding itself automatically. Then they’ve booted the system in normal mode and it was working normally for 15-minutes when it started to crash again. I made couple of diagnostics on my own and when I checked state of the physical drives with:

arcconf GETCONFIG 1 PD

I’ve noticed that the HDD 0,0 have S.M.A.R.T errors, I reported that to my DC and they confirmed this and requested to swap that device with new one, but they suggested me to make backup of my data (~2TB) because it’s very likely to lose my data. I’ve made backup of my data and then they replaced the second HDD. After booting they needed to make force start of RAID controller and the system booted in recovery mode. I think that they swapped the wrong drive first time because it’s highly unlikely two drives to fail at the same time in different mirror sets but that is another story to tell… My problem is that the second replaced HDD isn’t rebuilding it self. I’ve tried to clear the metadata for that drive with:


and than set the state of the drive as hot spare with


so it to begin rebuild process automatically but without success.

My RAID 10 array data is 4 HDD drives HDD 0,0 and HDD 0,1 are in mirror set and HDD 0,2 and HDD 0,3 in another.

The output from logical device state is: arcconf getconfig 1 ld

And the output from physical drive state is: arcconf GETCONFIG 1 PD

Controller status:

My questions is is there any way to make that drive rebuild it’self without loosing any data.


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Setting the first drive as a hot-spare after the fact would not be helpful in this case. – ewwhite Dec 14 '12 at 12:42
I think that they swapped the wrong drive first time because it’s highly unlikely two drives to fail at the same time in different mirror sets but that is another story to tell Not true, actually. The assumption that drive failures in a RAID array are independent events has been demonstrated to be unfounded. Once one drive fails, the odds of the others failing increase dramatically, even in a non-parity RAID set. – HopelessN00b Dec 14 '12 at 12:45
@HopelessN00b I'think that I've found the solution. The problem probably was that the new HDD was faulty or smaller by few segments than the original ones. They've swapped the "new" HDD with a newer one :) and all is running smoothly, i think. The problematic drive is rebuilding it's little strange do that the first one is finished with the rebuilding and it's Online in about 24h. Shouldn't rebuild process take more time? And should i start my server in normal mode or to wait rebuild of the disk to be done. Thanks for your help. – SkechBoy Dec 14 '12 at 13:17
I entered this question expecting to read "My RAID failed and I have no backup, HELP!" I was pleasantly surprised. – gparent Dec 14 '12 at 18:30

I think the answer may be that the adaptec controller will only rebuild 1 drive at a time.

I have an Adaptec 5805Z controller in a RAID 10 with 4 groups. We just replaced 1 drive out of each group and only 1 group is rebuilding at the moment. I know that all of the replacement drives are good because we ran badblocks on them, further, they are definitely larger than the drives they are replacing.

@SkechBoy, do you know if your first group rebuild finished before the second one started?

Update: Just received confirmation from Adaptec that the "controller will usually rebuild a segment at a time". In other words, you have to wait for the first RAID group to be rebuilt before it will start rebuilding the second one.

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Hi, I can't confirm that the rebuild of first drive was finished before the rebuild of second was started. It was rebuilding around 24h and when we added the second I think that it was interrupted as you are suggesting. Is it going to resume automatically when the second one is finished or I should start it manually? Thanks – SkechBoy Dec 14 '12 at 19:46
Per my update above, the logical volume will only rebuild 1 RAID group at a time, so you have to wait for one to finish before the second one can start. If you have "Automatic Failover: Enabled" on your controller then the second RAID group should start rebuilding as soon as the first one is finished. If not, see – jag3773 Dec 14 '12 at 20:51

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