RAID5 -- rebuild time ?

Yesterday I had a SAS 15k 300GB hard drive
fail in my Dell PowerEdge 2950 RAID5 server
and it has been rebuilding for 24+ hours.

How long should a rebuild take ?

  ** I called Dell, stating that I ordered the drive from them,
       but they would not give me a rebuild time estimate.
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John TsioumprisSoftware & Systems EngineerCommented:
Normally it should take minutes...or an hour at least this was the time it took on my Dell...
Better to take a backup to be safe and inform Dell in order to get a new Drive....

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PowerEdgeTechIT ConsultantCommented:
SAS should be fast, and 300GB is not very big - I agree, an hour at most.

Which RAID controller do you have? If you have a SAS 6/iR, it could be slower, but still not 24 hours.

How are you monitoring its progress? In OMSA? If so, have you refreshed the screen? Restarted OMSA? You might try restarting all the DSM services, then re-opening OMSA to check the progress ... it could be done and just not be updating in OMSA correctly.
It could take days, or well over a week.  It depends on
 - whether or not you have a BBU and write cache enabled (if yes, it takes less time)
 - # of HDDs in the array total, as there is a bus saturation point.
 - If your o/s is booted.  You can speed things up by stopping every service and program you can so the array rebuild doesn't compete with system i/o.
But if it takes this long, and you have a relatively small array, say 4-6 disks then you are probably going through deep recovery trying to read-re-read blocks 10-20 times because you have one or more disks that have a large number of ECC errors.  

Gut feeling, based on the system you have and the capacity of the drives, it is the deep recovery I mentioned above.  I'd strongly consider replacing all the drives, or just getting larger capacity drives and going to a RAID1.  You'll be much better off in both reads and writes in most cases with a RAID1 then a RAID5 anyway.
Tony GiangrecoCommented:
I maintain multiple PE2950's and I've replaced many drives. I've seen drives rebuild in 20 minutes and others that took a few days. it all depends on the load placed on the server, if it's in a raid and the speed of the drives and controller.

I would just let it continue. If it goes past three days, then their my be a problem.  I'm assuming the new drive was an identical replacement for the failed drive? is that correct?
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