Time To Rebuild RAID5

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26-11-2009, 08:23 AM
Skier

Time To Rebuild RAID5

I have a Thecus N5200 Pro with 5 x 500GB WD drives: 4 in a RAID5 with 1 as a hot spare.

I've recently had a drive showing a warning so as advertised the RAID automatically started to rebuild itself using the spare drive. The time for this rebuild was some 7,800 minutes - some 5.5 days!! Around 3 days into this rebuild the original spare drive had I/O errors and so I replaced that drive and started the rebuild again; once again the time for the rebuild is similar - over 5 days.

Is this amount of time to rebuild a RAID5 normal?

Regards

Skier
26-11-2009, 11:53 AM
crisp

Re: Time To Rebuild RAID5

Hi Skier,

I don't own a N5200 but a N7700 (which I think is even a bit older in hardware than the N5200 Pro?). Rebuilding a RAID5 array of 3x 2TB disks after replacing one of the three disks, takes roughly 10 hours when the system is under no load (as in: NOBODY using it).

I noticed that heavy I/O can even almost completely stop the build process, projecting rebuild times of over 80000 minutes (55 days??). Perhaps you can lower the IO or check if the rebuilding is faster at low IO times?

Best regards,

Crisp
26-11-2009, 04:37 PM
Skier

Re: Time To Rebuild RAID5

I have stopped the back-up process that backs up my main desktop data to the RAID and I've also stopped all modules that are installed. This means that there should be almost zero I/O. So far the build has been running for just over 16 hours, is 11% through with a projected time of 6,780 minutes still to run!

Something's not right!

Skier
28-11-2009, 09:35 AM
peterfu

Re: Time To Rebuild RAID5

There may be disc errors and therefore the rebuild takes so long.
I would backup all my data from the box.
The N7700 is a newer hardware as the N5200 and has a quicker processor and more ram.
br
Peter
30-11-2009, 02:14 AM
Skier

Re: Time To Rebuild RAID5

There are no disc errors reported on any of the discs currently in the RAID. As the Thecus N5200 Pro seems extremley intolerant of disc errors, hence the rebuilds, I don't believe this to be the case.

Regards

skier
30-11-2009, 09:54 AM
lexos

Re: Time To Rebuild RAID5

you can still upgrade the CPU to have a bit more speed and the memory as well. It helps a bit and it's not expensive.

BR

Vincent
30-11-2009, 10:11 AM
crisp

Re: Time To Rebuild RAID5

Hi Peter,

Quote:

Originally Posted by peterfu

There may be disc errors and therefore the rebuild takes so long.
I would backup all my data from the box.

I notice the same phenomenon with a new Thecus N7700 and new harddisks. IMHO this is simply an issue with the firmware that does not grant enough priority to the rebuilding process but rather to the I/O that needs to be fullfilled.