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Very Slow Rebuild

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Hi guys

I just got back into Unraid recently and build a 20bay nas to migrating drives and data to the new NAS.

I am having inconsistent or very very long rebuild times.

My Last 2 drives i swapped out it took about 3-4 days from memory but for this one its just way to long.

Would this procedure also be faster if i moved the data from the disks being replaced out first with Unbalance?.

At the moment i had a handfull of bigger drives and will replace all the 3-6tb drives with 8TB Drives and then replace all those with 12TB+ Drives and at this rate my little exercise will take me a year plus.

Also will it be faster to replace 1 drive at a time instead of 2?

My Rebuild speed last few days has been 1-4MB/Sec

monsta-nas-diagnostics-20221101-1227.zip

 

I would like to thank everyone in advance.

Also, if you find the issue, please let me know how to identify it in the future.

Solved by JorgeB

  • Community Expert
  • Solution

There's something writing to the array during rebuild, disks 2 and 3 are being rebuilt while there are writes to disks 1, 6, 7, 8 and 9, this will make the rebuild (and writes) extremely slow.

  • Author

I am Migrating data from multiple Synology 8 bay units. But you seem to be correct.

This morning 1 mirror task finished at some point and rebuild time went back to about a day or so.

So would it be fastest to turn off everything during rebuild? Including Docker etc?

  • Community Expert
1 hour ago, DeNNii said:

So would it be fastest to turn off everything during rebuild? Including Docker etc?

Any other drive activity during a rebuild will adversely affect the performance of the rebuild so avoiding it if at all possible is highly desirable.

  • 1 year later...

Sorry I'm coming back to this topic because for a few days I had a problem with a disk that died, after replacing it (with a used hard disk) I noticed that the data rebuild was going very slow so instead of 50-60 mb/sec, it was going at 2.5 mb/sec. So I thought the problem was the HP H240 controller, so I bought a new one, disabled RAID and installed it, however even now with the new controller it is still going slow at 2.5 MB/sec: 


Estimated speed: 2.5 MB/sec 
Estimated finish: 27 days, 19 hours, 58 minutes 

 

I attach the diagnosis file.
Thanks for anyone who can help me! 
 

tower-diagnostics-20241020-2150.zip

  • Community Expert

Nothing obvious logged, run the diskspeed docker test to see if the disks are performing normally.

I bought a 6tb drive identical to the others I already own, and now everything works like a charm. 

 

Total size: 6 TB 

Elapsed time: 17 minutes 

Current position: 117 GB (1.9 %) 

Estimated speed: 113.2 MB/sec 

Estimated finish: 14 hours, 26 minutes 

 

Now I would like to understand what happened to that broken hard disk.

Obviously I unplugged it from my unraid server, however I am asking how I can do a complete disk check and related repair (if possible) from another pc where I have both a windows and ubuntu. Can I do this? I would not want to throw away the disk....

 

Thank you very much for the prompt disposition last night! 

  • Community Expert

Run the diskspeed docker test on that disk.

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