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January 18th, 2019 05:00

Unity 400 Disk Resynchronizing

Hi.  I just replaced my first ever failed hard drive in my Unity 400 yesterday.  The disk which was replaced was a 6TB 3.5inch NL-SAS 12Gbps in a RAID 6 with seven other drives and then a hot spare.  So the whole thing is nine drives with one as a hot spare.  Presently there is 15TB used in the raid.  Anyway, the drive has been showing that it has been resynchronizing for almost 24 hours.  Is this normal?

January 18th, 2019 07:00

I also just chatted with support and they said the same thing after a webex and checking the array.  The disk is large and will just plainly take a long time.  It went from 21% to 22% during the time we were watching it.

I ended up getting commands to check it for myself so I can keep an eye on it.

To check on the resynchronization (rebuild) process of a hard drive in the Unity follow the KB provided above.

January 18th, 2019 06:00

Alright thanks.  I'll check this out.

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239 Posts

January 18th, 2019 06:00

Hi @All2surreal,

Might be yes. NL-SAS are the slowest drives, and they are "large" so potentially a lot of data to copy.

On top of that, rebuilds are background ops, therefore their speeds will vary depending how busy this RG is. If very busy with normal IO, then rebuild will be slower.

If you are worried that it is not progressing, check progress with this KB: https://support.emc.com/kb/503800

If not progressing, open a SR with support so we can take a look

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August 30th, 2019 07:00

Hi, 

I had a 6TB disk fail and it took 4 days to rebuild. The weird things is the array has only just been put into production and only had 1 x 30GB VM running. I have 46 disks spread across 3 tiers. The Lun the VM is running on was only in the Extreme Tier so Performance/Capacity tiers should be empty. Why would it take 4 days to rebuild the disk if there was no load on the array(1 VM on a 100TB array) with no data to rebuild ?

 

Knowledge transfer would be much appreciated.

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