Flash Storage​

William Jansen Van Nieuwenhuizen posted 11-02-2020 16:33

Hello

 

In that case the disks wont spare out. Once the new disk is replaced it should do a correction copy to the new disk(recreate the data from parity).

 

It's better from a risk perspective to at least have a spare disk per drive type. Best to check with the configuration tool on the best practise and reccomended disks.

Kurniawan Septian posted 11-02-2020 16:38

While the disk is not replaced yet, what happen to the parity group?

Does the data on the parity group still accessible?

William Jansen Van Nieuwenhuizen posted 11-02-2020 17:13

Yes the data is still accessable, but with degrated performance. As reading the data on the failed disk, is being recalculated from parity. IE 7 disks are read in order reconstruct the failed data on 1 drive. Where under normal circumstances the data would just be read from 1 disk.

Kurniawan Septian posted 02-02-2021 02:19

How bad is the degraded performance? what percentage of performance drops because of it?

William Jansen Van Nieuwenhuizen posted 02-02-2021 08:50

It depends on a number of things, The RAID level you're using, the number of disks in the parity group ect. Best might be to google something like 'raid rebuild performance impact calculator' fill in your configuration and see what the impact would be.

Also remember you will most likely only mark performance degredation on non cache hit reads. Since write's typically always go to cache.

Karan Patani posted 11-04-2022 08:45

not sure if this is still relevant but to add what William mentioned is what application is running on the degraded Raid Group. It would be a mix bag scenario with the application, and hardware configuration along with the RAID and disk type.

Debdatta Chattopadhyay posted 11-07-2022 05:20

If you are using RAID-6 which can withstand 2 drive failures, you may still be good with no spare if luck permits. However, RAID groups wit failed drives will have lower performance.