Usage during Parity-Sync / Data Rebuild

[Steve Burridge]

I have finally bitten the bullet and replaced two x 4TB parity drives in my development unraid box with two x 8TB parity drives.

I am currently sitting at 57% of the Parity-Sync operation; therefore all 25+ 4TB data drives are now sat in standby whilst the remaining capacity of the larger parity drives are zero'ed.

 

Common sense is firmly telling me to wait until the Parity-Sync completes and protection is restored across the array of data drives before transferring any additional data to the box... however I somewhat have the need to do so as I do not have the required storage available outside of unraid...

 

Interested in your views... have any of you been in similar situations... what would you do?  

[itimpi]

It is probably safe to do so as the parity build has gotten past the 4TB point so even if a 4TB Drive now failed you have sufficient parity to rebuild it correctly.
 

The array will work correctly even though the parity sync is still running.    However note that any write operations will run much slower than normal as you get the parity drives having to continually move the heads between the location on the data drives being written to for new files and the point the parity sync has reached.   The sync will also run much slower while writing new array files.

 

Reading should work at normal speed as the parity drives are not involved in typical read operations.

[Steve Burridge]

Thank you itimpi, I had not considered that the incomplete parity (complete in-terms of data coverage as you point out) would be usuable in the event of issues.

 

The parity sync is now at 77% and due to finish within the next 3 hours... however I'm confident enough to begin transferring the new data now.