Is it possible to backup data monthly using unRAID parity feature?

[haeho]

When unRAID has a parity disk, it can perform parity reconstruction and recovery on the failed data disk in the array. Can this feature be used to periodically back up specific data? Here are some of my thoughts:

 

PS:

 

- My English is not very good, there may be inaccurate expressions in some places, please forgive me.

- We will not discuss other backup solutions for the time being, but only discuss the above backup methods.

 

Array situation:

 

 - 1 piece of 12T parity disk

 - 3 piece of 12T data disk

 - 1 piece of 16T backup disk (unallocated device mount)

 

Disk Data Distribution:

 

 - disk1 parity disk

 - disk2 movie

 - disk3 TV series

 - disk4 data

 

Shared folder settings:

 

 - Set the shared folder (datas) to only be written to disk4.

 

Agreement:

 

 - Assume that the disk4 (old_disk4) has been backed up with the 16T backup disk mounted on Unassigned Devices before executing parity rebuild.

 - Assuming data loss for movies/TV shows can be tolerated.

 

Backup operations at the end of each month:

 

 - Perform a Mover operation to move all cached data into an array.

 - Stop the array after confirming that the Mover data is normal.

 - Take out the disk4 (old_disk4) disk and Unassign, then boot in maintenance mode.

 - Stop array.

 - Insert the new disk4 (new_disk4) disk to replace the old disk4 (old_disk4), start the array for parity rebuild.

 

Questions and Discussions:

 

 - Is it feasible to use the parity rebuild mechanism for backup?

 - Is there some data error after rebuilding?

 - Some other issues that may arise...

 - Advantages and disadvantages compared to other backup methods

[Kilrah]

This makes no sense, you would lose array protection while you're doing that, start/stop the array and put your data at risk through configuration changes, and it would take way longer than to just rsync your drive to the one in UD while everything is running normally...

Edited December 16, 2022 by Kilrah

[haeho]

2 hours ago, Kilrah said:

This makes no sense, you would lose array protection while you're doing that, start/stop the array and put your data at risk through configuration changes, and it would take way longer than to just rsync your drive to the one in UD while everything is running normally...

 

Yes, there is a risk of data loss if another disk fails during the rebuild. But we have stated in the agreement before that the loss of movie/TV series data can be tolerated.

 

I guess I need to explain why this backup method is considered:

 

 1. Under normal circumstances, I will check the parity of the array on a monthly or regular basis, and the problem of disk loss may still occur during the parity check.

 2. Since regular parity checks are taken, compared to parity rebuilds, the pressure on the disk should be equal.

 3. If the parity rebuilds fails, the datas shared folder still has two complete data backups (16T backup disk mounted on UD and old_disk4).

[Kilrah]

1 hour ago, haeho said:

1. Under normal circumstances, I will check the parity of the array on a monthly or regular basis, and the problem of disk loss may still occur during the parity check.

Disk loss during parity check isn't a problem, it only would if parity had errors but it's not supposed to have any. No difference to be in the middle of a check or not.

 

  

1 hour ago, haeho said:

 2. Since regular parity checks are taken, compared to parity rebuilds, the pressure on the disk should be equal.

But now you have to do a check AND a rebuild.

 

Your method includes downtime, disk swaps, time with no protection, a complete rewrite of the backup instead of a simple update that would take a fraction of the time, and all that for zero benefit.

Edited December 16, 2022 by Kilrah

[haeho]

Sorry for the late reply,thanks for your suggestion, I will continue to use rsync for backups. Thanks again.

[MrGrey]

On 12/15/2022 at 11:56 PM, haeho said:

Can this feature be used to periodically back up specific data?

 

I'm late too... Parity is only meant/used to have services continue to run when there's a true/real HD failure. Backups are everything and rsync is the best. I wish Windows had rsync, but that would ruin everything that Microsoft has planned to make our lives better.

 

MrGrey.