Is dual parity necessary?

[superloopy1]

Guys, i'm re-assessing my drive allocations across two servers. The second server is a full backup of server 1 approx 130TB using the smaller. older drives freed up whenever i'm able to upgrade on server 1 so it follows that my backups are spread across a  larger number of these drives than the main server. So ... i protect them with dual parity 2 x 10TB drives. But, the more i think about this the less i see a need for BOTH drives, one maybe but not both, or maybe even no parity drives given that this is a backup only, what are your thoughts on this? Worst, worst case scenario ... if EVERY drive fails i could just rebuild from server 1, yes? Would take time (and cash!) so is it just the physical effort i'd need for rebuild time that parity drives are saving and do i really need two cos i sure yould use some extra 10TB drives in my system just now!!

Edited February 1, 2022 by superloopy1

[JonathanM]

Given that

a. Each drive in Unraid is independent, so losing multiple drives still leaves all the others readable

b. The data you are storing is a second copy

I'd be inclined to not run any parity on the backup server.

 

Parity isn't backup anyway, it's high availability so you can continue to use the server while you replace the drive. So keep parity valid on the main box, and don't worry about it for the backup server.

 

Just my opinion. Worth exactly what you paid.

[superloopy1]

10 hours ago, JonathanM said:

Given that

a. Each drive in Unraid is independent, so losing multiple drives still leaves all the others readable

b. The data you are storing is a second copy

I'd be inclined to not run any parity on the backup server.

 

Parity isn't backup anyway, it's high availability so you can continue to use the server while you replace the drive. So keep parity valid on the main box, and don't worry about it for the backup server.

 

Just my opinion. Worth exactly what you paid.

Thanks ... i'm inclined to agree now that i'm short of drives and have time to think about it.

 

From a recovery point of view its down to whether i 'like' the idea of one parity disk just in case so maybe i'll drop down to one and then in a couple of months time i'll reclaim that remaining one.  The original intention when i set these two servers up was to be able to flip flop them to keep the servers and disks active so from that point of view dual parity seemed a necessity. But thats long gone now and now i have a full backup, maybe i need another copy, three copies seem a good idea, that should be sufficient fallback. Mind you they all live together so maybe any efforts should be put into relocating a third server .... another project!

Edited February 2, 2022 by superloopy1

[superloopy1]

Took a while, but I have repurposed the second parity drive for the short term. Given the amount of time it took to do I think i'l leave well alone for now. Thanks.