Storage Spaces Double Parity (slow!)

[mbroeken]

Landing here for some advise on what settings would be optimal for a new Veeam Dedicated Backup Server we are building:

Specs:
SuperMicro Box with LSI 2308 Controller + 8x 4TB hot swap SAS. (2012R2 with Veeam v9.
We would love to go for one storage space with two double parity volumes. We did some testing with
Parity - formatted with 32k Unit size - enable LargeFRS. Slow, around 50-60MB/sec writes
Double Parity - Formatted with 32k Unit size - enable LargeFRS. Very Slow, around 40-50MB/sec writes
Mirror - Formatted with 32k Unit size - enable LargeFRS. Very Good Speed, around 350 - 450 MB/sec writes.

We would ideally love to go for Double Parity so we could lose 2 disks and have acceptable amount of TBs but the writes speeds are very very bad.
Anyone have a clue why? CPU load on the system in very low. we have enough memory in place (32GB).
Looks like a small amount of memory is used for caching. when we copy files, the first 30 seconds the write speed is 250MB.sec. when memory fills up the write speeds drops to around 30-45 MB/sec. not acceptable

Any Advise?

[lando_uk]

Its just the nature of the beast, you need RAID10 if you want decent performance. If you're getting 50MB/s writes on synthetic benchmarking, just wait until Veeam has to do some transformations (synthetic full's, reverse, inc with rollbacks...) It'll be painful.

I'm not sure many people use storage spaces for their repositories, as they are add no value without the SSD Tier. And adding the SSD's would do little for backup performance.

[nmdange]

I wouldn't recommend using parity storage spaces, as your testing shows it is very slow compared to mirror spaces. You want to use a hardware RAID controller to get decent write performance with RAID 5 or RAID 6 (with more drives RAID 50 or 60 would work too). The LSI (now Avago) MegaRAID 9361-8i should be a good choice.

[ptoro]

IF you want parity then just go with a hardware RAID card and don't waste your time with storage spaces. The big thing with storage spaces IS two way and three way mirroring AND JBODS. If your goal is something to the likes of RAID10 then two way mirroring will do but parity (RAID 5, RAID 6).... you can't beat hardware RAID and parity.

[ptoro]

Also remember rebuild time if something goes wrong....

RAID 5/6 rebuild time on 8 x 4TB virtual disk would be a lot more than RAID10 OR two way mirroring

[mbroeken]

Thanks Guys. Makes sence.

I was just wondering if anybody here was using double parity on storage spaces. But I guess it does not make any sense to use it.