Right RAID Settings with Proxmox 5

[starnetwork]

Hi,
most of our servers have 6-8 SSD Hard drives with RAID Controller that include 1GB-2GB Cache
now, the question is what is the recommended configuration for Proxmox 5
focus on Availability and best performance:
1. Hardware RAID 10?
2. ZFS with RAID10?
3. Hardware RAID1 with ZFS Raid0?
4. Hardware RAID0 with ZFS Raid1?
another configuration?

Regards,

 

[Rhinox]

Never do combination of hardware and software raid (3, 4). Either hw-raid (you'd better not use ZFS then), or software raid...

 

[starnetwork]

OK,thanks!
but what is better, use the WH Raid with Controller and Cache or use ZFS with Software RAID?

 

[Rhinox]

I'm using both solutions and all I can say is: both HW-raid and SW-raid (ZFS) has advantages and disadvantages. I do not dare to say what is definitely better...

 

[LnxBil]

but what is better, use the WH Raid with Controller and Cache or use ZFS with Software RAID?

You have to ask yourself:
Do you want to have snapshots and incremental backups/replication? If not, use HW raid.

 

[starnetwork]

sure I want to have, the question is if the "cost" of using Software raid in Performance / reliability is high...

 

[LnxBil]

question is if the "cost" of using Software raid in Performance / reliability is high

It's as always: features vs. raw power. I'd always go with ZFS instead of a hardware raid controller because of the better integrity checks (your data will be more save with ZFS - silent data corruption) and features like compression, copy-on-write, snapshots, send/receive etc.

With regard to performance, this depends on so many things that you cannot answer it in general. There will always be cases in which a hardware raid controller is faster and vice versa. But a few things to keep in mind: There are scenarios in which besides a bigger software stack on the ZFS side, data can be written faster to disk because of its compressability. Hardware (I/O and CPU) is very fast nowadays, that you can do compression transparently and be faster than raw, uncompressed power, so that compressing a 1 MB block into e.g. 512 KB and storing it to disk takes less time than storing the full 1 MB block uncompressed. Besides the performance advantage, you'll also use less space.

I think that it is very hard to see any performance benefits for a RAID Controller in a full SSD setup with 1-2 GB of cache. I tried it 3 years ago and the raw throughput of my 6 Enterprise grade SSDs is 2,5 GB/sec and I had a controller with 1 GB of cache and BBU. I could no see any benefits in comparison to speed in a RAID10 setup.