ZFS Issues

[nadamson]

Hi Everyone,

I recently purchased a server from OVH that has 2 x 512Gb SSDs and 2 x 6TB HDD Drives, i installed proxmox using zfs mirror with a size of 64Gb on the SSDs.
Once proxmox was installed i then create a zpool called dpool which again is a mirror but with the HDD drives, i then created some more partitions on the SSDs to use as cache,log and special, however VMs keep freezing or timing out, i'm relatively new to zfs so any help would be appreciated.

some more context for dpool, i'm using sha512 as the checksum, dedup is enabled and compression set to lz4

 

[Dunuin]

What SSDs model came with the server? ZFS should be used with enterprise grade SSDs. Consumer SSDs, especially when using QLC NAND, can really slow down the host.

 

[nadamson]

It's come with 2 x SAMSUNG MZVL2512HCJQ-00B07 sadly, I have no control over what comes with the server as it's what OVH has provided me with

 

[Dunuin]

I wouldn`t use these SSDs as SLOG. They got the same low TBW/DWPD as a consumer TLC SSD and are also missing the power-loss protection, so sync write performance will be bad and a SLOG will do sync writes only.

 

[Max Carrara]

sha512 as the checksum

For what reason?

dedup is enabled

This might be the culprit. Deduplication is really, really, really not necessary in 99% of use cases. It sounds like something you want to have enabled, especially if you're new to ZFS, but most of the time, the benefit is negligible and not worth the CPU cost. Now that it's enabled, you probably won't be able to get rid of it completely after disabling it again, because your existing deduplicated data has to be replicated again, which will only happen if the data is modified, copied, etc.

compression set to lz4

That's fine, you can leave that on. Turning on compression actually has benefits and is basically "free".


Also, you won't need a SLOG, special device, and L2ARC unless you really know what you're doing and have a specific use case in which you'll actually benefit from using them.