Benchmark-Request for ZFS 0.8 allocation classes

[LnxBil]

Hi all,

has anyone already tried out the new allocation classes with spinners and SSD for e.g. metadata and can give benchmark results? What about the Proxmox Staff, have you tried it yet? The interest may be huge if you consider that we saw 10+ threads this year alone with "slow ZFS"-related topics on the forums.
Unfortunately, I haven't enough hardware lying around at the moment to give it a proper trial, but maybe someone can jump in.

Best,
LnxBil

 

[fabian]

no hard numbers (yet ), but it should give a nice speed boost for things like:
- file servers
- containers
when you have lots and small files, or work loads where you create and delete files very often (for all of those things, you have lots of metadata operations).

keep in mind that you need two or three SSDs to not lose redundancy compared to the rest of the pool (unless you are running without redundancy there as well ), since special devices actually store data that is not stored elsewhere!

 

[LnxBil]

In the mean time, I build my first server with two enterprise SSDs for allocation classes and the OS itself and two vdevs consisting of 3 drives in raidz1 and it is noticeable faster than before, but I did not do a benchmark. Allocation classes are really great. You can create datasets and force them to the fast storage so that you will e.g. boot your OS from the SSD while all beeing part of only one pool. All metadata actions like listing of filesystems and snapshots is almost instantaneous.