[ZFS] Metadata Allocation Classes

[Ben RUBSON]

Hi,

Intel has pushed the "Metadata Allocation Classes" feature to ZFS on Linux.
This allows to store metadata on a so called "special" VDEV, made of SSD  
for instance.

This looks really promising.
I wrote a patch 2 years ago which pins metadata in L2ARC, at eviction time.
This really helps with some specific workloads.
But "Metadata Allocation Classes" should be one step further in terms of  
performance.

Simple question, do you plan to backport this feature to FreeBSD ?
Or do you first wait for it to reach Illumos (does not seem to be there  
yet) ?

ZoL discussion : https://github.com/zfsonlinux/zfs/issues/3779
ZoL PR : https://github.com/zfsonlinux/zfs/pull/5182

Thank you very much !

Ben