ZFS pool with a large number of filesystems

[Miroslav Lachman]

Wim Lewis wrote on 04/05/2016 02:38:
> I'm curious how many ZFS filesystems are reasonable to have on a single machine (in a single zpool). We're contemplating a design in which we'd have tens of thousands, perhaps a couple hundred thousand, filesystems mounted out of the same pool. Before we go too far into investigating this idea: Does anyone have real-world experience doing something like that? Is it a situation that ZFS-on-FreeBSD is engineered to handle with good performance? Is there a rough estimate of the resources consumed per additional filesystem (in terms of kernel VM and disk space)?
>
> Thanks for any insight or advice (even, or especially, if the answer is "that's crazy, don't do that" :) )

I donn't know about how many filesystems but I know that few hundereds 
of snapshots can make a noticeable slowdown for some zfs operations.
  I think that basic "zfs list" will be painfully slow with tens of 
thousands of filesystems.

Miroslav Lachman