ZFS pool with a large number of filesystems

[Tenzin W. Lhakhang]

The most I have seen is approximately 10,000.

The performance isn't too bad at that scale.  The clone fs metadata becomes a bit costly.  I seen pretty deep nesting into the zfs dataset chains on certain server types; dataset clone snap clone snap chains going about 30 levels.

Note:  we are running zfs on illumos (Smartos)

General system specs are:  e5-26[89]0v2,256gb ram, 1-2 ZIL and ssd or spinning with 4-6 ssd cache drives.

Tenzin

Sent from my iPhone

> On Apr 4, 2016, at 9:15 PM, Miroslav Lachman <000.fbsd at quip.cz> wrote:
> 
> 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
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