[zfs-discuss] One dataset per user?

Arne Jansen
2010-06-22T20:14:45Z

Arne Jansen wrote:
> Paul B. Henson wrote:
>> On Sun, 20 Jun 2010, Arne Jansen wrote:
>>
>>> In my experience the boot time mainly depends on the number of
datasets,
>>> not the number of snapshots. 200 datasets is fairly easy (we have
>7000,
>>> but did some boot-time tuning).
>>
>> What kind of boot tuning are you referring to? We''ve got about
8k
>> filesystems on an x4500, it takes about 2 hours for a full boot cycle
>> which
>> is kind of annoying. The majority of that time is taken up with NFS
>> sharing, which currently scales very poorly :(.
>
> As you said most of the time is spent for nfs sharing, but mounting also
> isn''t
> as fast as it could be. We found that the zfs utility is very
> inefficient as
> it does a lot of unnecessary and costly checks. We set mountpoint to legacy
> and handle mounting/sharing ourselves in a massively parallel fashion (50
> processes). Using the system utilities makes things a lot better, but you
> can speed up sharing a lot more by setting the SHARE_NOINUSE_CHECK
> environment
> variable before invoking share(1M). With this you should be able to
> share your
> tree in about 10 seconds.

I forgot the disclaimer: you can crash your machine if you call share with
improper arguments if you set this flag. iirc it skips a check if the fs
is already shared, so it cannot handle a re-share properly.

>
> Good luck,
> Arne
>
>>
>> Thanks...
>>
>>
>
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