zfs discuss - Feb 2008 - Avoiding perfromance decrease when pool over 80% usage

Hi all,

i am planning a zfs-fileserver for a larger prepress-company in Germany. Knowing
that users tend to use all the space they can get, i am looking for a solution
to avoid a rapid performance loss when the production-pool is more than 80%
used.
Would it be a practical solution to just set the quota of the pool to something
below 80% of the available space?

Regards,
Tom
 
 
This message posted from opensolaris.org

Nobody out there who ever had problems with low diskspace?

Regrads,
Tom
 
 
This message posted from opensolaris.org

+------------------------------------------------------------------------------
| On 2008-02-12 02:40:33, Thomas Liesner wrote:
| 
| Subject: Re: [zfs-discuss] Avoiding performance decrease when pool usage is
|  over 80%
| 
| Nobody out there who ever had problems with low diskspace?

Only in shared-disk setups. i.e., ZFS lives on a slice or on
partition 2 with (typically) UFS slices or UFS on partition 1.

I''ve definitely tried to keep disk util under 80% for this
reason. Things become very slow as you pass that limit.

I haven''t noticed this behavior when ZFS has (as recommended) the
full disk.
-- 
bda
Cyberpunk is dead.  Long live cyberpunk.
http://mirrorshades.org

Thomas Liesner wrote:
> Nobody out there who ever had problems with low diskspace?
>
>   
Okay, I found your original mail :-)

Quotas are applied to file systems, not pools, and a such are pretty 
independent from the pool size. I found it best to give every user 
his/her own filesystem and applying individual quotas afterwards.

-- 

Ralf Ramge
Senior Solaris Administrator, SCNA, SCSA

Tel. +49-721-91374-3963 
ralf.ramge at webde.de - http://web.de/

1&1 Internet AG
Brauerstra?e 48
76135 Karlsruhe

Amtsgericht Montabaur HRB 6484

Vorstand: Henning Ahlert, Ralph Dommermuth, Matthias Ehrlich, Andreas Gauger,
Thomas Gottschlich, Matthias Greve, Robert Hoffmann, Markus Huhn, Norbert Lang,
Achim Weiss
Aufsichtsratsvorsitzender: Michael Scheeren

Ralf Ramge wrote:
> Quotas are applied to file systems, not pools, and a such are pretty 
> independent from the pool size. I found it best to give every user 
> his/her own filesystem and applying individual quotas afterwards.
Does this mean, that if i have a pool of 7TB with one filesystem for all users
with a quota of 6TB i''d be alright?
The usage of that fs would never be over 80%, right?

Like in the following example for the pool "shares" with a poolsize of
228G an one fs with a quota of 100G:

shares                 228G    28K   220G     1%    /shares
shares/production       100G   8,4G    92G     9%    /shares/production

This would suite me perfectly, as this would be exactly what i wanted to do ;)

Thanks,
Tom
 
 
This message posted from opensolaris.org

bda wrote:
> I haven''t noticed this behavior when ZFS has (as recommended) the
> full disk.
Good to know, as i intended to use the whole disks anyway.
Thanks,
Tom
 
 
This message posted from opensolaris.org

Thomas Liesner wrote:
> Does this mean, that if i have a pool of 7TB with one filesystem for all
users with a quota of 6TB i''d be alright?
>   
Yep. Although I *really* recommend creating individual file systems, 
e.g. if you have 1,000 users on your server, I''d create 1,000 file 
systems with a quota of  6 GB each.  Easier to handle, more flexible to 
use, easier to backup, it allows better use of snapshots and it''s
easier
to migrate single users to other servers.
> The usage of that fs would never be over 80%, right?
>
>   
Nope.

Don''t mix up pools and file systems. your pool of 7TB will only be 
filled to a maximum of 6TB, but the file system will be 100% full. which 
shouldn''t impact your overall performance.
> Like in the following example for the pool "shares" with a
poolsize of 228G an one fs with a quota of 100G:
>
> shares                 228G    28K   220G     1%    /shares
> shares/production       100G   8,4G    92G     9%    /shares/production
>
> This would suite me perfectly, as this would be exactly what i wanted to do
;)
>
>   
Yep, you got it.

-- 

Ralf Ramge
Senior Solaris Administrator, SCNA, SCSA

Tel. +49-721-91374-3963 
ralf.ramge at webde.de - http://web.de/

1&1 Internet AG
Brauerstra?e 48
76135 Karlsruhe

Amtsgericht Montabaur HRB 6484

Vorstand: Henning Ahlert, Ralph Dommermuth, Matthias Ehrlich, Andreas Gauger,
Thomas Gottschlich, Matthias Greve, Robert Hoffmann, Markus Huhn, Norbert Lang,
Achim Weiss
Aufsichtsratsvorsitzender: Michael Scheeren

Ralf Ramge schrieb:
> Thomas Liesner wrote:
>> Does this mean, that if i have a pool of 7TB with one filesystem for
all users
>> with a quota of 6TB i''d be alright?
> Yep. Although I *really* recommend creating individual file systems, e.g. 
> if you have 1,000 users on your server, I''d create 1,000 file
systems with a
> quota of  6 GB each.  Easier to handle, more flexible to use, easier to
backup,
> it allows better use of snapshots and it''s easier to migrate
single users
> to other servers.
Thanks for your recommendation, still this would not meet our needs. All the
data in the production pool must be accessible to all users on this system and
will be worked on by all users on this system. Hence, one shared fs for all
users is perfectly fine.
Thanks for all your input,

Tom
 
 
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