Re: {* 05.00 *}Re: Desperate with 870 QVO and ZFS

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From: Stefan Esser <[email protected]>
To: mike tancsa <[email protected]>,
 Bob Friesenhahn <[email protected]>, [email protected]
Cc: [email protected], [email protected],
 Freebsd performance <[email protected]>
Message-ID: <[email protected]>
Subject: Re: {* 05.00 *}Re: Desperate with 870 QVO and ZFS
References: <[email protected]>
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In-Reply-To: <[email protected]>

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Am 06.04.22 um 22:43 schrieb mike tancsa:
> On 4/6/2022 4:18 PM, Bob Friesenhahn wrote:
>> On Wed, 6 Apr 2022, [email protected] wrote:
>>>>
>>>> WE DON'T USE COMPRESSION AS IT'S NOT SET BY DEFAULT. SOME PEOPLE SAY=
 YOU
>>>> SHOULD HAVE IT ENABLED.... BUT.... JUST FOR AVOID HAVING SOME DATA
>>>> COMPRESSED SOME OTHER NOT (IN CASE YOU ENABLE AND LATER DISABLE) AND=

>>>> FINALLY FOR AVOID ACCESSING TO INFORMATION WITH DIFFERENT CPU COSTS =
OF
>>>> HANDLING... WE HAVE NOT TOUCHED COMPRESSION....
>>
>> There seems to be a problem with your caps-lock key.
>>
>> Since it seems that you said that you are using maildir for your mail =
server,
>> it is likely very useful if you do enable even rather mild compression=
 (e.g.
>> lz4) since this will reduce the write work-load and even short files w=
ill be
>> stored more efficiently.
>>
> FYI, a couple of our big zfs=C2=A0 mailspools sees a 1.24x and 1.23x co=
mpress ratio
> with lz4.=C2=A0 We use Maildir format as well.=C2=A0 They are not RELEN=
G_13 so not sure
> how zstd would fair.

I have got much better compression at same or less load by use of zstd-2
compared to lz4.

Perhaps not typical, since this is a dovecot mdbox formatted mail pool
holding mostly plain text messages without large attachments:

$ df /var/mdbox
Filesystem        1K-blocks    Used      Avail Capacity  Mounted on
system/var/mdbox 7234048944 9170888 7224878056     0%    /var/mdbox

$ zfs get compression,compressratio,used,logicalused system/var/mdbox
NAME              PROPERTY       VALUE           SOURCE
system/var/mdbox  compression    zstd-2          inherited from system/va=
r
system/var/mdbox  compressratio  2.29x           -
system/var/mdbox  used           8.76G           -
system/var/mdbox  logicalused    20.0G           -

Regards, STefan

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