ZFS and Direct I/O

Heinz M�ller

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May 10, 2009, 1:40:07 PM5/10/09

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Hi,

after I got the information that ZFS ist not supported with raw devices
does anyone know if ZFS with file systems as database devices is supported with Direct I/O?

Today I've got a SYBASE newsletter with a PDF called
"Performance on SYBASE Decices Using Direct I/O, Dsync and Raw Partitions"
and it seems that database devices with Direct I/O is as fast as raw devices.

So I ask myself to use ZFS with filesystem as database devices and Direct I/O.

Thanks!

Heinz

Rob V [Sybase]

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May 10, 2009, 6:48:38 PM5/10/09

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ZFS does not support directIO, meaning that you'll have to use dsync=true.
As for raw devices, ZFS does provide these, albeit by emulating them; the
big downside is that only synchronous I/O is supported on these.
All in all, ZFS, either as raw devs or files, is not well-suited for using
with databases since there tends to be a performance hit. UFS files (with
directIO) or real raw devices are a better choice.

HTH,

Rob V.
-----------------------------------------------------------------
Rob Verschoor

Certified Sybase Professional DBA for ASE 15.0/12.5/12.0/11.5/11.0
and Replication Server 15.0.1/12.5 // TeamSybase

Author of Sybase books (order online at www.sypron.nl/shop):
"Tips, Tricks & Recipes for Sybase ASE" (ASE 15 edition)
"The Complete Sybase ASE Quick Reference Guide"
"The Complete Sybase Replication Server Quick Reference Guide"

mailto:r...@YOUR.SPAM.sypron.nl.NOT.FOR.ME
http://www.sypron.nl
Sypron B.V., Amersfoort, The Netherlands
Chamber of Commerce 27138666
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"Heinz M�ller" <onkel...@mscologne.de> wrote in message
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Heinz M�ller

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May 11, 2009, 12:27:18 PM5/11/09

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"Rob V [Sybase]" <ro...@DO.NOT.SPAM.sypron.nl.REMOVE.THIS.DECOY> schrieb im Newsbeitrag news:4a0759c6@forums-1-dub...

> ZFS does not support directIO, meaning that you'll have to use dsync=true.
> As for raw devices, ZFS does provide these, albeit by emulating them; the big downside is that only synchronous I/O is
> supported on these.
> All in all, ZFS, either as raw devs or files, is not well-suited for using with databases since there tends to be a
> performance hit. UFS files (with directIO) or real raw devices are a better choice.
>
> HTH,
>
> Rob V.

Rob,

thank you. I got a similiar info from SYBASE today. I'll use SDS/LVM.

Heinz

Eugene

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Oct 7, 2009, 6:13:53 PM10/7/09

to Rob V [Sybase], Max Kitgor

Rob,

Did something change since then, particularly ASE 15.0.3 ESD#2 and
new Solaris 10 versions ? Our sysadmin want to setup ZFS and all
what I have found (inc.solved cases) related ~ 6 months ago.

Regards,
Eugene

Rob V [ Sybase ]

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Oct 10, 2009, 10:46:13 AM10/10/09

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Not that I'm aware of...

HTH,

Rob V.
-----------------------------------------------------------------
Rob Verschoor

Certified Sybase Professional DBA for ASE 15.0/12.5/12.0/11.5/11.0
and Replication Server 15.0.1/12.5 // TeamSybase

Author of Sybase books (order online at www.sypron.nl/shop):
"Tips, Tricks & Recipes for Sybase ASE" (ASE 15 edition)
"The Complete Sybase ASE Quick Reference Guide"
"The Complete Sybase Replication Server Quick Reference Guide"

mailto:r...@YOUR.SPAM.sypron.nl.NOT.FOR.ME
http://www.sypron.nl
Sypron B.V., Amersfoort, The Netherlands
Chamber of Commerce 27138666
-----------------------------------------------------------------

"Eugene" <ekor...@davidsohn.com> wrote in message
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