DB2 Linux settings (cache/buffers/IO)

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Jurgen Haan - 08 Mar 2007 14:12 GMT

Hi. I'm running a DB2 8.2 install on a X86_64 SuSE install.
The tablespaces and logs are stored on a netapp filer through an NFS mount.

Now I came across this article:
http://www-128.ibm.com/developerworks/db2/library/techarticle/dm-0509wright/

In that document the possibility of Direct I/O is given to improve
performance. I was wondering if this would also apply to NFS shares (NFS
being a virtual disk etc).

Furthermore, what's the best strategy to pursue on buffer allocation?
How can I best minimize the use of linux buffers? (thus increasing the
use of DB2 allocated memory?)

-R-

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dunleav1 - 08 Mar 2007 18:30 GMT

> Hi. I'm running a DB2 8.2 install on a X86_64 SuSE install.
> The tablespaces and logs are stored on a netapp filer through an NFS mount.
>
> Now I came across this article:http://www-128.ibm.com/developerworks/db2/library/techarticle/dm-0509...
>
> In that document the possibility of Direct I/O is given to improve

> performance. I was wondering if this would also apply to NFS shares (NFS
> being a virtual disk etc).
[quoted text clipped - 4 lines]
>
> -R-

Set - db2set DB2LINUXAIO=true.

Turn off file system caching.

I don't think I would have database data files on a NFS mount.

Buffer allocation depends - But I have seen good results from 1
bufferpool for each of my database page sizes and 1 for large temp
page size.

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Mark A - 08 Mar 2007 21:19 GMT

> Set - db2set DB2LINUXAIO=true.
>
[quoted text clipped - 5 lines]
> bufferpool for each of my database page sizes and 1 for large temp
> page size.

What about long tablespaces that contain LOB or LONGVARCHAR data that
do not use bufferpools, and are synchronously accessed from disk each
time?

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