Re: Linux buffer cache monitoring
- From: "Christo Kutrovsky" <kutrovsky.oracle@xxxxxxxxx>
- To: Brandon.Allen@xxxxxxxxxxx
- Date: Wed, 3 Sep 2008 10:51:38 -0400
Allen,
Raw devices are just as easy to setup in virtual environments as file
systems. It's just a LUN without a filesystem created on it.
You may have to setup /dev/raw mappings, because block access devices
are also cached in linux unless you open them with direct IO flag. But
if you can open block devices like that, you should be able to open a
file as well.
You can also create "virtual" raw devices with files on the
filesystem, but I haven't checked whether those will be cached or not.
DirectIO is your best bet.
p.s.
why not test directly from Oracle? Just do a index lookup in a loop
with several sessions.
On Fri, Jul 25, 2008 at 4:21 PM, Allen, Brandon
<Brandon.Allen@xxxxxxxxxxx> wrote:
> Hi Henry,
>
> I've never used Direct I/O on Linux, but I'll look into it. I don't see
> any options with the Orion utility to force it to use direct I/O, but
> maybe there is a filesystem mount option I can use to force it similar
> to the cio mount option on AIX.
>
> I considered using raw devices to test too, but my sysadmin is telling
> me that is difficult/impossible to setup because this is actually a
> virtual environment, running on top of Win2K8 HyperV, which is one
> reason why I want to make sure we're getting sufficient IO throughput.
>
> Thanks,
> Brandon
>
>
> -----Original Message-----
> From: Henry Poras [mailto:henry@xxxxxxxxxxxxxxx]
>
> I forget if it can be used with
> Direct I/O.
>
> Privileged/Confidential Information may be contained in this message or
> attachments hereto. Please advise immediately if you or your employer do not
> consent to Internet email for messages of this kind. Opinions, conclusions
> and other information in this message that do not relate to the official
> business of this company shall be understood as neither given nor endorsed by
> it.
>
> --
> //www.freelists.org/webpage/oracle-l
>
>
>
--
Christo Kutrovsky
DBA Team Lead
The Pythian Group - www.pythian.com
I blog at http://www.pythian.com/blogs/
--
//www.freelists.org/webpage/oracle-l
Other related posts:
