Re: ramfs or ram disk

From: kyle Hailey <kylelf_at_gmail.com>
Date: Tue, 27 Aug 2013 13:22:21 -0700
Message-ID: <CADsdiQhUxXN1tpw5=Nhd8h7oE_TtQuNJ9_BJMrmpe2gq9oeybQ_at_mail.gmail.com>

Awesome response Connor :)
Has anyone looked into how the writes are done for temporary?

I've noticed on some AWR reports the temp read times at 0ms, for example

Event                        Waits        %Time -outs     Total Wait Time
(s)     Avg wait (ms)   Waits /txn
direct path read temp   317,082               0.00                       1
              0                      3.80

Over 300K temporary reads and the average time is 0 ms ?? How would that happen? What if the temporary data was in the Unix file system cache?
If the temp I/O is not DIRECT and/or SYNC then seems reasonable that I'd fine most of them in the cache if the cache isn't under pressure.

Anyone look into this?

Thanks
Kyle

On Mon, Aug 26, 2013 at 5:58 AM, Connor McDonald <mcdonald.connor_at_gmail.com>wrote:

> *Does anyone here know what he is talking about?*
> Possibly not your DW architect :-)
>
> Oracle has memory allocations for many things, for temporary workareas, for
> commonly accessed data etc...
>
> So if you've got
>
> a) an abundance of spare RAM floating around, and
> b) evidence that supports you needing more for Oracle activities
>
> you're most probably better off setting the Oracle parameters to consume
> that RAM rather than something such as ram disk etc...
>
> hth
> Connor
>
>
>
>
> On Wed, Aug 21, 2013 at 6:05 AM, Josh Collier <Josh.Collier_at_banfield.net
> >wrote:
>
> > My dw architect recently suggested that I create a tempFS "ramdisk" to
> > increase performance. Honestly I have no idea what he is talking about.
> I
> > am not sure he does either. When googling I am getting information that
> > just confuses me. Does anyone here know what he is talking about?
> > Oracle 11.2.02
> > Redhat 5.4 64bit
> > 500gb ram
> >
> >
> > Creating a disk allocation to use as RAM? That sounds like swap to me.
> >
> > Creating a ram allocation to use as disk, that sounds volatile to me.
> >
> > If am not making any sense, please ignore :)
> >
> >
> >
> > Have a good day.
> >
> > --
> > http://www.freelists.org/webpage/oracle-l
> >
> >
> >
>
>
> --
> Connor McDonald
> ===========================
> blog: connormcdonald.wordpress.com
> web: http://www.oracledba.co.uk
>
> "If you are not living on the edge, you are taking up too much room."
> - Jayne Howard
>
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

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Received on Tue Aug 27 2013 - 22:22:21 CEST