Re: Optimal hard disk layout for Oracle

Hi !

Basically 'forcedirectio' bypasses the OS buffer cache and talks directly to the disk. This increases the performance since there is no 'middle man' during the IO.

This is HIGHLY recommended for redo logs. In this case the OS buffer cahce is bypassed.

Regards,
K Gopalakrishnan
Bangalore, INDIA

• Original Message ----- From: VIVEK_SHARMA <VIVEK_SHARMA_at_infy.com> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> Sent: Monday, September 04, 2000 8:32 AM Subject: RE: Optimal hard disk layout for Oracle

Pedro wrote - "Use forcedirectio on Oracle database devices" Give more Detail please on forcedirectio . Novice on O.S. here

> -----Original Message-----
> From: Figueiredo, Pedro [SMTP:PFigueiredo_at_europeantelecom.at]
> Sent: Saturday, September 02, 2000 8:05 AM
> To: Multiple recipients of list ORACLE-L
> Subject: RE: Optimal hard disk layout for Oracle
>
> Hi,
>
> I believe Raid 5 is not very recommended with OLTP environments.
> If you can use Raid 0 + 1 in a cluster solution it would be the ideal
> solution.
> Do some more research on the subject...
>
> If you have the possibility, use raw devices (at least) for the redo log
> files.
> Use forcedirectio on Oracle database devices (Sun Solaris terminology,
> other
> platforms should have similar possibility). No need to have both Oracle
> and
> OS buffering disk writes...
>
> Best regards
>
> Pedro Figueiredo
>
> -----Original Message-----
> Sent: sábado, 2 de Setembro de 2000 1:50
> To: Multiple recipients of list ORACLE-L
>
>
> Hi,
> Since Temp and Rollbacks are almost all writes you may want to put them on
> a
> mirror set rather than Raid 5. There is a bit of a write penalty but not
> a
> major one.
>
> _Ernie
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Friday, September 01, 2000 6:08 PM
>
>
> > Hi!
> >
> > We are about to get a new database server and my supervisor wants me to
> > specify the hard disk layout. It is a given that we wanna go with RAID
> 5.
> So
> > here is what I'm thinking about:
> >
> > Disk 1: Operating system + Oracle software
> > Disk 2: Online Redo Logs
> > Disk 3: Online Redo logs (mirrored)
> > Disk 4: archived redo logs
> > Disk 5-8: Oracle data files (i.e data + index tablespaces, temp
> tablespaces,
> > rollback segments)
> >
> > Disks 1-4 will be 'stand-alone' disks (i.e. no RAID or mirroring). Disks
> 5-8
> > will be in a RAID 5 array.
> >
> > Do you think it would be beneficial to add like another disk (e.g. place
> > rollback segments or temp tablespace on a separate disk)?
> >
> > Any input would be appreciated.
> >
> > Thanks,
> > Helmut
> >
> > --
> > Author: Helmut Daiminger
> > INET: hdaiminger_at_vivonet.com
> >
> > Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
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> --
> Author: Ernest Simard
> INET: simard_at_sonoma.edu
>
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> --
> Author: Figueiredo, Pedro
> INET: PFigueiredo_at_europeantelecom.at
>
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--
Author: VIVEK_SHARMA
  INET: VIVEK_SHARMA_at_infy.com

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