Re: ASM and disk partitions offset
- From: Niall Litchfield <niall.litchfield@xxxxxxxxx>
- To: cichomitiko@xxxxxxxxx
- Date: Thu, 16 Feb 2012 10:34:08 +0000
Dimitre,
"I wouldn't bother" is probably incorrect. The details will depend on the
array stripe size, the sector sizes and probably the specific hardware.
That said most vendors recommend the 1mb starting point for a partition
because it has as a common divisor most of the usual allocation unit sizes
and disk label sizes. I quite like this article
http://blogs.msdn.com/b/jimmymay/archive/2009/05/08/disk-partition-alignment-sector-alignment-make-the-case-with-this-template.aspx
written from a windows perspective with SQL in mind, but really the basic
issue isn't software specific. FWIW Oracle, Microsoft and VMWare all
recommend that you align your storage hardware with the FS/Volume manager
so as to avoid doing multiple IO requests where a single request would do,
references below.
http://www.vmware.com/pdf/Perf_Best_Practices_vSphere4.0.pdf
http://www.oracle.com/technetwork/articles/systems-hardware-architecture/lun-alignment-163801.pdf
http://support.microsoft.com/kb/929491
On Thu, Feb 16, 2012 at 10:12 AM, Radoulov, Dimitre
<cichomitiko@xxxxxxxxx>wrote:
> On Thu, Feb 16, 2012 at 7:29 AM, Stalin Subbiah <stalinsk@xxxxxxxxx>
> wrote:
> > I believe it was also done to align ASM disks with stripe size which is
> generally in multiples of 2. At least this was the case with Linux, using
> fdisk for disk partitions.
>
> Thanks Stalin,
> but what that means: that a partition beginning at the first cylinder
> is not aligned with the HW stripe size (presumably a power of 2)?
>
> I've asked if the storage team had some special requirement (or
> suggestion) as far as the first cylinder of the partitions is
> concerned and I've received a generic reply that I shouldn't bother.
>
>
> Best regards
> Dimitre
>
>
> > On Feb 13, 2012, at 3:13 PM, "Radoulov, Dimitre" <cichomitiko@xxxxxxxxx>
> wrote:
> >
> >> I meant:
> >>
> >> now I remember that once, when I was setting up a test RAC on Solaris, I
> >> wasn't able to make the partitions visible for asm disk creation
> >> [...]
> >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >>
> --
> //www.freelists.org/webpage/oracle-l
>
>
>
--
Niall Litchfield
Oracle DBA
http://www.orawin.info
--
//www.freelists.org/webpage/oracle-l
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