[CentOS] Partition alignment

Rubin rubin at xs4all.nl
Tue Nov 10 08:03:17 UTC 2009


Hi Scott,

Fwiw, I'm doing this for DMX 4 and DMX 5 (vmax) by 128k sectors, as
recommended by EMC in their document "Implementing Virtual Provisioning
On EMC Symmetrix DMX With Oracle 10g & Oracle 11g".

Essentially, the DMX 3 and earlier had a 32kb tracksize (by default,
afaik) which meant that the default partition alignment of 64 sectors on
an mbr partition table were a perfect match. DMX 4 and 5 have a 64kb
tracksize and thus, if you want to minimize hitting physical disk
surfaces, EMC recommends you set this to 128 sectors.

Most of the times though, I think the cache in the diskbox will
alleviate this issue; I suppose it is only an issue on very busy/large
diskboxes.

The document I've mentioned also has automation examples for you that
help setting this up. Don't know about doing this directly from the
partitioning part of kickstart tho..

So, not specific to NetApp, but it might be helpful. Here's a link to
another site which has collected various informations relating to
another (related) matter, namely the LVM side of the story:


http://anosi.blogspot.com/2009/07/lvm-installation-partition-alignment.html

Kind regards,


Rubin.

On 11/09/2009 08:10 PM, nate wrote:
> Scott McClanahan wrote:
>> I'll be setting up a vSphere 4 environment hosting CentOS 5.4 on Netapp
>> FAS and was curious how you guys are handling the automation of
>> partition alignment within your linux guests.  I'd like to use cobbler
>> for dynamically creating kickstart scripts and wasn't sure if I could
>> align my disk during install some how.  Are there kickstart arguments to
>> force the alignment on a 4k boundary?  Have any of you had to do this?
> 
> My storage array abstracts the disks to the point where there is
> no need for alignment(if you wanted to try there's no way you could
> determine how best to do it), and the intelligent caching on the back
> end automatically takes care of doing things like full stripe writes
> and maximizing spindle efficiency -
> 
> http://portal.aphroland.org/~aphro/vv-mgmt.png
> 
> So no I haven't had to do it, and don't plan to in the future.
> 
> nate
> 
> 
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