[CentOS] adding SAN "diskspace" to CentOS system residing on VMware

Ross Walker rswwalker at gmail.com
Tue Nov 3 03:17:09 UTC 2009


On Nov 2, 2009, at 10:15 AM, "Flaherty, Patrick" <pflaherty at wsi.com>  
wrote:

> If you are a good little doobie, check with your san admin to see if  
> you
> need to change your starting block alignment. If he looks at you  
> funny,
> take everything the man says to you with a grain of salt for the  
> rest of
> your life.
>
> http://www.vmware.com/pdf/esx3_partition_align.pdf

Always hedge your bet and start your partitions at 1MB offset, that  
should cover most chunk sizes.

With LVM make sure you build into the PVs the offset. I believe the  
metadata is 128K and the first LV is an additional 64K offset, making  
the data start at 192K. Fine if your stripe chunk size is 64K, but to  
cover all the possible chunk sizes make the metadata size 1MB minus  
64K during pvcreate. I also set metadatacopies to 2 so there is a  
backup.

-Ross



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