[Linux-cluster] Block Size

[Jeremy Eder]

I think he's talking about the partition offset rather than filesystem block size...check this:
http://www.vmware.com/pdf/esx3_partition_align.pdf

I agree, using gfs2 in a single node is just fine - when you create the partition, use lock_nolock.





Best Regards,

Jeremy Eder, RHCE, VCP



-----Original Message-----
From: linux-cluster-bounces at redhat.com [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Stephen Nelson-Smith
Sent: Thursday, February 19, 2009 15:35 PM
To: linux clustering
Subject: [Linux-cluster] Block Size

Hi,

I have a 1TB LUN on an EMC SAN, which I see in /proc/partitions as emcpowera.

Ultimately I will be sharing this between two, or three machines, but
at present only one is fibre attached.

I propose to create a GFS2 filesystem now, and use it with one machine
until it becomes necessary to share the LUN with the other machines.

The backups/storage engineer from my hostco recommends I use a
blocksize of 128kb to ensure there are no missed alignments on the SAN
that could degrade performance.  128kb sounds *huge* given that the
default is 4k.

Two questions:

Any problems with the recommended approach - ie mkfs.gfs2 first, worry
about clustering later?

Is mkfs.gfs2 -b 131072 really sane?

Thanks,

S.

-- 
Stephen Nelson-Smith
Technical Director
Atalanta Systems Ltd
www.atalanta-systems.com

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