[Linux-cluster] Block Size

[Steven Whitehouse]

Hi,

On Thu, 2009-02-19 at 20:35 +0000, Stephen Nelson-Smith wrote:
> 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.
> 
Block size is limited by page size, so 4k is as big as you can have I'm
afraid,

Steve.