Lustre discuss - Nov 2009 - Size of MGT?

Dear List

In the case where a the MDS and MGS are configured separately, what size
does the MGT have to be?  Reason would suggest it could be quite small, say
32MB.  What would be a sensible minimum? Are there factors which would
indicate a move away from the minimum? For example if it is planned to
configure 2000 lustre filesystems, or the filesystem will consists of 20 000
servers.

In short, are there guidelines for suggesting MGT size?

Regards

Geoff Carrier
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On 2009-11-17, at 01:46, Geoff Lustre wrote:
> In the case where a the MDS and MGS are configured separately, what  
> size does the MGT have to be?  Reason would suggest it could be  
> quite small, say 32MB.  What would be a sensible minimum? Are there  
> factors which would indicate a move away from the minimum? For  
> example if it is planned to configure 2000 lustre filesystems, or  
> the filesystem will consists of 20 000 servers.
>
> In short, are there guidelines for suggesting MGT size?

Please search the recent list archives for a discussion of this.

AFAIR, ORNL has an MGT data of about 128MB, but that is the largest
filesystem in the world.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.