[Lustre-discuss] MDT and MGS

[Jeff Darcy]

Brian J. Murrell wrote:
> This is _exactly_ the reason that we recommend a separate MGS for
> installations that have even a notion of wanting more than one
> filesystem.
>   
I just checked, and the current Lustre operations manual (v1.14, updated 
September 19) does not seem to reflect that belief; even the "more 
complex configurations" offer mkfs.lustre commands that give a combined 
MGS/MDT.  In any case, my experience has been that customers are often 
reluctant to carve a whole LUN out of their disk arrays for so little 
data, and partitioning can have undesirable performance impacts.  Has 
any consideration been given to ways of storing the MGS information 
within a file on an existing filesystem instead of requiring on a 
separate block device?  I'm tempted to suggest doing this via the 
loopback driver, since the MGS data-change rate is so low anyway.