[PVFS-users] Scaling problems with PVFS 1.6.2

[Nathan Poznick]

Thus spake Kent F. Milfeld:
>   Up to 128 clients, all seems to go well for a simple write
>   of 64MB from each client using MPI-I/O.  However, when 
>   writing from 256 clients, some processes have a write error of 
>   8288 and the processes generally hang.  The processes that show

It sounds like you may be running into a limit in the number of
connections that the manager / iods can accept at any given time.
Testing out whether or not this is the case should be fairly simple.
In include/pvfs_config.h, look for the #defines for MGR_BACKLOG and
IOD_BACKLOG.  They are both currently set to 256 - try bumping them up
significantly and recompile PVFS.  If that fixes your problem, you may
want to consider bumping them up higher based on the maximum number of
clients you expect to use.

-- 
Nathan Poznick <poznick at conwaycorp.net>

We had better appear what we are, than affect to appear what we are
not. - Francois de La Rochefoucauld

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