[Linux-cluster] GFS performance

[Ferenc Wagner]

Kamal Jain <kjain at aurarianetworks.com> writes:

> I am surprised that handling locking for 8 files might cause major
> performance degradation with GFS versus iSCSI-direct.
>
> As for latency, all the devices are directly connected to a Cisco
> 3560G switch and on the same VLAN, so I expect Ethernet/layer-2
> latencies to be sub-millisecond.  Also, note that the much faster
> iSCSI performance was on the same GbE connections between the same
> devices and systems, so network throughput and latency are the same.
>
> GFS overhead, in handling locking (most likely) and any GFS
> filesystem overhead are the likely causes IMO.
>
> Looking forward to any analysis and guidance you may be able to
> provide on getting GFS performance closer to iSCSI-direct.

I'm really interested in the outcome of this discussion.  Meanwhile I
can add that 'gfs_controld -l0' and 'gfs_tool settune /mnt demote_secs 600'
(as recommended on this list by the kind developers) helped me
tremendously dealing with lots of files.
-- 
Regards,
Feri.