[Linux-cluster] GFS performance
Ferenc Wagner
wferi at niif.hu
Fri Jan 4 15:06:17 UTC 2008
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.
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