[Pvfs2-users] pvfs2 performance with btio

[Florin Isaila]

Hi everybody,

I have a question about the PVFS2 write performance.

We did some measurements with BTIO over PVFS2 on lonestar at TACC
(http://www.tacc.utexas.edu/services/userguides/lonestar/)

and we get pretty bad write results with classes B and C:

http://www.arcos.inf.uc3m.es/~florin/btio.htm

We used 16 I/O servers, the default configuration parameters and upto
100 processes. We realized that all I/O servers were used also as
metadata servers, but BTIO uses just one file.

The times are in seconds, contain only I/O time (no compute time) and
are aggregated per each BTIO run (BTIO performs several writes).

TroveSyncMeta was set to yes (by default). Could this cause the I/O to
be serialized? It looks as if there were a serialization.

Or could the fact that all nodes were also launched as metadata
managers affect the performance?

Any clue why this happens?

Many thanks
Florin