On Tue, 2018-04-10 at 23:43 +0200, Uwe Falke wrote: > Hi Aaron, > to how many different files do these tiny I/O requests go? > > Mind that the write aggregates the I/O over a limited time (5 secs or > so) and ***per file***. > It is for that matter a large difference to write small chunks all to > one > file or to a large number of individual files . > to fill a 1 MiB buffer you need about 13100 chunks of 80Bytes > ***per > file*** within those 5 secs. >
Something else to bear in mind is that you might be using a library that converts everything into putchar's. I have seen this in the past with Office on a Mac platform and made performance saving a file over SMB/NFS appalling. I mean really really bad, a "save as" which didn't do that would take a second or two, a save would take like 15 minutes. To the local disk it was just fine. The GPFS angle is this was all on a self rolled clustered Samba GPFS setup back in the day. Took a long time to track down, and performance turned out to be just as appalling with a real Windows file server. JAB. -- Jonathan A. Buzzard Tel: +44141-5483420 HPC System Administrator, ARCHIE-WeSt. University of Strathclyde, John Anderson Building, Glasgow. G4 0NG _______________________________________________ gpfsug-discuss mailing list gpfsug-discuss at spectrumscale.org http://gpfsug.org/mailman/listinfo/gpfsug-discuss