Hi, We did some GFS benchmarking using an application that writes many small files. There seems to be a big overhead (in the amount of actual data written to the device) with these small files. Info: - Mount options: noatime,lockproto=lock_nolock - GFS version: 20050506 of RHEL4 branch - Number of files written: 10000 File size | block write speed | fs write speed ---------------------------------------------- 10k | 13-14 MB/s | 2.2 MB/s 50k | 18-19 MB/s | 8.3 MB/s 100k | 21-22 MB/s | 13.5 MB/s - "fs write speed" is the write speed as seen by the application - "block write speed" is the write speed to the underlying block device, as reposted by iostat (and verified with the raid controller's monitoring utility). So from this it seems that GFS is writing ~50k "extra data" for each file through the block device. Note: this "extra data" is not taken away from the free disk space as reposted by df. Any ideas why this is happening? Any ideas of parameters that could be tuned? ( ext3 on the same block device does not have this issue.) Thanks, - Alexander -- Linux-cluster@xxxxxxxxxx http://www.redhat.com/mailman/listinfo/linux-cluster
