On Mon, Jun 19, 2006 at 02:18:12PM -0400, Sinha_Himanshu@xxxxxxx wrote: > We are running a benchmark that does single threaded 512 KB writes to a > LUN on a CLARiiON storage array. The dual Xeon host (Dell 2650) with 4 > GB of memory runs RHEL 4U3 > > We measured the write bandwidth for writes to the block device > corresponding to the lun (e.g. /dev/sdb), a file in an ext2 filesystem > and to a file in an ext3 file system. > Write b/w for 512 KB writes > Block device 312 MBps > Ext2 file 247 MBps > Ext3 file 130 MBps > > We are looking for ways to improve the ext3 file write bandwidth. > > Tracing of I/Os at the storage array shows that in the case of ext3 > experiment, the workload does not keep the lun busy enough. Every 5 > seconds there is an increase in I/O activity that lasts for 2-3 seconds. > The lun then has very low activity for 2-3 seconds. It appears that the > buffers at the host are flushed every 5 seconds and the flushing takes > 2-3 seconds. To maximize write bandwidth, we would like to be in a > situation where the buffers are flushed continuously to keep the lun > constanly busy. > That is what we see in the case of the ext2 file. > > In the case of ext2 we also see the host do quite a few ver large writes > (up to 7784 KB). Hmm, is the new kernel 2.6.17 addressing such issues? I understand that the new multibuffered implementation of ext3 may enhance the performance considerably. What kernel did you benchmark on? best regards keld _______________________________________________ Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
