On Wed, Jul 11, 2007 at 01:46:57AM +0200, Pavel Stano wrote: > Hello, > > i am testing gfs and its very slow, please look at this if it is normal > or i miss something > > i have 2 node cluster, nodes are connected via SAS to disk array promise > e310s, when i run dd on attached block device i have cca 150MBps > throughput on both nodes > there is debian etch, i compile cluster-2.00.00 with gfs1 module > i create one 475GB logical volume (i dont use clvmd, just normal lvm), > create gfs1 on it > gfs_mkfs -t cluster1:data0 -p lock_dlm -j 2 /dev/vgdata0/lvdata0 > mount that lv on both nodes to directory /d/0/, run df on both nodes > and then run touch on node 1: > serpico# touch /d/0/test > > and ls on node 2: > dinorscio:~# time ls /d/0/ > test > > real 0m9.486s > user 0m0.000s > sys 0m0.004s > > it took almost 10 seconds to display 1 file on that filesystem > when i again create other file via touch(node1) and run ls (node2) it > took again cca 10 seconds > i monitor activity with dstat and there is 50% iowait on node where run > ls (50% because 2 core cpu on node), but no disk activity > nodes are connected via 1gbps idle ethernet > > and when ls is runing, i look at wchan with ps > ps axf -o pid,wchan:20,cmd|grep ls > 6387 sync_buffer \_ ls --color=auto /d/0/ > i run ps many times there is still sync_buffer, i dont see other kernel > function Have you found the problem here? 10 seconds definately means something has gone very wrong somewhere. I don't think it's in the dlm or gfs, though. My guess is that the problem is in the i/o layer (sync_buffer is waiting for a write to complete). Could you partition your disk, create an ext3 fs on each partition, have each node mount one of the ext3's, and run some tests? Dave -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
