On Mon, Jul 19, 2010 at 11:41:07AM -0400, Fred Wittekind wrote:
Two web servers, both virtualized with CentOS Xen servers as host (residing on two different physical servers). GFS used to store home directories containing web document roots.
Shared block device used by GFS is an ISCSI target with the ISCSI initiator residing on the Dom-0, and presented to Dom-U webservers as drives. Also, providing a second shared block device for quorum disk.
If I hit the web site on just one of the nodes, it behaves as expected. If I try to load the websites from both nodes at the same time (two web browser instances), the load average on both nodes spikes, and page loads very slowly. The site I am trying to host is very high traffic, and if the servers can be nearly brought to there knees with two web browser instances running on a single workstation, that's not going to work.
I am not seeing any error messages in the logs regarding the cluster.
Any help or suggestions on how to troubleshoot this issue would be greatly appreciated.
You might want to read linux-cluster mailinglist archives for GFS performance tuning tips.
Make sure you modify (increase) at least the max lock rate.
-- Pasi
[root@www3 www]# find ./ | wc -l 64815
[root@www3 www]# gfs2_tool df /home/www /home/www: SB lock proto = "lock_dlm" SB lock table = "Web:homewww" SB ondisk format = 1801 SB multihost format = 1900 Block size = 4096 Journals = 2 Resource Groups = 316 Mounted lock proto = "lock_dlm" Mounted lock table = "Web:homewww" Mounted host data = "jid=1:id=393217:first=0" Journal number = 1 Lock module flags = 0 Local flocks = FALSE Local caching = FALSE
Type Total Blocks Used Blocks Free Blocks use%
data 20707148 4347237 16359911 21% inodes 16426386 66475 16359911 0%
[root@www3 www]# gfs2_tool gettune /home/www new_files_directio = 0 new_files_jdata = 0 quota_scale = 1.0000 (1, 1) logd_secs = 1 recoverd_secs = 60 statfs_quantum = 30 stall_secs = 600 quota_cache_secs = 300 quota_simul_sync = 64 statfs_slow = 0 complain_secs = 10 max_readahead = 262144 quota_quantum = 60 quota_warn_period = 10 jindex_refresh_secs = 60 log_flush_secs = 60 incore_log_blocks = 1024
[root@www3 www]# cat /etc/cluster/cluster.conf |egrep '(dlm)|(gfs)' <dlm plock_ownership="1" plock_rate_limit="0"/> <gfs_controld plock_rate_limit="0"/>
Fred Wittekind _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos