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
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