I experienced some embarrassingly bad performance today from a two-node
AFR used by two clients to store and share PHP sessions. (I ended up
switching to NFS by the end of the day.) It was on average a few
thousand sessions with a good smattering of create/write/read with
pretty high concurrency due to some thousands of hits per minute.
I played with settings galore from threading to caching to writeback
caching to client io threads and got about nowhere. The symptoms are
extremely latent i/o requests and high client-side CPU usage but little
if any server-side usage and no actual disk i/o to speak of.
All four nodes are virtualized RHEL 5 instances connected over Gbit.
The last-used configs are below. Any ideas?
Server:
volume php-sessions
type storage/posix
option directory /var/glusterfs/php-sessions
end-volume
volume php-sessions-locks
type features/locks
option mandatory-locks on
subvolumes php-sessions
end-volume
volume php-sessions-brick
type performance/io-threads
option thread-count 16 # default is 16
subvolumes php-sessions-locks
end-volume
volume server
type protocol/server
option transport-type tcp
option transport.socket.nodelay on
option auth.addr.php-sessions-brick.allow 1.2.3.4,1.2.3.5
option listen-port 6996
subvolumes php-sessions-brick
end-volume
Client:
volume gluster0
type protocol/client
option transport-type tcp
option remote-host gluster0
option remote-port 6996
option transport.socket.nodelay on
option remote-subvolume php-sessions-brick
end-volume
volume gluster1
type protocol/client
option transport-type tcp
option remote-host gluster1
option remote-port 6996
option transport.socket.nodelay on
option remote-subvolume php-sessions-brick
end-volume
volume mirror-0
type cluster/replicate
subvolumes gluster0 gluster1
end-volume
volume writeback
type performance/write-behind
option window-size 1MB
subvolumes mirror-0
end-volume
volume io-cache
type performance/io-cache
option cache-size 512MB
subvolumes writeback
end-volume
volume iothreads
type performance/io-threads
option thread-count 4 # default is 16
subvolumes io-cache
end-volume
TIA,
John
--
John Madden
Sr UNIX Systems Engineer
Ivy Tech Community College of Indiana
jmad...@ivytech.edu
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