Hi all, the last few days I've been looking at a problem [1] where a client locks a file over a FUSE-mount, and a 2nd client tries to grab that lock too. It is expected that the 2nd client gets blocked until the 1st client releases the lock. This all work as long as the 1st client cleanly releases the lock. Whenever the 1st client crashes (like a kernel panic) or the network is split and the 1st client is unreachable, the 2nd client may not get the lock until the bricks detect that the connection to the 1st client is dead. If there are pending Replies, the bricks may need 15-20 minutes until the re-transmissions of the replies have timed-out. The current default of 15-20 minutes is quite long for a fail-over scenario. Relatively recently [2], the Linux kernel got a TCP_USER_TIMEOUT socket option (similar to TCP_KEEPALIVE). This option can be used to configure a per-socket timeout, instead of a system-wide configuration through the net.ipv4.tcp_retries2 sysctl. The default network.ping-timeout is set to 42 seconds. I'd like to propose a network.tcp-timeout option that can be set per volume. This option should then set TCP_USER_TIMEOUT for the socket, which causes re-transmission failures to be fatal after the timeout has passed. Now the remaining question, what shall be the default timeout in seconds for this new network.tcp-timeout option? I'm currently thinking of making it high enough (like 5 minutes) to prevent false positives. Thoughts and comments welcome, Niels 1 https://bugzilla.redhat.com/show_bug.cgi?id=1099460 2 http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=dca43c7 _______________________________________________ Gluster-devel mailing list Gluster-devel@xxxxxxxxxxx http://supercolony.gluster.org/mailman/listinfo/gluster-devel
