Trung, what kind of files are you copying? Big ones or small ones? And, how are you copying them? In parallel or one at a time? I'm asking this because the write-behind translator will wait some time before writing. You should have won a lot if there were a lot of parallel writing happening because it would join the requests into fewer packets, meaning: lower packets overhead. Another case where write-behind is very good: some software calls a lot of write operations with tiny data (10 bytes?). In this case, without the write-behind, you would have thousands of packets with 10 bytes of data. But, if you activate it, those thousands will turn into a few bigger packets. Still, if the files you're copying are not small, you should be getting at least something near the speed without write-behind because the cache is getting full every time. I'm not a GlusterFS developer, so please anyone correct where I'm wrong. I really want to learn to think exactly as GlusterFS thinks. Best regards, Daniel Colchete On 6/12/07, Trung Le Thanh <trung_bmt@xxxxxxxxx> wrote:
Hi all, I have a glusterfs setup with 4 servers connected by a 100Mbps switch. The configuration files are exactly like those on wiki. And I experienced a very strange issue. With write-back is enabled, the speed of copying file from local hdd on a client to glusterfs is much slower when write-back is disabled. I tried with many different values of aggregate size (4KB -> 2MB) and the result is still the same. I think that the write-back is supposed to boost performance dramatically in this case. One more issue is when there is: when I copy a directory to glusterfs, the speed is around 1.5MB/s. When I start to copy another similar directory to glusterfs, the speed drops to less than 1MB/s. I supposed to saw the speed of 3MB/s. Currently I have the content of /etc/sysctl.conf like this: net.core.somaxconn = 1024 net.core.netdev_max_backlog = 2500 net.ipv4.tcp_max_syn_backlog = 1024 net.ipv4.tcp_congestion_control = bic net.ipv4.ip_local_port_range = 1024 65000 fs.file_max = 64000 net.ipv4.tcp_keepalive_time = 3600 net.ipv4.tcp_tw_reuse = 1 net.ipv4.tcp_tw_recycle = 1 net.ipv4.tcp_rfc1337 = 1 net.ipv4.tcp_no_metrics_save = 1 net.ipv4.tcp_timestamps = 0 net.ipv4.tcp_fin_timeout = 30 net.core.rmem_max = 16777216 net.core.wmem_max = 16777216 net.ipv4.tcp_rmem = 4096 87380 16777216 net.ipv4.tcp_wmem = 4096 65536 16777216 net.ipv4.conf.default.rp_filter = 1 net.ipv4.tcp_syncookies = 1 net.ipv4.tcp_synack_retries = 3 net.ipv4.tcp_syn_retries = 3 I don't know where the problem is and I really appreciate any help from you Thank you very much Best regards, Trung _______________________________________________ Gluster-devel mailing list Gluster-devel@xxxxxxxxxx http://lists.nongnu.org/mailman/listinfo/gluster-devel
