Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Sat, May 2, 2009 at 2:06 PM, Lars Ellenberg <lars.ellenberg at linbit.com>wrote: > nice. you are going into page cache here, mostly > (how much RAM did you say you have?) > 4GB on one node, 8GB on the other. I verified that benchmark numbers are the same on both nodes. > dd if=/dev/zero of=/dev/drbd0 bs=4M count=1000 oflag=direct > > 4194304000 bytes (4.2 GB) copied, 17.6633 seconds, 237 MB/s > > do variations. > use 512k, 1M, 2M, 100M. > After rerunning these various sizes, there is no appreciable performance difference from bs=4M, in either connected or disconnected mode, across all flags. I didn't do connected benchmarks on a single core, as the resync performance dropped by 100MB/s with only one core.. repeat measurements. > see how reproducable they are. Very consistent, with a margin of error of a few megabytes one way or the other; no significant fluctuations. also read up about the "al-extents" drbd.conf parameter, "max-buffers", > and the rest of the usual tuning stuff. the activity log updates will > slow you down on streaming writes. Neither has any noticeable effect (buffered and fsync may actually be a little slower with larger max-buffers), but I am running with the metadata on a ramdisk.. what is your rtt, small packets, large packets? > ping -w 5 -f -s 64 other-node > ping -w 5 -f -s 5000 other-node PING 10.0.0.3 (10.0.0.3) 64(92) bytes of data. . --- 10.0.0.3 ping statistics --- 147010 packets transmitted, 147010 received, 0% packet loss, time 5001ms rtt min/avg/max/mdev = 0.020/0.023/0.153/0.003 ms, ipg/ewma 0.034/0.023 ms PING 10.0.0.3 (10.0.0.3) 5000(5028) bytes of data. --- 10.0.0.3 ping statistics --- 70976 packets transmitted, 70976 received, 0% packet loss, time 5001ms rtt min/avg/max/mdev = 0.043/0.047/0.164/0.009 ms, ipg/ewma 0.070/0.049 ms Hope that helps, -Gennadiy -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20090505/dfc88f25/attachment.htm>