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Patrick Hunt commented on ZOOKEEPER-885: ---------------------------------------- Alexandre, Can you provide some additional detail: 1) you are applying the load using dd to all three servers at the same time, is that correct? (not just to 1 server) 2) /dev/mapper indicates some sort of lvm setup, can you give more detail on that? (fyi http://ubuntuforums.org/showthread.php?t=646340) 3) you mentioned that this: {quote} echo 5 > /proc/sys/vm/dirty_ratio echo 5 > /proc/sys/vm/dirty_background_ratio {quote} resulting in "stability in this test", can you tell us what this was set to initially? > Zookeeper drops connections under moderate IO load > -------------------------------------------------- > > Key: ZOOKEEPER-885 > URL: https://issues.apache.org/jira/browse/ZOOKEEPER-885 > Project: Zookeeper > Issue Type: Bug > Components: server > Affects Versions: 3.2.2, 3.3.1 > Environment: Debian (Lenny) > 1Gb RAM > swap disabled > 100Mb heap for zookeeper > Reporter: Alexandre Hardy > Priority: Critical > Attachments: tracezklogs.tar.gz, tracezklogs.tar.gz, > WatcherTest.java, zklogs.tar.gz > > > A zookeeper server under minimum load, with a number of clients watching > exactly one node will fail to maintain the connection when the machine is > subjected to moderate IO load. > In a specific test example we had three zookeeper servers running on > dedicated machines with 45 clients connected, watching exactly one node. The > clients would disconnect after moderate load was added to each of the > zookeeper servers with the command: > {noformat} > dd if=/dev/urandom of=/dev/mapper/nimbula-test > {noformat} > The {{dd}} command transferred data at a rate of about 4Mb/s. > The same thing happens with > {noformat} > dd if=/dev/zero of=/dev/mapper/nimbula-test > {noformat} > It seems strange that such a moderate load should cause instability in the > connection. > Very few other processes were running, the machines were setup to test the > connection instability we have experienced. Clients performed no other read > or mutation operations. > Although the documents state that minimal competing IO load should present on > the zookeeper server, it seems reasonable that moderate IO should not cause > problems in this case. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.