>From what I can see in the source code, the default is actually even lower at 100 ms (can be overridden with hbase.regionserver.hlog.slowsync.ms).
---- Saad On Tue, Apr 26, 2016 at 3:13 AM, Kevin Bowling <[email protected]> wrote: > I see similar log spam while system has reasonable performance. Was the > 250ms default chosen with SSDs and 10ge in mind or something? I guess I'm > surprised a sync write several times through JVMs to 2 remote datanodes > would be expected to consistently happen that fast. > > Regards, > > On Mon, Apr 25, 2016 at 12:18 PM, Saad Mufti <[email protected]> wrote: > > > Hi, > > > > In our large HBase cluster based on CDH 5.5 in AWS, we're constantly > seeing > > the following messages in the region server logs: > > > > 2016-04-25 14:02:55,178 INFO > > org.apache.hadoop.hbase.regionserver.wal.FSHLog: Slow sync cost: 258 ms, > > current pipeline: > > [DatanodeInfoWithStorage[10.99.182.165:50010 > > ,DS-281d4c4f-23bd-4541-bedb-946e57a0f0fd,DISK], > > DatanodeInfoWithStorage[10.99.182.236:50010 > > ,DS-f8e7e8c9-6fa0-446d-a6e5-122ab35b6f7c,DISK], > > DatanodeInfoWithStorage[10.99.182.195:50010 > > ,DS-3beae344-5a4a-4759-ad79-a61beabcc09d,DISK]] > > > > > > These happen regularly while HBase appear to be operating normally with > > decent read and write performance. We do have occasional performance > > problems when regions are auto-splitting, and at first I thought this was > > related but now I se it happens all the time. > > > > > > Can someone explain what this means really and should we be concerned? I > > tracked down the source code that outputs it in > > > > > > > hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java > > > > but after going through the code I think I'd need to know much more about > > the code to glean anything from it or the associated JIRA ticket > > https://issues.apache.org/jira/browse/HBASE-11240. > > > > Also, what is this "pipeline" the ticket and code talks about? > > > > Thanks in advance for any information and/or clarification anyone can > > provide. > > > > ---- > > > > Saad > > >
