> > ctrl-c will not stop the repair. > Ok, so that's why I've been seeing logs of repairs on other CFs
That's probably the 2280 issue. Data from all CF's is streamed over > Ah, I get it now. Thanks > > Cheers > > ----------------- > Aaron Morton > Freelance Cassandra Developer > @aaronmorton > http://www.thelastpickle.com > > On 17/08/2011, at 10:09 AM, Philippe wrote: > > One last thought : what happens when you ctrl-c a nodetool repair ? Does it > stop the repair on the server ? If not, then I think I have multiple repairs > still running. Is there any way to check this ? > > Thanks > > 2011/8/16 Philippe <watche...@gmail.com> > >> Even more interesting behavior : a repair on a CF has consequences on >> other CFs. I didn't expect that. >> >> There are no writes being issued to the cluster yet the logs indicate >> that >> >> - SSTableReader has opened dozens and dozens of files, most of them >> unrelated to the CF being repaired >> - compactions are taking place continuously on CFs other than the one >> being repaired, even CFs in other keyspaces >> - I see "Sending AEService tree" messages for CF not being repaired. >> >> >> After a very long time, I got some AES messages indicating that streaming >> from node C had finished and then many minutes after that node B. And yet >> the pending stream count on node B hasn't changed. >> >> The *-data.db files for the CF being repaired are about 70MB on-disk. >> >> Maybe when a stream is fully received on node B, netstats indicates that >> no streams are pending but since they are not acknowledged, node A doesn't ? >> >> >> 2011/8/16 Philippe <watche...@gmail.com> >> >>> I'm still trying different stuff. Here are my latest findings, maybe >>> someone will find them useful: >>> >>> - I have been able to repair some small column families by issuing a >>> repair [KS] [CF]. When testing on the ring with no writes at all, it >>> still >>> takes about 2 repairs to get "consistent" logs for all AES requests. >>> - Launching a repair one the smallest CF of the biggest KS has >>> triggered a flurry of compactions and streams. Some of those streams are >>> for >>> other CF in that keyspace !? >>> - During repairs (one at a time cluster-wide), I get 25-50% io waits >>> & 35%-50% cpu usage on a 6 core SATA-disk setup >>> >>> What is surprising to me (bug?) is that netstats shows me streams going >>> from node A to node B at 0% progress. But netstats on node B doesn't show me >>> any streams coming in. I'm thinking that repairs may be never ending and >>> that may be messing up my compactions hence the huge pile up of compactions >>> until the disk fulls. >>> I know there's an issue related to failed streams & repairs, could I be >>> hitting it ? >>> >>> Thanks >>> >>> 2011/8/14 Philippe <watche...@gmail.com> >>> >>>> @Teijo : thanks for the procedure, I hope I won't have to do that >>>> >>>> Peter, I'll answer inline. Thanks for the detailed answer. >>>> >>>> >>>>> > the number of SSTables for some keyspaces goes dramatically up (from >>>>> 3 or 4 >>>>> > to several dozens). >>>>> >>>>> Typically with a long running compaction, such as that triggered by >>>>> repair, that's what happens as flushed memtables accumulate. In >>>>> particular for memtables with frequent flushes. >>>>> >>>>> Are you running with concurrent compaction enabled? >>>>> >>>> Yes, it is enabled. On my 0.8 cluster, cassandra.yaml has this (it's >>>> commented). BTW, I have 6 cores on each server. >>>> #concurrent_compactors: 1 >>>> >>>> > the commit log keeps increasing in size, I'm at 4.3G now, it went up >>>>> to 40G >>>>> > when the compaction was throttled at 16MB/s. On the other nodes it's >>>>> around >>>>> > 1GB at most >>>>> Hmmmm. The Commit Log should not be retained longer than what is >>>>> required for memtables to be flushed. Is it possible you have had an >>>>> out-of-disk condition and flushing has stalled? Are you seeing flushes >>>>> happening in the log? >>>>> >>>> No I don't believe there was ever an out of disk. Yes it is flushing >>>> for the first couple of hours. >>>> Then, when repair seems locked up, my log is mostly filled with lines >>>> such as this >>>> INFO [ScheduledTasks:1] 2011-08-14 23:15:47,267 StatusLogger.java (line >>>> 88) [My_Keyspace].[My_Columnfamily] 45,105541 50/50 >>>> 20/20 >>>> Why is that ? >>>> >>>> > the data directory is bigger than on the other nodes. I've seen it go >>>>> up to >>>>> > 480GB when the compaction was throttled at 16MB/s >>>>> How much data are you writing? Is it at all plausible that the huge >>>>> spike is a reflection of lots of overwriting writes that aren't being >>>>> compacted? >>>>> >>>> No, there's no bulk loading going on at the moment and I'm pretty sure >>>> there wasn't when it spiked up to that load. >>>> I've never measured the load because it's a mix of counter increments >>>> and new counters all the time. It's not that much though. >>>> >>>> >>>>> Normally when disk space spikes with repair it's due to other nodes >>>>> streaming huge amounts (maybe all of their data) to the node, leading >>>>> to a temporary spike. But if your "real" size is expected to be 60, >>>>> 480 sounds excessive. Are you sure other nodes aren't running repairs >>>>> at the same time and magnifying each other's data load spikes? >>>>> >>>> Yes, the two other nodes were running repairs. I had them scheduled at 8 >>>> hour intervals but they must have started. >>>> When data is streamed from one to another, does that data go into the >>>> commit log as a regular write ? >>>> How much of a negative impact can that have on the repair going on on >>>> this node ? >>>> >>>> > What's even weirder is that currently I have 9 compactions running but >>>>> CPU >>>>> > is throttled at 1/number of cores half the time (while > 80% the rest >>>>> of the >>>>> > time). Could this be because other repairs are happening in the ring >>>>> ? >>>>> You mean compaction is taking less CPU than it "should"? >>>>> >>>> Yes >>>> >>>> >>>>> No, this should not be due to other nodes repairing. However it sounds >>>>> to me like you are bottlenecking on I/O and the repairs and >>>>> >>>> Yes, I/O is really high on the node right now. Around 50% I/O waits. >>>> >>>> >>>>> compactions are probably proceeding extremely slowly, probably being >>>>> completely drowned out by live traffic (which is probably having an >>>>> abnormally high performance impact due to data size spike). >>>>> >>>> Yes, the live traffic is 3 to 10x times slower during repair. Ouch... I >>>> hope I won't to do this too often while in production ! >>>> >>>> >>>>> >>>>> What's your read concurrency configured on the node? What does "iostat >>>>> -x -k 1" show in the average queue size column? >>>> >>>> Average queue size on the disk (RAID-1 + separate LVM volumes for data, >>>> commit log, caches, logs)) varies between 2 and 90. I'd say the average is >>>> around 30-40. Very high variation. >>>> >>>> >>>>> Is "nodetool -h >>>>> localhost tpstats" showing that ReadStage is usually "full" (@ your >>>>> limit)? >>>>> >>>> No backlog at all in tpstats >>>> >>>> I've figured out how AES is logging its actions and it looks like it >>>> really is going through every CF in every keyspace and doing a tree request >>>> for every token range >>>> So it really looks like it's just taking forever to compact stuff as >>>> it's repairing. >>>> I saw in another email that repairing was taking 2-3mn/ GB... it looks >>>> like a lot more for my ring. Anybody else have numbers ? >>>> >>>> Thanks >>>> >>> >>> >> > >
