I hope I'm not hijacking the thread but I'm seeing what I think is a similar issue. About a week ago I loaded a bunch of data into a newly created table. It took about an hour and resulted in 12 regions being created on a single node. (Afterwards I remembered a conversation with JD where he described this behavior and how you could pre-create at least N regions where N is your number of nodes to get better distribution off the bat).
Anyway, it's been about a week and all regions for the table are still on 1 node. I see messages like this in the logs every 5 minutes: 2011-03-14 15:59:03,148 INFO org.apache.hadoop.hbase.master.LoadBalancer: Skipping load balancing. servers=4 regions=62 average=15.5 mostloaded=16 leastloaded=16 It seems the total regions are evenly balanced, but individual tables are not. Where should I look to troubleshoot why this table's regions (as well as others) aren't evenly distributed? I'd guess that I can major compact all tables to fix it, but I'd like to figure out why it hasn't happened automatically. HBase 0.90.0 CDH3b2 thanks, Bill On Mon, Mar 14, 2011 at 3:31 PM, Weiwei Xiong <xion...@gmail.com> wrote: > I see. Thanks Ryan. > > -- Weiwei > > On Mon, Mar 14, 2011 at 3:28 PM, Ryan Rawson <ryano...@gmail.com> wrote: > >> by default runs 1x/day. you can do it manually in the hbase shell by >> typing: >> >> hbase(main):001:0> major_compact "table_name" >> >> -ryan >> >> >> On Mon, Mar 14, 2011 at 3:25 PM, Weiwei Xiong <xion...@gmail.com> wrote: >> > Thanks for your info Ryan. >> > Does HBase do major compaction regularly or do I need to manually do >> this? >> > If it's automatic, how frequently is it performed? >> > I am running 1 replication. >> > Thanks, >> > -- Weiwei >> > >> > On Mon, Mar 14, 2011 at 3:18 PM, Ryan Rawson <ryano...@gmail.com> wrote: >> >> >> >> HDFS does the data rebalancing, over time as major compactions and new >> >> data comes in, files are written first to the local node then to >> >> remote nodes. >> >> >> >> Whats the replication factor you are running? HDFS on 2 nodes is >> >> tricky, since you can either choose r=1 (no data protection) or r=2 >> >> (all writes go to both nodes). >> >> >> >> The sweet spot is above 6 nodes alas. >> >> >> >> -ryan >> >> >> >> On Mon, Mar 14, 2011 at 3:12 PM, Weiwei Xiong <xion...@gmail.com> >> wrote: >> >> > Sorry I forgot to mention. I am using HBase 0.90.1 over HDFS >> 0.20.append >> >> > Thanks, >> >> > -- Weiwei >> >> > >> >> > On Mon, Mar 14, 2011 at 3:10 PM, Weiwei Xiong <xion...@gmail.com> >> wrote: >> >> >> >> >> >> Thanks very much for your replies. >> >> >> Something was unclear in my previous emails. I had one node started >> >> >> first >> >> >> and another was added in later. And there're already some regions >> >> >> created in >> >> >> the first started node. Then I started to import more data into the >> >> >> same >> >> >> table and found that it's always the first node that keeps serving >> the >> >> >> data >> >> >> writes. >> >> >> Actually I was expecting that the region data would be re-balanced to >> >> >> another data node. And I did see in the master log that HBase master >> is >> >> >> trying to unassigning some regions from the overloaded node and >> >> >> re-assign >> >> >> them to the less-loaded node. But the real data was never migrated. >> >> >> I think I observed the region index and cache rebalancing from the >> >> >> master >> >> >> log (correct me if I were wrong). Does anyone know how frequently >> this >> >> >> happens? >> >> >> Another question is, does HBase support data and I/O rebalancing? Or >> I >> >> >> should rely on HDFS to do data rebalancing? I guess HBase should also >> >> >> support data rebalancing otherwise every time I restart HBase the >> >> >> regions >> >> >> will have to be rebalanced again. Will someone tell me how to >> configure >> >> >> or >> >> >> program HBase to do data rebalancing? >> >> >> Thanks, >> >> >> -- Weiwei >> >> >> On Mon, Mar 14, 2011 at 2:43 PM, Ryan Rawson <ryano...@gmail.com> >> >> >> wrote: >> >> >>> >> >> >>> What version of HBase are you testing? >> >> >>> >> >> >>> Is it literally 0 vs N assignments? >> >> >>> >> >> >>> On Mon, Mar 14, 2011 at 1:18 PM, Weiwei Xiong <xion...@gmail.com> >> >> >>> wrote: >> >> >>> > Thanks! >> >> >>> > >> >> >>> > I checked the master log and found some info like this: >> >> >>> > " timestamp ***, INFO org.apache.hadoop.hbase.master.HMaster: >> >> >>> > balance >> >> >>> > hri=***, src=***, dst=*** " >> >> >>> > >> >> >>> > So I assume the balancer is running. There's no failing info >> there, >> >> >>> > but >> >> >>> > I >> >> >>> > didn't see the regions were actually balanced as the log states. >> >> >>> > >> >> >>> > Is it possible that I have been keeping dumping data into the >> table >> >> >>> > thus the >> >> >>> > balancing won't work? >> >> >>> > >> >> >>> > Thanks, >> >> >>> > -- Weiwei >> >> >>> > >> >> >>> > On Mon, Mar 14, 2011 at 12:15 PM, Stack <st...@duboce.net> wrote: >> >> >>> > >> >> >>> >> Check the master log. See if the load balancer is running or >> not. >> >> >>> >> It >> >> >>> >> usually runs every 5 minutes by default. It may not run if >> regions >> >> >>> >> are transitioning. It'll log regardless. >> >> >>> >> >> >> >>> >> St.Ack >> >> >>> >> >> >> >>> >> On Mon, Mar 14, 2011 at 10:50 AM, Weiwei Xiong < >> xion...@gmail.com> >> >> >>> >> wrote: >> >> >>> >> > Hi, >> >> >>> >> > >> >> >>> >> > I recently set up a 2-node Hadoop and HBase cluster and am >> trying >> >> >>> >> > to >> >> >>> >> > load >> >> >>> >> > data into my HBase table using HBase client. >> >> >>> >> > >> >> >>> >> > The issue bothers me is that the data are always written into >> one >> >> >>> >> > node of >> >> >>> >> > the cluster, i.e., all the regions of the hbase table are on >> one >> >> >>> >> > node. >> >> >>> >> > >> >> >>> >> > Is there any configuration I need to change for make the load >> >> >>> >> > balanced? >> >> >>> >> > >> >> >>> >> > Thanks, >> >> >>> >> > -- w >> >> >>> >> > >> >> >>> >> >> >> >>> > >> >> >> >> >> > >> >> > >> > >> > >> >
