In trunk this behavior has been improved. Load balancer would move the youngest region off heavily loaded region server.
See http://zhihongyu.blogspot.com/2011/04/load-balancer-in-hbase-090.html I am thinking of creating a new policy for region assignment at cluster startup which assigns regions from each table in round-robin fashion. On Wed, Jun 8, 2011 at 3:04 AM, Kleegrewe, Christian < [email protected]> wrote: > Hi geoff, > > Since hbase balances not at table but at cluster basis it may happen that > all the regions for one table are located at the same region server. The > reason for this may be the way hbase does table splits. If a region exceeds > the configured maximum size the region is split into two, but both resulting > regions are on the same region server. In the background there is a load > balancer running that copies regions between region servers in case that the > cluster gets unbalanced. The region that is copied does not necessarily > belong to the table that you are actually creating. It seems to me that the > regions copied for balancing in most cases do not belong to the table that > is currently created but there is a simple workaround, if you want a > balancing at table level you should disable all the other tables when > generating a the new table. > > regards > > Christian > > ------------------8<-------------------------- > > Siemens AG > Corporate Technology > Corporate Research and Technologies > CT T DE IT3 > Otto-Hahn-Ring 6 > 81739 München, Deutschland > Tel.: +49 (89) 636-42722 > Fax: +49 (89) 636-41423 > mailto:[email protected] > > Siemens Aktiengesellschaft: Vorsitzender des Aufsichtsrats: Gerhard Cromme; > Vorstand: Peter Löscher, Vorsitzender; Roland Busch, Brigitte Ederer, Klaus > Helmrich, Joe Kaeser, Barbara Kux, Hermann Requardt, Siegfried Russwurm, > Peter Y. Solmssen, Michael Süß; Sitz der Gesellschaft: Berlin und München, > Deutschland; Registergericht: Berlin Charlottenburg, HRB 12300, München, HRB > 6684; WEEE-Reg.-Nr. DE 23691322 > > > -----Original Message----- > From: Geoff Hendrey [mailto:[email protected]] > Sent: Tuesday, June 07, 2011 8:34 PM > To: [email protected] > Subject: distribution of regions to servers > > I have a table with a hundred or so regions. When I look in the hbase > web ui, I see that all the regions are on one server. Of course we have > many other tables and lots of data. Some tables seem to distribute their > regions amongst many servers. > > > > I know there probably isn't a "pat" answer to this but: wouldn't I want > a large table with many regions to be distributed across many machines? > Just curious to understand the nuance. If I *do* want a uniform > distribution of regions to servers, how would I achieve it? > > > > -geoff > >
