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HBase, mail # user - more regionservers does not improve performance


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Re: more regionservers does not improve performance
Matt Corgan 2012-10-14, 05:37
Did you try setting put.setWriteToWAL(false) as Bryan suggested?  This may
not be what you want in the end, but seeing what happens may help debug.

Matt

On Sat, Oct 13, 2012 at 8:58 AM, Jonathan Bishop <[EMAIL PROTECTED]>wrote:

> Suraj,
>
> I bumped my regionservers all the way up to 32g from 8g. They are running
> on 64g and 128g machines on our cluster. Unfortunately, the machines all
> have various states of loading (usually high) from other users.
>
> In ganglia I do not see any swapping, but that has been known to happen
> from time to time.
>
> Thanks for your help - I'll take a look at your links.
>
> Jon
>
> On Fri, Oct 12, 2012 at 7:30 PM, Suraj Varma <[EMAIL PROTECTED]> wrote:
>
> > Hi Jonathan:
> > What specific metric on ganglia did you notice for "IO is spiking"? Is
> > it your disk IO? Is your disk swapping? Do you see cpu iowait spikes?
> >
> > I see you have given 8g to the RegionServer ... how much RAM is
> > available total on that node? What heap are the individual mappers &
> > DN set to run on (i.e. check whether you are overallocated on heap
> > when the _mappers_ run ... causing disk swapping ... leading to IO?).
> >
> > There can be multiple causes ... so, you may need to look at ganglia
> > stats and narrow the bottleneck down as described in
> > http://hbase.apache.org/book/casestudies.perftroub.html
> >
> > Here's a good reference for all the memstore related tweaks you can
> > try (and also to understand what each configuration means):
> > http://blog.sematext.com/2012/07/16/hbase-memstore-what-you-should-know/
> >
> > Also, provide more details on your schema (CFs, row size), Put sizes,
> > etc as well to see if that triggers an idea from the list.
> > --S
> >
> >
> > On Fri, Oct 12, 2012 at 12:46 PM, Bryan Beaudreault
> > <[EMAIL PROTECTED]> wrote:
> > > I recommend turning on debug logging on your region servers.  You may
> > need
> > > to tune down certain packages back to info, because there are a few
> > spammy
> > > ones, but overall it helps.
> > >
> > > You should see messages such as "12/10/09 14:22:57 INFO
> > > regionserver.HRegion: Blocking updates for 'IPC Server handler 41 on
> > 60020'
> > > on region XXX: memstore size 256.0m is >= than blocking 256.0m size".
>  As
> > > you can see, this is an INFO anyway so you should be able to see it now
> > if
> > > it is happening.
> > >
> > > You can try upping the number of IPC handlers and the memstore flush
> > > threshold.  Also, maybe you are bottlenecked by the WAL.  Try doing
> > > put.setWriteToWAL(false), just to see if it increases performance.  If
> so
> > > and you want to be a bit more safe with regard to the wal, you can try
> > > turning on deferred flush on your table.  I don't really know how to
> > > increase performance of the wal aside from that, if this does seem to
> > have
> > > an affect.
> > >
> > >
> > >
> > > On Fri, Oct 12, 2012 at 3:15 PM, Jonathan Bishop <
> [EMAIL PROTECTED]
> > >wrote:
> > >
> > >> Kevin,
> > >>
> > >> Sorry, I am fairly new to HBase. Can you be specific about what
> > settings I
> > >> can change, and also where they are specified?
> > >>
> > >> Pretty sure I am not hotspotting, and increasing memstore does not
> seem
> > to
> > >> have any effect.
> > >>
> > >> I do not seen any messages in my regionserver logs concerning
> blocking.
> > >>
> > >> I am suspecting that I am hitting some limit in our grid, but would
> > like to
> > >> know where that limit is being imposed.
> > >>
> > >> Jon
> > >>
> > >> On Fri, Oct 12, 2012 at 6:44 AM, Kevin O'dell <
> [EMAIL PROTECTED]
> > >> >wrote:
> > >>
> > >> > Jonathan,
> > >> >
> > >> >   Lets take a deeper look here.
> > >> >
> > >> > What is your memstore set at for the table/CF in question?  Lets
> > compare
> > >> > that value with the flush size you are seeing for your regions.  If
> > they
> > >> > are really small flushes is it all to the same region?  If so that
> is
> > >> going
> > >> > to be schema issues.  If they are full flushes you can up your