>From Merge#run():
HBaseAdmin.checkHBaseAvailable(getConf());
LOG.fatal("HBase cluster must be off-line.");
Cheers
On Wed, Nov 20, 2013 at 9:14 AM, Asaf Mesika <asaf.mes...@gmail.com> wrote:
> Thanks! Offline as in table disabled or cluster shutdown?
>
> On Wednesday, November 20, 2013, Tom Brown wrote:
>
> > The trade-off we make is to increase our write performance knowing it
> will
> > negatively impact our read performance. In our case, however, we write a
> > lot of rows that might never be read (depending on the specific deep-dive
> > queries that will be run), so it's an ok trade-off. However, our layout
> is
> > similar to the one described by Mike, so when we perform a read, we don't
> > have to send to every region in the system, only the few that might have
> > the data we need. Bloom filters also make random reads more efficient.
> >
> > Online merge is only available in the 0.96.x code, but an offline merge
> > exists for 0.94.x (that may not be a viable option for you). From the
> > command line:
> >
> > hbase org.apache.hadoop.hbase.util.Merge "table" "region1", "region2"
> >
> > However, if you have a specific weekly time that you can use for offline
> > maintenance, writing a utility that splits the heavily used (hot) regions
> > and merges the empty ones would allow you to balance your regions more
> > appropriately across your cluster.
> >
> > --Tom
> >
> >
> > On Wed, Nov 20, 2013 at 8:43 AM, Otis Gospodnetic <
> > otis.gospodne...@gmail.com> wrote:
> >
> > > We use https://github.com/sematext/HBaseWD and I just learned
> > > Amazon.com people are using it and are happy with it, so it may work
> > > for you, too.
> > >
> > > Otis
> > > --
> > > Performance Monitoring * Log Analytics * Search Analytics
> > > Solr & Elasticsearch Support * http://sematext.com/
> > >
> > >
> > > On Wed, Nov 20, 2013 at 1:00 AM, Asaf Mesika <asaf.mes...@gmail.com>
> > > wrote:
> > > > Thanks for clearing that out.
> > > > I'm using your message to ping anyone who assist as to it appears the
> > use
> > > > case should happen to a lot of people?
> > > >
> > > > Thanks!
> > > >
> > > > On Wednesday, November 20, 2013, Himanshu Vashishtha wrote:
> > > >
> > > >> Re: "The 32 limit makes HBase go into
> > > >> stress mode, and dump all involving regions contains in those 32 WAL
> > > >> Files."
> > > >>
> > > >> Pardon, I haven't read all your data points/details thoroughly, but
> > the
> > > >> above statement is not true. Rather, it looks at the oldest WAL
> file,
> > > and
> > > >> flushes those regions which would free that WAL file.
> > > >>
> > > >> But I agree that in general with this kind of workload, we should
> > handle
> > > >> WAL files more intelligently and free up those WAL files which don't
> > > have
> > > >> any dependency (that is, all their entries are already flushed) when
> > > >> archiving. We do that in trunk but not in any released version,
> > though.
> > > >>
> > > >>
> > > >>
> > > >> On Sat, Nov 16, 2013 at 11:16 AM, Asaf Mesika <
> asaf.mes...@gmail.com>
> > > >> wrote:
> > > >>
> > > >> > First I forgot to mention that <customerId> in our case is
> > > >> > MD5(<customerId>).
> > > >> > In our case, we have so much data flowing in, that we end up
> having
> > a
> > > >> > region per <customerId><bucket> pretty quickly and even that, is
> > > splitted
> > > >> > into different regions by specific date duration (timestamp).
> > > >> >
> > > >> > We're not witnessing a hotspot issue. I built some scripts in java
> > and
> > > >> awk,
> > > >> > and saw that 66% of our customers use more than 1Rs.
> > > >> >
> > > >> > We have two main serious issues: primary and secondary.
> > > >> >
> > > >> > Our primary issue being the slow-region vs fast-region. First
> let's
> > be
> > > >> > reminded that a region represents as I detailed before a specific
> > > >> > <customerId><bucket>. Some customers gets x50 times more data that
> > > other
> > > >> > customers at a specific time frame (2hrs - 1 day). So in a one RS,
> > we
> > > >> have
> > > >> > regions getting 10 write requests per hour, vs 50k write requests
> > per
> > > >> hour.
> > > >> > So the region mapped to the slow-filling customer id, doesn't get
> to
> > > the
> > > >> > 256MB flush limit and hence isn't flushed, while the regions
> mapped
> > to
> > > >> the
> > > >> > fast-filling customer id, are flushing very quickly since they are
> > > >> filling
> > > >> > very quickly.
> > > >> > Let's say the 1st WAL file contains the put of a slow-filling
> > > customerId.
> > > >> > the fast-filling customerId, fills up the rest of that file. After
> > > 20-30
> > > >> > seconds, the file gets rolled, and another file fills up with fast
> > > >> filling
> > > >> > customerId. After a while, we get to 32 WAL Files. The 1st file
> > wasn't
> > > >> > deleted since its region wasn't flushed. The 32 limit makes HBase
> go
> > > into
> > > >> > stress mode, and dump all involving regions contains in those 32
> WAL
> > > >> Files.
> > > >> > In our case, we saw that it flushes 111 regions. Lots of the store
> > > files
> > > >> > are 3k-3mb sized. So our compaction queue start filling up with
> > those
> > > >> store
> > > >> > files needs to be compacted.
> > > >> > At the of the road, th
>
