hbase-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Vladimir Rodionov <vladrodio...@gmail.com>
Subject Re: hbase hdfs snapshots
Date Sat, 11 Jul 2015 00:06:22 GMT
Being not very familiar with snapshot code, I could speculate only on where
most time is spent ...

In creating 60K x 4 x K (K is average # of store files per region) small
HFileLInks? This can be very large # of files.

-Vlad



On Fri, Jul 10, 2015 at 4:57 PM, Matteo Bertozzi <theo.bertozzi@gmail.com>
wrote:

> the total time taken by a snapshot should be bounded by the slowest
> machine.
> we send a notification to each RS and each RS execute the snapshot
> operation for each region.
> can you track down what is slow in your case?
>
> clone has to create a reference for each file, and that is a master
> operation, and these calls may all go away if we change the layout in a
> proper way instead of doing what is proposed in HBASE-13991.
> Most of the time should be spent on the enableTable phase of the clone.
>
>
> On Fri, Jul 10, 2015 at 4:36 PM, Jean-Marc Spaggiari <
> jean-marc@spaggiari.org> wrote:
>
> > Hi Rahul,
> >
> > Have you identified with it takes those 30 minutes? Is the table balances
> > correctly across the servers? Form the logs, are you able to identify
> what
> > takes that much time?
> >
> > JM
> >
> > 2015-07-10 18:46 GMT-04:00 rahul gidwani <rahul.gidwani@gmail.com>:
> >
> > > Hi Matteo,
> > >
> > > We do SKIP_FLUSH.  We have 1200+ regionservers with a single table with
> > 60k
> > > regions and 4 column families.  It takes around 30 minutes to snapshot
> > this
> > > table using manifests compared to just seconds doing this with hdfs.
> > > Cloning this table takes considerably longer.
> > >
> > > For cases where someone would want to run Map/Reduce over snapshots
> this
> > > could be much faster as we could take an hdfs snapshot and bypass the
> > > clone.
> > >
> > > rahul
> > >
> > >
> > > On Thu, Jul 9, 2015 at 12:20 PM, Matteo Bertozzi <
> > theo.bertozzi@gmail.com>
> > > wrote:
> > >
> > > > On Thu, Jul 9, 2015 at 12:12 PM, rahul gidwani <
> > rahul.gidwani@gmail.com>
> > > >  wrote:
> > > >
> > > > > Even with manifests (Snapshot V2) for our larger tables it can take
> > > hours
> > > > > to Snapshot and Clone a table.
> > > > >
> > > >
> > > > on snapshot time the only thing that can take hours, is "flush".
> > > > if you don't need that (which is what you get with hdfs snapshots)
> you
> > > can
> > > > specify SKIP_FLUSH => true
> > > >
> > > >
> > > > Matteo
> > > >
> > > >
> > > > On Thu, Jul 9, 2015 at 12:12 PM, rahul gidwani <
> > rahul.gidwani@gmail.com>
> > > > wrote:
> > > >
> > > > > HBase snapshots are a very useful feature. but it was implemented
> > back
> > > > > before there was the ability to snapshot via HDFS.
> > > > >
> > > > > Newer versions of Hadoop support HDFS snapshots.  I was wondering
> if
> > > the
> > > > > community would be interested in something like a Snapshot V3 where
> > we
> > > > use
> > > > > HDFS to take these snapshots.
> > > > >
> > > > > Even with manifests (Snapshot V2) for our larger tables it can take
> > > hours
> > > > > to Snapshot and Clone a table.
> > > > >
> > > > > Would this feature be of use to anyone?
> > > > >
> > > > > thanks
> > > > > rahul
> > > > >
> > > >
> > >
> >
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message