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From Enis Söztutar <enis....@gmail.com>
Subject Re: oldWALs: what it is and how can I clean it?
Date Thu, 26 Feb 2015 23:48:04 GMT
@Madeleine,

The folder gets cleaned regularly by a chore in master. When a WAL file is
not needed any more for recovery purposes (when HBase can guaratee HBase
has flushed all the data in the WAL file), it is moved to the oldWALs
folder for archival. The log stays there until all other references to the
WAL file are finished. There is currently two services which may keep the
files in the archive dir. First is a TTL process, which ensures that the
WAL files are kept at least for 10 min. This is mainly for debugging. You
can reduce this time by setting hbase.master.logcleaner.ttl configuration
property in master. It is by default 600000. The other one is replication.
If you have replication setup, the replication processes will hang on to
the WAL files until they are replicated. Even if you disabled the
replication, the files are still referenced.

You can look at the logs from master from classes (LogCleaner,
TimeToLiveLogCleaner, ReplicationLogCleaner) to see whether the master is
actually running this chore and whether it is getting any exceptions.

@Liam,
Disabled replication will still hold on to the WAL files because, because
it has a guarantee to not lose data between disable and enable. You can
remove_peer, which frees up the WAL files to be eligible for deletion. When
you re-add replication peer again, the replication will start from the
current status, versus if you re-enable a peer, it will continue from where
it left.



On Thu, Feb 26, 2015 at 12:56 AM, Madeleine Piffaretti <
mpiffaretti@powerspace.com> wrote:

> Hi,
>
> The replication is not turned on HBase...
> Does this folder should be clean regularly? Because I have data from
> december 2014...
>
>
> 2015-02-26 1:40 GMT+01:00 Liam Slusser <lslusser@gmail.com>:
>
> > I'm having this same problem.  I had replication enabled but have since
> > been disabled.  However oldWALs still grows.  There are so many files in
> > there that running "hadoop fs -ls /hbase/oldWALs" runs out of memory.
> >
> > On Wed, Feb 25, 2015 at 9:27 AM, Nishanth S <nishanth.2884@gmail.com>
> > wrote:
> >
> > > Do you have replication turned on in hbase and  if so is your slave
> > >  consuming the replicated data?.
> > >
> > > -Nishanth
> > >
> > > On Wed, Feb 25, 2015 at 10:19 AM, Madeleine Piffaretti <
> > > mpiffaretti@powerspace.com> wrote:
> > >
> > > > Hi all,
> > > >
> > > > We are running out of space in our small hadoop cluster so I was
> > checking
> > > > disk usage on HDFS and I saw that most of the space was occupied by
> > the*
> > > > /hbase/oldWALs* folder.
> > > >
> > > > I have checked in the "HBase Definitive Book" and others books,
> > web-site
> > > > and I have also search my issue on google but I didn't find a proper
> > > > response...
> > > >
> > > > So I would like to know what does this folder, what is use for and
> also
> > > how
> > > > can I free space from this folder without breaking everything...
> > > >
> > > >
> > > > If it's related to a specific version... our cluster is under
> > > > 5.3.0-1.cdh5.3.0.p0.30 from cloudera (hbase 0.98.6).
> > > >
> > > > Thx for your help!
> > > >
> > >
> >
>

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