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From "Jim Kellerman (POWERSET)" <Jim.Keller...@microsoft.com>
Subject RE: log replication in hbase
Date Tue, 21 Oct 2008 18:13:16 GMT
> -----Original Message-----
> From: Ski Gh3 [mailto:skigh3@gmail.com]
> Sent: Tuesday, October 21, 2008 10:43 AM
> To: hbase-user@hadoop.apache.org
> Subject: Re: log replication in hbase
>
> The last "yes" is contradictary with the previous one...
> So I take this redo log is the WAL log?

Yes.

> It is written to HDFS (replicated three times) rather than stored on the
> regionserver itself locally?

Yes.

> Thanks!
> On Mon, Oct 20, 2008 at 9:33 PM, stack <stack@duboce.net> wrote:
>
> > Ski Gh3 wrote:
> >
> >> Just want to make sure my understanding of the log is correct:
> >>
> >> each regionserver has one log for all the regions it is serving.
> >>
> >>
> >
> > Yes.
> >
> >  this log is the write-ahead log that is stored on hadoop dfs and
> always
> >> written before a data is written to memcache.
> >> is this correct?
> >>
> >>
> >
> > Yes.
> >
> >  I read about a redo log from the mailing list, which says each
> >> regionserver
> >> maintains a redo log locally.
> >> is this the wal log or what is the purpose of this redo log?
> >>
> >>
> > Yes.
> >
> > Sorry for any confusion.  We should be try and be more strict with our
> > nomenclature.
> >
> > St.Ack
> >
> >

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