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HBase >> mail # user >> Questions about HBase replication


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Re: Questions about HBase replication
On Mon, May 20, 2013 at 3:54 PM, Jean-Daniel Cryans <[EMAIL PROTECTED]>wrote:

> On Mon, May 20, 2013 at 3:48 PM, Varun Sharma <[EMAIL PROTECTED]> wrote:
> > Thanks JD for the response... I was just wondering if issues have ever
> been
> > seen with regards to moving over a large number of WAL(s) entirely from
> one
> > region server to another since that would double the replication related
> > load on the one server which takes over.
>
> We only move the znodes, no data is actually being re-written.
>

Yes, but the region server now has 2X the number of WAL(s) to replicate and
could suffer higher replication lag as a result...

> >
> > Another side question: After the WAL has been replicated - is it purged
> > immediately or soonish from the zookeeper ?
>
> The WAL's znode reference is deleted immediately. The actual WAL will
> be deleted according to the chain of log cleaners.
>
> J-D
>