Hey Koji,
It's an expensive operation - for the secondary namenode, not the
namenode itself, right? I don't particularly care if I stress out a
dedicated node that doesn't have to respond to queries ;)
Locally we checkpoint+backup fairly frequently (not 5 minutes ...
maybe less than the default hour) due to sheer paranoia of losing
metadata.
Brian
On May 14, 2009, at 12:25 PM, Koji Noguchi wrote:
The secondary namenode takes a snapshot
at 5 minute (configurable) intervals,
This is a bit too aggressive.
Checkpointing is still an expensive operation.
I'd say every hour or even every day.
Isn't the default 3600 seconds?
Koji
-----Original Message-----
From: jason hadoop [mailto:jason.had...@gmail.com]
Sent: Thursday, May 14, 2009 7:46 AM
To: core-user@hadoop.apache.org
Subject: Re: Setting up another machine as secondary node
any machine put in the conf/masters file becomes a secondary namenode.
At some point there was confusion on the safety of more than one
machine,
which I believe was settled, as many are safe.
The secondary namenode takes a snapshot at 5 minute (configurable)
intervals, rebuilds the fsimage and sends that back to the namenode.
There is some performance advantage of having it on the local machine,
and
some safety advantage of having it on an alternate machine.
Could someone who remembers speak up on the single vrs multiple
secondary
namenodes?
On Thu, May 14, 2009 at 6:07 AM, David Ritch <david.ri...@gmail.com>
wrote:
First of all, the secondary namenode is not a what you might think a
secondary is - it's not failover device. It does make a copy of the
filesystem metadata periodically, and it integrates the edits into
the
image. It does *not* provide failover.
Second, you specify its IP address in hadoop-site.xml. This is where
you
can override the defaults set in hadoop-default.xml.
dbr
On Thu, May 14, 2009 at 9:03 AM, Rakhi Khatwani
<rakhi.khatw...@gmail.com
wrote:
Hi,
I wanna set up a cluster of 5 nodes in such a way that
node1 - master
node2 - secondary namenode
node3 - slave
node4 - slave
node5 - slave
How do we go about that?
there is no property in hadoop-env where i can set the ip-address
for
secondary name node.
if i set node-1 and node-2 in masters, and when we start dfs, in
both the
m/cs, the namenode n secondary namenode processes r present. but i
think
only node1 is active.
n my namenode fail over operation fails.
ny suggesstions?
Regards,
Rakhi
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