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From Jason Venner <jason.had...@gmail.com>
Subject Re: Secondary NameNodes or NFS exports?
Date Sat, 05 Dec 2009 05:43:43 GMT
I have dug into this more, it turns out the problem is unrelated to nfs or
solaris.
The issue is that if there is a meta data change, while the secondary is
rebuilding the fsimage, the rebuilt image is rejected.
On our production cluster, there is almost never a moment where there is not
a file being created or altered, and as such the secondary is never make a
fresh fsimage for the cluster.

I have checked this with several hadoop variants and with vanilla
distributions with the namenode, secondary and a datanode all running on the
same machine.

On Tue, Oct 27, 2009 at 8:03 PM, Jason Venner <jason.hadoop@gmail.com>wrote:

> The namenode would never accept the rebuild fsimage from the secondary, so
> the edit logs grew with outbounds.
>
>
> On Tue, Oct 27, 2009 at 10:51 AM, Stas Oskin <stas.oskin@gmail.com> wrote:
>
>> Hi.
>>
>> You mean, you couldn't recover the NameNode from checkpoints because of
>> timestamps?
>>
>> Regards.
>>
>> On Tue, Oct 27, 2009 at 4:49 PM, Jason Venner <jason.hadoop@gmail.com
>> >wrote:
>>
>> > We have been having some trouble with the secondary on a cluster that
>> has
>> > one edit log partition on an nfs server, with the namenode rejecting the
>> > merged images due to timestamp missmatches.
>> >
>> >
>> > On Mon, Oct 26, 2009 at 10:14 AM, Stas Oskin <stas.oskin@gmail.com>
>> wrote:
>> >
>> > > Hi.
>> > >
>> > > Thanks for the advice, it seems that the initial approach of having
>> > single
>> > > SecNameNode writing to exports is the way to go.
>> > >
>> > > By the way, I asked this already, but wanted to clarify:
>> > >
>> > > * It's possible to set how often SecNameNode checkpoints the data
>> (what
>> > is
>> > > the setting by the way)?
>> > >
>> > > * It's possible to let NameNode write to exports as well together with
>> > > local
>> > > disk, which ensures the latest possible meta-data in case of disk
>> crash
>> > > (compared to pereodic check-pointing), but it's going to slow down the
>> > > operations due to network read/writes.
>> > >
>> > > Thanks again.
>> > >
>> > > On Thu, Oct 22, 2009 at 10:03 PM, Patrick Angeles
>> > > <patrickangeles@gmail.com>wrote:
>> > >
>> > > > From what I understand, it's rather tricky to set up multiple
>> secondary
>> > > > namenodes. In either case, running multiple 2ndary NNs doesn't get
>> you
>> > > > much.
>> > > > See this thread:
>> > > >
>> http://www.mail-archive.com/core-user@hadoop.apache.org/msg06280.html
>> > > >
>> > > > On Wed, Oct 21, 2009 at 10:44 AM, Stas Oskin <stas.oskin@gmail.com>
>> > > wrote:
>> > > >
>> > > > > To clarify, it's either let single SecNameNode to write to
>> multiple
>> > NFS
>> > > > > exports, or actually have multiple SecNameNodes.
>> > > > >
>> > > > > Thanks again.
>> > > > >
>> > > > > On Wed, Oct 21, 2009 at 4:43 PM, Stas Oskin <stas.oskin@gmail.com
>> >
>> > > > wrote:
>> > > > >
>> > > > > > Hi.
>> > > > > >
>> > > > > > I'm want to keep a checkpoint data on several separate machines
>> for
>> > > > > backup,
>> > > > > > and deliberating between exporting these machines disks
via NFS,
>> or
>> > > > > actually
>> > > > > > running Secondary Name Nodes there.
>> > > > > >
>> > > > > > Can anyone advice what would be better in my case?
>> > > > > >
>> > > > > > Regards.
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> >
>> > --
>> > Pro Hadoop, a book to guide you from beginner to hadoop mastery,
>> > http://www.amazon.com/dp/1430219424?tag=jewlerymall
>> > www.prohadoopbook.com a community for Hadoop Professionals
>> >
>>
>
>
>
> --
> Pro Hadoop, a book to guide you from beginner to hadoop mastery,
> http://www.amazon.com/dp/1430219424?tag=jewlerymall
> www.prohadoopbook.com a community for Hadoop Professionals
>



-- 
Pro Hadoop, a book to guide you from beginner to hadoop mastery,
http://www.amazon.com/dp/1430219424?tag=jewlerymall
www.prohadoopbook.com a community for Hadoop Professionals

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