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From Stas Oskin <stas.os...@gmail.com>
Subject Re: Secondary NameNodes or NFS exports?
Date Wed, 23 Dec 2009 19:23:33 GMT
Hi.

What was your solution to this then?

Regards.

On Sat, Dec 5, 2009 at 7:43 AM, Jason Venner <jason.hadoop@gmail.com> wrote:

> 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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