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Date: Fri, 15 Jun 2012 15:45:41 -0400
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Subject: Re: forceSync=no
From: Raj N <raj.cassandra@gmail.com>
To: user@zookeeper.apache.org
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Thanks Patrick. So back to my original question. Will forceSync=no cause a
zookeeper node to not start up cleanly if it crashed? It doesn't happen all
the time. But it happened to me once. I had to cleanup all the transaction
logs on all the nodes and then bring the nodes back up. For my use case I
can tolerate losing data in the worst case scenario since I can regenerate
all the data. But I should be able to tolerate a single point of failure as
long as the node comes back up cleanly. Can zookeeper recover from a
corrupt transaction log using existing snapshots and then replaying
messages from its peers?

Thanks
-Raj

On Fri, Jun 15, 2012 at 2:17 PM, Patrick Hunt <phunt@apache.org> wrote:

> For a single node failure I believe so.
>
> Patrick
>
> On Thu, Jun 14, 2012 at 11:56 AM, Raj N <raj.cassandra@gmail.com> wrote:
> > Sorry, I should have been more specific. By corrupt, I mean that the
> > zookeeper node doesn't come back up on a restart. I would have imagined
> > that zookeeper would sync the lost transactions from its peers. I agree I
> > will have a problem if I have multiple failures. But for a single node
> > failure in a 3-node ensemble, I should be able to recover even if
> > forceSync=no.
> >
> > Thanks
> > -Raj
> >
> > On Thu, Jun 14, 2012 at 1:03 PM, Jonathan Simms <slyphon@gmail.com>
> wrote:
> >
> >> There's a big warning in the documentation that says that's a
> possibility.
> >> If you don't force both Java and the OS to flush their IO buffers to
> disk,
> >> then you have no guarantees that your data is consistent.
> >>
> >> On 6/14/12 10:56 AM, "Raj N" <raj.cassandra@gmail.com> wrote:
> >>
> >> >Are you guys aware of any issues with forceSync=no that could cause the
> >> >transaction log to get corrupted on a zookeeper crash.
> >> >
> >> >Thanks
> >> >-Raj
> >>
> >>
> >>
>

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