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Zookeeper, mail # user - zookeeper on SSD


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Re: zookeeper on SSD
Ted Dunning 2012-10-04, 04:28
Yes.

And Patrick's experience is not unexpected.  There is, however, a huge
variation with different types of flash memory.  The software driving the
flash can also result in very different experience.  The experiences that
he alludes to are likely with a conventional SSD packaging of flash driven
via the normal block device emulator.  That can be substantially
sub-optimal, depending on which vendor and configuration you use.

On Thu, Oct 4, 2012 at 5:12 AM, Jun Rao <[EMAIL PROTECTED]> wrote:

> Patrick,
>
> Thanks for the info. Does each ZK write wait for log being flushed to disk?
>
> Jun
>
> On Wed, Oct 3, 2012 at 6:13 PM, Patrick Hunt <[EMAIL PROTECTED]> wrote:
>
> > My experience with SSDs and ZK has been discouraging. SSDs have some
> > really terrible corner cases for latency. I've seen them take 40+
> > seconds (that's not a mistake - seconds) for fsync to complete. When
> > this happened (every few hours) all of the sessions would timeout.
> >
> > See this article:
> > http://storagemojo.com/2012/06/07/the-ssd-write-cliff-in-real-life/
> >
> > Patrick
> >
> > On Wed, Oct 3, 2012 at 9:59 AM, Jun Rao <[EMAIL PROTECTED]> wrote:
> > > Hi,
> > >
> > > Will storing the ZK commit log on SSD improve ZK write latency? Does a
> ZK
> > > write wait until data is flushed to disk?
> > >
> > > Thanks,
> > >
> > > Jun
> >
>