Re: Is nfs reliable?

Thanks to everyone for all the great replies and information.

On Fri, Jun 3, 2016 at 4:08 PM, Matt <mvshelton_at_chartermi.net> wrote:

> Ok Let me clarify if you setup and manage nfs mounts correctly they are
> extremely stable. If you do not setup the nfs mounts correctly in my
> experience they are not reliable. If you are going to use NFS mounts to
> support your environment please spend the time and set them up correctly.
>
>
>
> Thanks, Matt
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *Mark W. Farnham
> *Sent:* Friday, June 3, 2016 5:20 PM
> *To:* tim_at_evdbt.com; mvshelton_at_chartermi.net; rfreeman_at_businessolver.com;
> 'Michael Cunningham'
> *Cc:* 'oracle-l_at_freelists org'
> *Subject:* RE: Is nfs reliable?
>
>
>
> First, I agree with and applaud Tim regarding his careful and accurate
> description of NFS, TCP, and UDP.
>
>
>
> Second, I’ll note that Matt added the word “mounts” to his comment. IF it
> is the mounts specifically to which Matt refers, there has been a spotty
> history over time and releases of various operating systems about whether
> you could rely on particular mount point naming, addressing, and
> characteristics across normal and failure mode operating system reboots. I
> believe that is mostly in the past, but I cannot assure you Matt is wrong,
> because a) no one can enumerate that they are reliably present across all
> combinations, and b) Matt could be referencing particular IT shop mount
> point activation processes that were apparently broken at a particular
> organization.
>
>
>
> But back to Tim’s point: If you chose the right protocol (and mount
> reliably) you will be up to industry standard on the reliability front.
>
>
>
> As Tim mentioned earlier in the thread it is quite possible to configure
> nfs over transport that is “lossy.” If you are using Oracle that would be a
> poor choice for at least database files and redo logs. Likewise, a bone
> head order of reboot could start oracle before some of the required mount
> are made and in reboot software that forks parallel operations in the
> restart hilarity can result if restarting Oracle is not definitely serially
> after establishing the mount points on which it relies and you thereby
> produce a race condition that appears to the casual observer to not be
> deterministic. So nfs CAN be unreliable, but it does not have to be and it
> is not rocket science to get it right. Likewise nfs mounts.
>
>
>
> Sorry to be long-winded, but I really didn’t want any folks who have
> observed “nfs mount point failure” and therefore “know” nfs is not reliable
> to become confused as to whether Tim was wrong in any regard about his
> careful and accurate description of NFS, TCP, and UDP.
>
>
>
> mwf
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [
> mailto:oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org>] *On
> Behalf Of *Tim Gorman
> *Sent:* Friday, June 03, 2016 4:37 PM
> *To:* mvshelton_at_chartermi.net; rfreeman_at_businessolver.com; 'Michael
> Cunningham'
> *Cc:* 'oracle-l_at_freelists org'
> *Subject:* Re: Is nfs reliable?
>
>
>
> Matt,
>
> I respectfully disagree; there is indeed an easy answer.
>
> First, the term "reliable" is ambiguous and must be clarified before
> engaging in a meaningful discussion. In this discussion, I believe the
> term "reliable" is not defined as the "absence of failure", but instead as
> "loss-less transmission of data", with "loss-less" meaning "complete and
> accurate".
>
> TCP and UDP are alternative protocols residing at layer 4 (transport) of
> the 7-layer OSI model <https://en.wikipedia.org/wiki/OSI_model>. The
> first three layers of the OSI model define the hardware carrier, structure,
> framing, addressing, and routing of data, and it is at the transport layer
> that the branch between loss-less and loss-y session protocols is
> implemented.
>
> NFS is implemented at level 7 (application) of the model, and so the
> question of "reliability" (as I believe we are discussing it) has been
> resolved several layers down.
>
> In any context (analog, digital, or human), "reliable" never means
> "perfect". Error, loss, and corruption is always possible for a myriad of
> reasons, applying equally to any protocol. TCP is "loss-less" by design,
> but no design is absolutely perfect.
>
> Hope this helps!
>
> -Tim
>
> On 6/3/16 13:17, Matt wrote:
>
> I do not think there is an easy answer whether or not nfs mounts are
> reliable. IT depends upon your organization infrastructe teams. I have
> worked at organizations were my nfs mounts were completely unreliable. My
> current organization I cannot remember the last time I have had an issue
> with my nfs mounts.
>
>
>
> Thanks, Matt
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [
> mailto:oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org>] *On
> Behalf Of *Robert Freeman
> *Sent:* Friday, June 3, 2016 1:31 PM
> *To:* Michael Cunningham
> *Cc:* oracle-l_at_freelists org
> *Subject:* RE: Is nfs reliable?
>
>
>
> I would not have an issue with monitoring scripts… However, anything
> diagnostic or the like I’d keep on local storage…
>
>
>
> *From:* Michael Cunningham [mailto:napacunningham_at_gmail.com
> <napacunningham_at_gmail.com>]
> *Sent:* Friday, June 03, 2016 11:30 AM
> *To:* Robert Freeman <rfreeman_at_businessolver.com>
> *Cc:* oracle-l_at_freelists org <oracle-l_at_freelists.org>
> *Subject:* Re: Is nfs reliable?
>
>
>
> Robert, how would you feel about having a library of monitoring scripts on
> an nfs mount? I do this so that scripts are available on every Oracle
> server. I also backup config files, etc. to this mount making it easy for
> me to scan, in a single directory, something like all cron backup files to
> see where something is running. It's these things why I feel the nfs mount
> serves a great benefit. And many others...
>
>
>
> Michael
>
>
>
> On Fri, Jun 3, 2016 at 8:34 AM, Robert Freeman <rfreeman_at_businessolver.com>
> wrote:
>
> Mike,
>
>
>
> We Run our RAC databases using NFS as the shared media for datafiles. We
> have yet to have a failure because of NFS. We don’t use shared software
> directories however, just local directories.
>
> My personal preference is for local software.
>
>
> RF
>
>
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *Michael Cunningham
> *Sent:* Friday, June 03, 2016 12:02 AM
> *To:* oracle-l_at_freelists org <oracle-l_at_freelists.org>
> *Subject:* Is nfs reliable?
>
>
>
> I had someone tell me today that nfs should not be relied on and it should
> not be used for a shared mount that needed to be reliably available.
>
>
>
> Has anyone ever hear this before?
>
>
>
> --
>
> Michael Cunningham
>
>
>
>
>
> --
>
> Michael Cunningham
>
>
>

-- 
Michael Cunningham

--
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