Re: The case of PostgreSQL on NFS Server (II)

On Fri, Apr 3, 2015 at 1:40 AM, Octavi Fors <octavi(at)live(dot)unc(dot)edu> wrote:
> Hi David, John et al.,
<snip>
> Oops, sorry yes I think I may "miss-spoke" when explaining my second reason
> why not choosing eSATA.
> My situation is the following:
>
> -Two computers (C1 & C2) and NAS (with no eSATA I/O) on the same LAN.
> -C1 acquires images from a telescope and periodically stores them via NFS in
> the NAS (no database involved here, just in the ext4 filesystem).
> -C2 is a 12 xeon core-class server designed to analyze the stored images in
> the NAS, and compute astrometry & photometry measurements (catalogs & light
> curves) for every star & image. These measurements are inserted in the
> catalogs database inside the NAS.
>
> Therefore there's only *one* computer (C2) which will run postgresql server
> with the tablespace onNAS.
>
> So does this approach sound like feasible if the NFS parameters are set
> properly?

OK, it is very understandable why the images are on the NAS. It is the
easiest way to share them. I guess you want the DB on the NAS simply
because you don't have sufficient disk space on the disks connected to
C2.

>
<snip>
> Could you confirm that
> nas_ip:/volume1/data /home/ofors/Documents/nas nfs noac,sync
> would be good options for /etc/fstab?
>
> Any additional NFS parameter?

Have you done a web search on "NFS Performance"? I got some good hits
with Google.
http://www.tldp.org/HOWTO/NFS-HOWTO/performance.html (a bit old, I've
been told)
http://www.cyberciti.biz/faq/linux-unix-tuning-nfs-server-client-performance/

Mentions "noatime" and "nodiratime" to not update the last access
date/time on files & directories, saving bandwidth. A good explanation
of the NFS mount options, IMO, are on this site:
http://www.dbaexpert.com/blog/nfs-options-for-performance/

Some interesting "speed test" code:
https://github.com/sabujp/nfsSpeedTest

>
<snip>
> Thanks a lot in advance,
> --
> Octavi Fors

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