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From:Scott Tanner Date:October 8 2007 2:07pm
Subject:Re: SAN and ibdata files
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Rajan,
  I believe you are talking about a NAS setup, which is different from
the SAN configuration I was referring to. Check out 
http://www.nas-san.com/differ.html for a quick comparison.

  With NFS volumes, your adding several layers of overhead when
accessing the disks which has a drastic effect on performance. I'm not
sure what the exact locking issue would be, but I'd imagine it would
have to do with the added latency.

  I have heard of a few people using NFS on small, mostly read databases
though. So you may not have any issues depending on the type and amount
of usage your server would be getting.

Regards,
Scott

On Mon, 2007-10-08 at 18:06 +0530, Ace wrote:
> Yes Scott! Only thing that confused and still confusing me is the following
> note on mysql site -
> 
> "*Note*
> It is not a good idea to configure InnoDB to use datafiles or logfiles on
> NFS volumes. Otherwise, the files might be locked by other processes and
> become unavailable for use by MySQL. "
> 
> http://dev.mysql.com/doc/refman/5.0/en/innodb-configuration.html
> 
> Why other processes will keep files locked if its on NFS volumes? and which
> are the processes they are referring?
> 
> Thanks,
> Rajan
> 
> On 10/8/07, Scott Tanner <stanner@stripped> wrote:
> >
> > Rajan,
> > In a SAN configuration, the lun/volume should appear just like a
> > locally attached physical disk on your server. MySQL will not need any
> > special configurations to access it, just poiint the datadir to the SAN
> > disk.
> >
> > Regards,
> > Scott Tanner
> >
> >
> > On Mon, 2007-10-08 at 11:06 +0530, Ace wrote:
> > > Thanks Dan! We do know the permission problem. We tried chown but got
> > "Not a
> > > owner" error. That is because of "root squashing" in which root becomes
> > > "nobody" when you cd to NFS directory.
> > >     To overcome this we tried adding "no_root_squash" to export file.
> > but
> > > still the error.
> > >
> > > I will overcome this somehow.....but my Biggest worry now is - can I
> > > configure Mysql to use SAN location? if not, why?
> > >
> > > Thanks,
> > > Rajan
> > > On 10/7/07, Dan Nelson <dnelson@stripped> wrote:
> > > >
> > > > In the last episode (Oct 06), Ace said:
> > > > > Hi Experts,
> > > > >
> > > > >       You all know the size problems with ibdata and log files.
> We
> > plan
> > > > to
> > > > > move those files to SAN to have maximum storage possible. We did
> so
> > with
> > > > > configuration changes in my.cnf files to save log and ibdata
> files
> > on
> > > > SAN
> > > > > location. But got following error -
> > > > >
> > > > > InnoDB: Unable to lock /opsolnfs/mysql/ibdata1, error: 13
> > > > > InnoDB: Check that you do not already have another mysqld
> process
> > > > > InnoDB: using the same InnoDB data or log files.
> > > > >
> > > > >        Any concrete steps to overcome this problem? Your input
> will
> > add
> > > > > value in solving our problem.
> > > >
> > > > $ perror 13
> > > > OS error code  13:  Permission denied
> > > >
> > > > Check permissions on your data directory.
> > > >
> > > > --
> > > >        Dan Nelson
> > > >        dnelson@stripped
> > > >
> >

Thread
SAN and ibdata filesAce6 Oct
  • Re: SAN and ibdata filesDan Nelson7 Oct
    • Re: SAN and ibdata filesAce8 Oct
      • Re: SAN and ibdata filesScott Tanner8 Oct
        • Re: SAN and ibdata filesAce8 Oct
          • Re: SAN and ibdata filesScott Tanner8 Oct
      • Re: SAN and ibdata filesDan Nelson8 Oct