SGreenunimin.com
Date: Wed Jul 06 2005 - 11:14:58 CDT

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Ruben Carvalho <carvalho_rubenyahoo.co.uk> wrote on 07/06/2005 11:06:10
AM:

> I think I haven't understood your question. I guess
> that in case of a network failure you can have the
> same behavior as a power shutdown.
>
> About the networked drives? Anyone?
>
>
> --- Martijn Tonies <m.toniesupscene.com> wrote:
>
> > Hi Ruben,
> >
> > > I would like to make a short, quick and simple
> > > question.
> > >
> > > Is it possible to have the following line:
> > >
> > > innodb_data_home_dir="X:/data/"
> > >
> > > in a my.ini config file?
> > >
> > > I'm using windows XP, mysql 4.1.12, X: is a mapped
> > > network drive to a Linux folder using samba, all
> > the
> > > permissions are set and tested.
> > >
> > > I have seen this posted many times but without
> > many
> > > replies. I want to use a folder in a mapped drive
> > to
> > > save my InnoDB data. Is this possible?
> >
> > I don't know this particular answer for MySQL, but I
> > do have 1 question:
> >
> > If the database engine doesn't have control over the
> > files
> > and/or drive, what should it do in the case of a
> > network
> > failure?
> >
> > Let alone the latency of a networked file...
> >
> > With regards,
> >
> > Martijn Tonies
> > Database Workbench - tool for InterBase, Firebird,
> > MySQL, Oracle & MS SQL
> > Server
> > Upscene Productions
> > http://www.upscene.com
> > Database development questions? Check the forum!
> > http://www.databasedevelopmentforum.com
> >
> >
>
>
> Rúben Carvalho

RDBMS over a network: NOT recommended. Not only can you not enforce
OS-level locking on your files (maybe you can, I guess it may depend on
your device and inteface protocols) but the MOST COMMON bottleneck to
database performance is disk I/O. If you went with networked storage, you
are not only going to suffer through disk lag (seek time + rotational
positioning before the operation can start) but you are incurring network
overhead on top of it IN BOTH DIRECTIONS.

Unless your network device is flash-only (all memory, no disks), you just
cut your throughput by at least 75%. And even if your device is flash-only
you will reduce your data throughput by 25-50% (all performance numbers
are rough estimates pulled out of my a** but based on the number of extra
network hops necessary to get at and read your files).

I don't care how fast your network is, networked storage can't be as fast
as local disks. Again, it is highly discouraged to use networked storage
for anything but the most trivial database uses (small file sizes, low
traffic, etc). For any application that requires even modest performance,
spend your money on a fast RAID configuration. You will be much happier in
the long run.

Shawn Green
Database Administrator
Unimin Corporation - Spruce Pine

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