seperate swap drive, was Re: [ADMIN] Speed problem

Hi Tony and all

Well, first I want to say that none of my databases are bigger then a few
meg of data, so I may not be the most experianced here.

That said ...

On Wed, 4 Nov 1998, Tony Reina wrote:

> Terry Mackintosh wrote:
>
> > Note, with a table that big your swap space should be on a physically
> > differant hard drive (from the db) so that the db and the swap are not
> > always fighting for the use of the drive heads.
> >
>
> Terry,
>
>     I have a rather large database as well (> 2 Meg of tuples). I thought
> my system was souped up enough: PII/400 MHz (100 MHz bus) 256 Meg SDRAM,
> 18 Gig SCSI harddrive, Red Hat Linux 5.1. However, my swap space (512
> Meg) is on the same harddrive as the database (albeit on a separate
> partition). It sounds like you are saying that this is a no-no.

Just that under heavy loads it may degrade performance as you yourself
mention.

>     The database runs quite fast except with processes involving repetitive
> inserts or updates. With each successive update in a continuous process,
> the speed drops (almost like an exponentially decreasing process). Plus,
> when this happens, I can't really use the computer that runs the
> database because it is soooooo slow. When I run top, the computer is
> using all 256 Meg of memory and going about 30-40 meg into swap space.
> >From what you've suggested, this 30-40 meg of swap is also competing
> with the database trying to write to the harddrive (since they are using
> the same head).

This is the type of performance degradation I was referring to.

>     If I put in a second drive exclusively for the swap space, could this
> increase my speed? Or, would it be better to invest in more RAM so that
> the job wouldn't need to use any swap space at all?

Why not both? :-)

> Thanks.
> -Tony
>

Terry Mackintosh <terry@terrym.com>          http://www.terrym.com
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