Re: [GENERAL] advice on buying sun hardware to run postgres

On Wed, 28 Apr 1999, Chris Bitmead wrote:

// Umm. SCSI or no SCSI, if the disk's cache is full and it has to go
// away and write stuff, then nobody is going to be able to read
// anything while this is happening. SCSI disks can't defy the laws of
// physics. So the OS is going to have to go and do something else in
// the meantime either way, no?

    Short answer:  You are incorrect.

    Long answer: If you don't believe what people with experience with
these things are saying, do your own experimentation.  For best results,
you can find some disks that are exactly the same internally but only vary
with their interfaces.  Try different things that might happen in the real
world.  I'd suggest starting by getting two machines, four disks, and one
IDE controller, and one SCSI controller.  Build one machine on IDE and one
on SCSI.  Do stuff like copying data from one disk to the other, install a
database server (i.e. postgres) and do some benchmarks.  Do it again while
there's some activity on the other disk (i.e. build postgres) and see how
it does.  In fact, just run a make on each disk and see which system
finishes first.

// I've had the machine improperly shut down many many times for a
// variety of reasons. I've never restored a file from backup and I've
// never lost a file that I'm aware of. At least not that I can
// remember, if I did it couldn't have been very important because I
// didn't notice.

    *shrug* that's rare, then.

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