On Mon, 20 Oct 2003, Peter Childs wrote:
>
>
> On Mon, 20 Oct 2003, Shridhar Daithankar wrote:
> >
> > A fast HD with a good RAID controller. Subject to budget, SCSI are beter buy
> > than IDE. So does hardware SCSI RAID.
> >
> I hate asking this again. But WHY?
>
> What SCSI gain in spinning at 15000RPM and larger buffers. They
> lose in Space, and a slower bus. I would like to see some profe. Sorry.
SCSI beats IDE hands down for databases, and for one reason above all the
rest. They don't generally lie about fsync.
With SCSI, you can initiate 'pgbench -c 100 -t 1000000' and pull the plug
on your server, and voila, the whole thing will come back up (assuming a
journaling file system, and solid hardware.)
Do that with IDE with write cache enabled and you WILL have a scrambled
database that needs to be re-initdbed and restored.
Now, turn off the write cache on the IDE drive, which will make it solid
and reliable like the SCSI drive, and compare speed, it's not even close.
Until the IDE drive manufacturers start making IDE drives that actually
report fsync properly, they're a toy that should not be used for your
database unless you know the dangers they present.