Re: Recomended FS - Mailing list pgsql-general

On Mon, 20 Oct 2003, Nick Burrett wrote:

> 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?
>
> The duty cycle of SCSI drives is 100%.  The duty cycle of IDE drives is
> around 30-40%.  Therefore one uses SCSI drives in mail and news servers
> where disk access is more-or-less permanent.  IDE drives usually degrade
> or fail faster under such load.
>
>  From experience I have noticed that IDE drives that initially perform
> at 30Mbyte/sec dropped to around 10Mbyte/sec after a year or so.
>
> >     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.
> >
> > IDE Hard Disk 40Gb 7200RPM   = 133Mbs = 50UKP
> > SCSI Hard Disk 36Gb 10000RPM = 160Mbs = 110UKP
>
> On new servers doing a software RAID1 sync between two disks, I find the
> following sustained transfer rates:
>
> SuperMicro 6013P-i ATA 133 80Gb IDE 7200rpm: 39000kbytes/sec.
> SuperMicro 6013P-8 SCSI 320 72Gb SCSI 10000rpm: 65000kbytes/sec.
>
> The IDE drives are on seperate busses.  The SCSI drives are on the same bus.
>
> I think that the 320Mhz SCSI busses are a bit faster than the 133Mhz ATA
> busses.
>
>
> >     Is that extra 27Mbs worth another IDE Disk. and while you can get
> > bigger faster SCSI disks prices go through the roof. Its no longer RAID
> > but RAED (Redundant Array of Expensive Disks)
> >
> >     My advise not that I've got any proof is that the money is better
> > spent on a good disk controller and many disks than on each disk.
> >
> >     In short if you have money to burn then by all means get SCSI but
> > most people are better of spending
>
> I suppose that's your choice.  Another way of looking that things is to
> consider the worth the server has to your business and factor that into
> how much you should consider spending on equipment.
>
> e.g. if the server can be attributed to £10,000/year, then perhaps a
> cheap PC will do.  If £1 million of your business relies on the server,
> then perhaps you should look into investing more into it.
>
>
    At last somone who has the real answers that I thought ought to be
true all the time. Its a shame nobody can give some hard and fast numbers
that I can get the budget people to understand!

Peter Childs