Hi
I have a linux box with a IBM Deskstar 75XP (one of the faster IDE HD's) on
ATA66 bus together with a Seagate X15 U160 SCSI HD on a Tekram SCSI Controller.
To get Linux on the scsi HD I had to first install it on the IDE HD (so I could
patch the kernel to support the SCSI Controller. The same system using SCSI is
*Much* faster than using IDE. This shows itsself in the kernel compile of 2.2.16
which takes 5 mins with linux running on the IDE drive and 3.5 mins on the SCSI
drive. (Using Athlon 1.1G.
The same is true in windows where copying a file between 2 partitions on scsi is
25% faster than copying a file between 2 partitions on the IDE drive (even with
the IDE drive on an ATA-100 bus - which made hardly any difference to
performance over connecting it to an ATA-66 bus!).
Having said that, in terms of capacity, the SCSI drive cost 4 times as much as
the IDE one, but is no where near 4 times the speed :-(
Sustained Transfer rates from my SCSI drive (i.e copying a 650MB ISO image to
another partition) totals some 39MBytes/sec while the IDE drive manages only
23MB/Sec.
Speed is not the only advantage of SCSI - for terminal expanders it works well
too, buy a drive, and plug it in - Modern scsi controllers sort out the SCSI ID
for you. None of this IDE business of connecting a CD-ROM drive to a channel,
and thus slowing down the HD to the same rate as the CD (though you cant mix non
ultra 2 or 3 stuff like this).
Also, 40 speed SCSI CDroms are more likely to be 40 speed cause the SCSI
controller its-self handles the data transfer leaving the processor to do more
important stuff.
The choice in DVD / CDROM /Writers for SCSI though is naff - with the faster,
more modern writers being IDE - I cant for example find a 12x10x32 CDwriter for
SCSI, the re-write is invarably only 4 times (but you need special (expensive)
cdrw disks to do more than 4x anyway).
DVD drives for a SCSI bus?? - You'll be lucky!
SCSI writers are top under linux though cause none of the hotch-botch IDE-SCSI
emulation is required. CD-writing with a SCSI HD or CD-ROM drive to a SCSI
writer is *really* reliable, and fast, and it works no matter how busy you make
your system during the copy.
SCSI, while a server solution (due to cost) is not crude like IDE, and makes for
a high performance (high expense) workstation. Though you need an IDE bus for a
cheap, massive IDE HD, and for an IDE DVD drive.
Nigel
