I think that the advantage of using SCSI drives is not only in the
transfer speed, which as you say is equal to one of your newer IDE
drives, but IDE uses more CPU DMA to run than using SCSI which frees
the CPU up from managing the data transfer. I don't know all the
details as I am not a technical guy (not too much anyway), but when
faced with limited CPU power, SCSI drives will always be better than
IDE from what I have read in the past.
This will speed up your G4 PowerMac, as it will have more CPU
resources to work on other tasks, instead of using a chunk of it's
power to transfer data over the IDE bus.
I have several ATTO fibre optic controller cards pulled from Avid
Meridian audio/video editing MDD G4 systems, if anyone is interested
in getting one. I think the max transfer speed for them is faster
than your 80MB/s, but then you need a hard drive or adapter that
converts drives to fibre optic, which I am unfamiliar with, as the
editing systems did not come with the storage drives that the fibre
optic cards connected to.
Not sure how you are going to test the speed improvement you can get
from using SCSI drives instead of IDE, when both drives are
transferring data at the same speed, but as I said above, your G4(s)
should have much more resources available when using SCSI than IDE.
On Nov 15, 2011, at 7:21 AM, Bruce Godfrey wrote:
dc, do you have any data on how much difference a fast SCSI drive
makes in a MDD or similar G$ Mac? I just installed one and I have
used Disk Speed Bench X to test the transfer speed. I find 80MB/
sec. My original IDE Hitachi Deskstar on the ATA100 bus is only
moving about 50MB/sec. However, another WD drive on the same ATA
100 bus is also moving 80MB/sec.
I was hoping the 15K U320 SCSI drive would easily beat a good IDE
drive, but that does not appear to be the case. Is it maybe the
kind of test Disk Speed Bench X performs?
Another related point - AFAIK the fastest SCSI card made for a PCI
slot is U160. The U320 cards are all PCI-X or later. Those work in
a PCI slot, but only at 33MHz and 32 bits. The PCI SCSI cards, at
least the ones from ATTO Tech, actually use the 64 bit wide PCI bus
in old Macs. Maybe the only PCI cards made that do.
Bruce
--
You received this message because you are a member of G-Group, a group for
those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs.
The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette
guide is at http://www.lowendmac.com/lists/netiquette.shtml
To post to this group, send email to g3-5-list@googlegroups.com
For more options, visit this group at http://groups.google.com/group/g3-5-list
