So, TECHNICALLY speaking a Quadra 840AV with a nubus SCSI card (yea, I know, dreaming here) at 160MB/Sec will run the same as a Dual G5 with a SCSI 160 MB/Sec card. That is a theoretical throughput too. The machine still has to be fast enough to accept the data too. So your Quadra will still be limiting the amount of data it gets from the SCSI bus. But with SCSI, it can xfer files between drives without need of the CPU to manage it, so it can go full bore here. IDE has to use the CPU for everything. So it loads the machine down more. BUT, with machines so fast now, it is much less noticeable.
The older 50 pin SCSI is 8bit, SCSI1 and SCSI2. Speeds up to 10 MB/Sec with SCSI2, 5MB/Sec with SCSI1.
The new 68 (Wide SCSI) and 80 pin (SCA) SCSI you see speeds of 20 MB/Sec up to 320 MB/Sec. And you can double that easily by striping drives on the same controller. Like the new SCSI 320 cards from Adaptec and others, you can run striped arrays and get 640 MB/Sec. That is over a half a gigabyte a second!
A trick to do for speed vs cost is to get a SCSI controller card and a IDE drive and a SCSI to IDE converter, so the computer interprets the drive as a SCSI and the CPU of the computer only needs to communicate with the SCSI Controller. But the cost of the converters can negate a lot of the cost of the drives.
http://www.finitesystems.com/PRODUCT/san/scsi/scsiprimer.htm
http://www.seagate.com/support/kb/disc/tp/scsiu_buzz.html
I can't seem to find it, but I have read in print that the Mac Plus (with its SCSI1 DB25) can support up to 2TB of storage. Considering the speed of SCSI1, I can understand by it is not made anymore. 5 MB/Sec to fill a 2 TB HD. Hmm, how many YEARS do you have to wait?
I have seen SCSI2 to SCSI3 (50 pin to 68 pin) adapters.
So far nothing I can find specifies a practical limit to SCSI2 (50 pin narrow).
<>< <>< <>< <>< <>< <>< 73's Tom N�DIH
On Jan 23, 2005, at 4:50 PM, Steve Haybeck wrote:
Wont bus speed limit the adapter card speed? Serial transmition versus parallel. Better built? Still like SCSI. I had an old quadra that worked well with just a 500 MB scsi drive. Speed is relative. Would still like to find out what the real max size of a low profile 50 pin scsi hard drive is.
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