wayne@dsndata.uucp (Wayne Schlitt) (12/06/89)
i am looking to by another disc drive and i would like to know which will give you better performance, an HPIB disc drive (using a high-speed HPIB of course) or a SCSI disc? i believe that there are two types of SCSI controller cards: asynchronous and synchronous. from what i know a high speed HPIB has about 1meg/sec bandwidth, the async SCSI has 1.5meg/sec bandwidth and the sync SCSI has 4meg/sec bandwidth. will the synchronous SCSI really be that much faster? will the disc actually transmit data that quickly? can a HP9000/370 receive data that quickly? does anybody have a recommendation on a _fast_ disc that has >150meg. (preferably 300meg or so) -wayne
kinsell@hpfcdj.HP.COM (Dave Kinsell) (12/12/89)
>will the synchronous SCSI really be that much faster? will the disc >actually transmit data that quickly? can a HP9000/370 receive data >that quickly? The burst rate on the bus bus is negotiated between the mainframe and each individual peripheral. It is not uncommon for devices to be able so sustain 4 meg/sec on the bus, for as long as the peripheral has data in its buffer to transmit or room to receive. However, the average data rate to the media under ideal conditions is only about 1.5 meg/sec, with state-of-the-art 5.25" Winchesters. With a typical multi-user load, it is much less, due to all the random seeking required. Therefore, the actual gains observed with one sync SCSI disk on a bus may be minimal. If you have multiple disks and you're able to balance the load among them, then the higher bandwidth of SCSI can show real advantages. Exactly how much is highly workload dependent. I've seen 50% type of improvements, even when using slow disks. -Dave Kinsell use kinsell@hpfcmb.hp.com DISCLAIMER: Not an official policy statement of the Hewlett-Packard Company.
tonyc@hpurvmc.HP.COM ( Tony Cox (SR) ) (12/13/89)
You may want to use the SCSI daughter board in lieu of the DIO-1 board as it is a faster interface. I have been encouraging my customers to try to go to SCSI based devices as a large amount of peripherals such as optical and dat are going to be SCSI based. The part number for the SCSI daughter board is 98265A. tonyc