Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!brutus.cs.uiuc.edu!lll-winken!ncis.tis.llnl.gov!helios.ee.lbl.gov!pasteur!ucbvax!hplabs!hpfcso!hpfcdj!kinsell From: kinsell@hpfcdj.HP.COM (Dave Kinsell) Newsgroups: comp.sys.hp Subject: Re: HP-IB vs SCSI discs Message-ID: <17330007@hpfcdj.HP.COM> Date: 12 Dec 89 03:36:01 GMT References: Organization: Hewlett Packard -- Fort Collins, CO Lines: 27 >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.