liam@cs.qmw.ac.uk (William Roberts) (04/06/90)
In article <AUXPOST%90040422380113@PUCC.BITNET> MATLEVAN@EKU.BITNET (Jerry LeVan) writes: >timex dd if=/dev/rdsk/<whole disk> of=/dev/null bs=12k count=1024 > >The above times a 12 meg transfer from the raw disk to the null device >Some of the times I obtained are: > >Apple 160 MB disk 44.08 secs .2727 MB/Sec >Apple 80 MB disk 58.23 secs .2060 MB/Sec > >At&T 3b2/1000-70 330 MB disk 20.24 secs .5928 MB/Sec >DecStation 3100 330 MB disk 29.8 secs 026 MB/Sec Sun 3/50 with SCSI 141M disk 35 secs SunOS 3.5 Sun 3/60 with SCSI 141M disk 30 secs SunOS 4.0 SparcStation1 SCSI 327M disk 33 secs Sequent B21000 377M Eagle 25 secs Sequent B21000 795M Swallow5 23 secs > >Do you think the above test (cribbed from a trade journal) gives >a reasonable estimate of relative disk performance? Ought to be OK - you'd get better actual performance out of using larger block sizes (e.g. 60k or so). It looks to be a little bit OS dependent, judging from the Sun 3/50 to Sun 3/60 figures, and it also probably varies according to machine load. But I'd go for it as a broad comparison. >Some SCSI accelerator's are starting to appear on the market. >(Daystar and Surfboard?) Has anybody had any experience with >these type of devices? I tried the Maccelerate card from NatSemi - ran OK under 1.1.1 but we had compatibility problems with some drives and NatSemi have apparently decided that it is not for retail sale any more (i.e. it works well if you know what you are doing, so OEMs and developers can build it into systems if they want). The main problem is that such products are mostly trying to second guess what MacOS disk drivers are going to do, and the MacOS SCSI manager (prior to System 7) does so little that there is complete anarchy! This isn't true under A/UX, but the manufacturers haven't worried that much about the A.UX market, and I'd guess that the IIfx product will kill off any interest that they had... ><Sigh> I really broke down and had a >good cry when if found out that Apple was going to have a >MacII - Mac fx board swap for less than I paid for the DayStar >accelerator :-( I'll bet DayStar weren't over the moon either. -- William Roberts ARPA: liam@cs.qmw.ac.uk Queen Mary & Westfield College UUCP: liam@qmw-cs.UUCP Mile End Road AppleLink: UK0087 LONDON, E1 4NS, UK Tel: 01-975 5250 (Fax: 01-980 6533)