Path: utzoo!attcan!uunet!husc6!bbn!rochester!cornell!uw-beaver!tektronix!tekcrl!terryl
From: terryl@tekcrl.TEK.COM
Newsgroups: comp.unix.wizards
Subject: Re: Vax 11/780 performance vs Sun 4/280 performance
Message-ID: <2736@tekcrl.TEK.COM>
Date: 14 Jun 88 16:54:29 GMT
References: <22957@bu-cs.BU.EDU> <14968@brl-adm.ARPA> <601@modular.UUCP> <7331@swan.ulowell.edu> <2282@rpp386.UUCP> <6926@cit-vax.Caltech.Edu>
Reply-To: terryl@tekcrl.tek.com
Organization: Tektronix, Inc., Beaverton,  OR.
Lines: 40

In article <6926@cit-vax.Caltech.Edu> mangler@cit-vax.Caltech.Edu (Don Speck) writes:
>And as Barry Shein said, "An IBM mainframe is an awesome thing...".
>One weekend, noticing the 4341 spinning a pair of GCR drives at over
>half their rated 275 ips, I was shocked to learn that it was reading
>the disk file-by-file, not track at a time.  BSD filesystems just
>can't compare to what this 2-MIPS machine could do with apparent ease.
>
>How do they get that kind of throughput?  I refuse to believe that it's
>all hardware.  Mainframe disks rotate at 3600 RPM like everybody else's
>and their 3 MB/s transfer rate is only slightly higher than a SuperEagle.
>A 2-MIPS CPU would be inadequate to run a BSD filesystem at those speeds,
>so obviously their software overhead is a lot lower, while at the same
>time wasting no disk time.  What is VM doing efficiently that Unix does
>inefficiently?


     Well, it might be partially due to hardware. Remember the dedicated
I/O channels the 360-370 systems have??? Do the 4341's have anything
similar???? Similar to CDC Cyber's peripheral(sp?) processors. Tape
drives on a Cyber are capable of blindingly fast things, but then, I've
seen a tape drive on a Cyber that could read a tape faster than ANY tape
drive could rewind under UNIX (caveat: I'm talking mainly DEC tape drives
here).

     Also, reading file by file; to quote a good joke from many moons
ago: "That man must be a lawyer. The information he gave is 100% accurate,
but totally useless." We need a little (actually quite a lot) more infor-
mation before we can say anything. What's the layout of the file on the
disk??? What type of file is it??? Is it extent-based, or something
different. If it's extent-based, what are the sizes of the extents???
Is there really a file system on the disk in question, or is it just that
one file???? etc.....


Boy
Do
I
Hate
Inews
!!!!