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- Newsgroups: comp.os.os2.misc
- Path: sparky!uunet!elroy.jpl.nasa.gov!swrinde!cs.utexas.edu!zaphod.mps.ohio-state.edu!n8emr!elektro!charlie
- From: charlie@elektro.cmhnet.org (Charlie Smith)
- Subject: Re: Disk Tansfer speeds, VLB, ISA bus saturation and max performance.
- Message-ID: <1992Dec14.135933.1394@elektro.cmhnet.org>
- Organization: Why do you suspect that?
- References: <1992Dec7.091529.3727@doug.cae.wisc.edu>
- Distribution: usa
- Date: Mon, 14 Dec 92 13:59:33 GMT
- Lines: 47
-
- In article <1992Dec7.091529.3727@doug.cae.wisc.edu> keiths@cae.wisc.edu (Keith Scidmore) writes:
- >What point is there in worrying about VLB when your average disk drive can't
- >come close to saturating the 8 MHz ISA bus? The majority of drives sold with
- >PCs these days are only capable of about 1 MB/s transfers anyway. If you
- >want to speed up your drives I don't see how putting your 8-bit IDE interface
- >on a 32-bit VLB is going to help you much unless you want to spend a ton
- >of money and buy four drives and have some interface that supports disk
- >striping.
-
- Are you mixing up your megabits and megabytes? Your run of the mill ESDI
- drive is 10 MBits/sec and will support an "effective" transfer rate around
- 800 KBytes/sec. Larger ESDI drives have a 15 MBits/sec transfer rate, and
- will support an effective transfer rate of up to about 1200 KBytes/sec.
- I'm using Maxstor XT-8760-E's with UNIX, and the numbers are similar. The
- 8760 is a 650 MByte drive with 52 sectors / track, and that's a 15 MBit/sec
- instantaneous rate. SCSI is a better way to go, but I've got a lot of $$
- in ESDI. BTW, the controller you use can make a lot of difference.
-
- Actually, in a multitasking environment like UNIX or os/2, SCSI is much
- better if your operating system is smart enough to do things like have
- actuators moving on multiple drives at the same time. I don't know about
- IDE, but MFM, RLL, and ESDI won't support that.
-
- >
- >Unless you want a file server or a fast network interface, ISA/IDE is more than
- >adiquate for your drives. The main advantage of VLB is to give the
- >video card a very high speed access port. VLB also invites future
- >alternatives to ISA and EISA such as a means to implement a very fast
- >SCSI-II interface. I think these cards will be available in the very
- >near future.
- >
- >My solution is to buy a 520 MB IDE Fujitsu drive that runs at 2.5 - 3 MB/s
- >and run it on ISA with a 2 MB (the maximum under OS/2) memory cache. I
- >don't think you can do much better than this for drive access on a
- >stand-alone system.
- >
- >... or am I missing something?
- >
- >
- >Keith R. Scidmore
-
-
- Charlie Smith charlie@elektro.cmhnet.org csmith@dsac.dla.mil whois ces10
- Eves: 614-471-1418 Days: 614-692-9064 FAX: 614-692-8217
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- Columbus Ohio USA
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