🚀 go-pugleaf

see.my.sig.4.addr@no.damn.spam.com wrote:
> 
> On Sun, 30 Nov 1997 13:55:25 GMT, bob@lintilla.demon.co.uk (Bob
> Cousins) wrote:
> 
> >In demon.tech.pc, Zypher wrote:
> >
> >>UltraDMA (the latest standard-forget EIDE also known as Ultra ATA or Ultra
> >>33) can give a 33mb/sec transfer rate...but in real life its about
> >>20mb/sec-not bad.
> >>
> >>If you want real speed-go with Ultrawide AV SCSI or higher like I have
> >>(true 40mb/sec contionous, used for video capture, servers and the like)
> >
> >It's funny how people with SCSI systems often seek to put down EIDE, and at the
> >same time make ridiculous performance claims for SCSI. Maybe its because they
> >have paid twice as much for their disk storage, and feel a need to justify its
> >cost, even if by inventing performance figures?
> >
> >If the Seagate Cheetah can do 14-21 MB/sec, I doubt you are seeing continuous
> >40MB/sec. The fact is in a typical workstation, SCSI offers little or no benefit
> >to the overall performance of the system. If you don't believe me, see
> >http://www8.zdnet.com/pcmag/pclabs/report/r960702a.htm.
> 
> With a single HDD running a single app, sure EIDE is going to be the
> same.  The difference is that SCSI is multithreading.  Where you see a
> big performance boost is while multitasking, especially with multiple
> drives, or a RAID controller.
> If you only have one HDD you really don't care how wide the data path
> is for anything but that cheetah.  Sustained transfer rates (which is
> the only thing that counts on single drive systems) are only around
> 10mb/sec for most drives.

I don't think mutli-threading will make much of a difference with SCSI
on a single disk. Since, the disk seems to be the limiting factor for
sustained transfer not the protocol.  Although, I guess in a situation
where one request is for something that isn't in the disk buffer and a
request from another thread for something that is in the buffer.  SCSI
will allow the request for data in the buffer to occur even while the
disk is seeking and reading the first request into the buffer. (Just a
guess though).  The biggest advantage of SCSI though is definitely with
multiple devices whether that is a hard disk, raid, CDROM, DVD, or any
other SCSI device.  Another thought though... Would the burst tranfers
rate have a larger affect on Virtual memory operations?

Don