Re: SCSI or IDE
----- Original Message -----
From: Russell Coker <russell@coker.com.au>
To: Васил Колев <vasil@bastun.net>; <debian-isp@lists.debian.org>
Sent: Sunday, November 24, 2002 12:39 PM
Subject: Re: SCSI or IDE
> > You can put a lot more disks on a single SCSI
> > controler, than on a IDE controler, and there (afaik, i could be
> > mistaken) two drives on one bus cannot work simultaneously and share the
> > bandwidth (which isn't a problem with SCSI, if you have 160 MB/s bus,
> > and 3 disks that can make about 40MB/s, you can have all 120MB/s)
>
> 3ware IDE controllers support up to 12 drives. You won't find many SCSI
> controllers that can do that and deliver acceptable performance (you won't
> get good performance unless you have 64bit 66MHz PCI).
>
That is not true.
> Do a benchmark of two IDE drives on the one cable and you will discover
that
> the performance loss is not very significant.
>
> ATA-133 compared to Ultra2 SCSI at 160MB/s is not much difference. S-ATA
is
> coming out now and supports 150MB/s per drive.
>
Ultra2 can't do 160MB/s. Ultra2 is limited to 80MB/s. U160 (or ultra3) can
do 160MB/s. And perhaps, yes, Ultra2 vs ATA-133 might be comparable. And
U320 is now and can do 320MB/s....such is and has been the evolution of both
standards.
> > And maybe i should say something about the reliability, SCSI disks don't
> > die that often, compared to IDE drives, while being used a lot 24x7.
>
> The three biggest causes of data loss that I have seen are:
> 1) Incompetant administrators.
Amen.
> 2) Heat.
Halleluja, Brother!
> 3) SCSI termination.
>
Huh? I'd honestly have to say this falls into the same category as 1)
Incompetant administrators. Get the termination right and it all works just
fine, which is now easier than ever since controllers have been able to
autoterminate for many many years and now they are building terminators
right into the cable. And there are other factors like cable quality and
length. It's cerntaily more complicated but again, I feel it's worth it
once you know what you are doing.
> SCSI drives tend to have higher rotational speeds than IDE drives and thus
True, and in your first reply on this thread didn't you quote this as one of
the primary factors determining speed?
> produce more heat. Even when IBM was shipping thousands of broken IDE
hard
yes, fans are our friends!
> drives (and hundreds of broken SCSI drives which didn't seem to get any
> press) the data loss caused by defective drives was still far less than
any
> of those three factors.
Hmm, yeah, there's crap in both sectors that's for sure. I can't say I've
been a huge fan of IBM drives in the past.
vec
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