[rescue] Total corporate madness (

Joshua Snyder josh at imagestream.com
Wed Aug 6 15:47:10 CDT 2003

On Wed, 6 Aug 2003, Charles Shannon Hendrix wrote:
> I think they've gradually been trying to SCSI-ize IDE for years.

I agree totally.

> No, not really.  It's still very ATA. For one thing, I believe you can
> only have one drive per wire.
> Might be a good thing really, since from what I have noticed, an IDE
> drive dying usually takes the bus with it.  So, if you want reliable IDE
> raid, you need to stick to a single drive per controller.
> The exception I suppose is special raid controllers which (hopefully)
> don't allow any one drive to lock up the bus.

If your saying that it's still very much ide because it only supports one
drive per connection your not going to like Serial SCSI.  Serial SCSI is
point to point (one drive per connection) just like Sata.  Now I did
some looking around because I remember seeing stuff about Serial SCSI
drives having two ports.  It turns out that they do have two ports but it
is not to daisy chain the drives together.  It's to allow multi-path
communications with the drives, that way you can have two controllers in a
system and if one of them fails you can still talk to your drives.  Now if
your saying "It's still very ATA" because it is 100% compatible with ATA I
will give you that.

I have seen SCSI drives lockup a SCSI bus before.  In fact if you look at
the data-sheets about Serial SCSI that is the reason they give for having a
point to point connection between the drive and the controller.  I think I
have a good grasp of the differences between Serial SCSI and Sata...

150Meg/sec Half Duplex
1m Internal Cables
Single Port
Single host

SAS (Serial Attached SCSI)
300Meg/sec Full Duplex
>6m cables
128 devices per expander (16K devices per domain )
Dual Port
Wide port support ( two or more ports can be bonded together ) Looks like
this is intended to be used to connect the host adapter to an expander.
Muilt-host support
Sata compatible

So overall Serial SCSI is much nicer than Sata but Sata is not bad when
your talking about small to mid-sized setups in one computer chassis.


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