RE: Towards Consensus on TCP Connections

[Stephen Byan <Stephen.Byan@quantum.com>]

Stephen Bailey [mailto:steph@cs.uchicago.edu] wrote:

> The gating factor for whether iSCSI succeeds is not going to be 200
> MB/s instead of 100 MB/s out of a single LUN.

In general, I agree. iSCSI can succeed in the high and midrange storage
market without link aggregation for a single LUN. These markets can afford
10 Gb/s links.

As a disk device level interface, iSCSI will not succeed unless it offers at
least 2 Gb/s by around 2002, at very low cost for the link. Note that even
Serial ATA starts at 1.5 Gb/s in 2001. Take a look at the Serial ATA speed
roadmap on slide 16 of Intel's Serial ATA presentation at WinHEC:
http://serialata.org/F9pp.pdf. 

One can argue the technical merits, but from a marketing viewpoint, the disk
industry (both suppliers and customers) has long held the view that
interface speeds need to match the media data rate. iSCSI can try to make an
argument that slower speeds are technically adequate, but this will increase
the barriers to establishing iSCSI as a device interface. 
 
> If iSCSI works at ALL in a cost effective way that can be implemented
> in a disk, there'll be wild dancing in the streets and you'll all (or
> maybe your companies will) be rich beyond the dreams of avarice.
> 
> The easier you can make it for the implementors, the more likely it
> will succeed.

Disk drive companies have implemented much more complex interfaces than
iSCSI and TCP - e.g. fibre channel arbitrated loop. And multiple TCP
connections don't look very hard to implement. They just look like a wart.
But I think a necessary one.

Regards,
-Steve

Steve Byan
<stephen.byan@quantum.com>
Design Engineer
MS 1-3/E23
333 South Street
Shrewsbury, MA 01545
(508)770-3414
fax: (508)770-2604