Re: ISCSI: Urgent Flag requirement violates TCP.

[Matt Wakeley <matt_wakeley@agilent.com>]

Glen Turner wrote:

> Matt Wakeley wrote:
> >
> > Nope.  Machines today using "off the shelf" stacks utilizing 1Gbps ethernet max out the CPU
> > running the TCP/IP stack, with no processing power left over for doing any work.  Machines
> > will not be able to fully utilize the new 10Gbps links if the TCP/IP processing is not
> > offloaded out of the main kernel.
>
> But that's an argument for iSCSI *not* using TCP services beyond the
> socket API.  To use such services the general purpose
> computer running TCP/IP offload would then need to change the
> code in the operating system *and* the code in the ethernet adapter.

Yeah, what's wrong with that? It sounds to me like you're saying "we can't make advances in speed
and technology because we have to change the OS".

>
>
> For commodity hardware you then need support from multiple
> manufacturers to get a computer that will run a complaint
> iSCSI client.  This is inviting maintenance issues (eg:
> need to install Windoze 2002 to fix security issue, but
> the driver for the particular ethernet card doesn't
> work with Win2002, and you can't just use any off-the-shelf
> TCP-offload card becuase you need iSCSI-socket support).
>
> I trying not to harp on about this, but it seems to me that
> people haven't thought out the software options at the client
> end in the same detail that they appear to have put into
> the target end.
>
> My feeling is that if the client can't use off-the-shelf
> gear then iSCSI is only going to displace Fiber Channel
> and will not become a widespread network service.  For
> example, ISPs attempting to add value to their service
> will need to find another mechanism to offer a storage
> and backup service to their customers, whereas iSCSI
> could be an ideal candidate for that application.
>
> Best regards,
> Glen