RE: iSCSI ERT: data SACK/replay buffer/"semi-transport"

["Dave Peterson" <dap@cisco.com>]

> -----Original Message-----
> From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of
> Stephen Bailey
> Sent: Monday, April 09, 2001 1:57 PM
> To: ips@ece.cmu.edu
> Subject: Re: iSCSI ERT: data SACK/replay buffer/"semi-transport"
>
>
> > Exactly, I've worked in this context (though its been some years now).
> > It was true (at one time) that tape had a tractability limit, e.g.,
> > a tape backup of a terabyte was out of the question.  Has that changed?
>
> I think this is precisely the point.  Existing, off-the-shelf SCSI
> solutions DO NOT presently solve this problem.  Both ||SCSI an FCP
> burp the operation on a expectable, O(days) failure rate.  The rate of
> adoption for the FCP-2 command recovery feature is overwhelming to the
> point that the tape guys have been talking about end-running the
> problem with explicitly addressed commands.
>

Not true. The reason for the explicit command set is a result of the
difficulties encountered when attempting to perform FC sequence-level
recovery in an out-of-order environment. The command set will also allow a
more robust tape command queuing implementation.

Dave