Re: iSCSI: error recovery striation for rev08 (Was: iSCSI - open issues - no discussion - recovery levels)

[Sandeep Joshi <sandeepj@research.bell-labs.com>]

Mallikarjun,

My vote would be for two levels only.

If its bad weather(transport), you turn on maximum error recovery.
If its good weather, you live with session recovery.
Anything in-between may complicate implementations which
wish to isolate logic paths.

Since you wish to suggest a better division, let me add that
a new scheme for dividing recovery levels would need to be
backed up by potential usage scenarios.  
e.g. if you are doing tape backup, use level A
     if this is within-enterprise access, use level B
     if this is <something..something>, use level C

IMHO, more than two levels would make good sense only if there
were some good real-world scenarios to exploit them.  Otherwise
it may just end up as a case of over-engineering.

-Sandeep
 

"Mallikarjun C." wrote:
> 
> >- on the recovery there is consesus that it is a good idea; there is no
> >consensus on how many layers to enforce (I think that 2 - all or nothing is
> >a good choice).
> 
> I am sure Julian is trying to kick off a discussion here, after
> collaborating with me on the London proposals  :-)
> 
> Seriously, Julian and I were both hoping for more comments before
> rev08 in this area - which I haven't seen too many of.
> 
> Let me state for the record (as I already said in London) that
> all-or-nothing is not to my favor - IMHO, that erects a too steep
> barrier between the two levels.
> 
> I however can see the case for considering decreasing the number
> of levels.  Allow me sometime for cogitation on this once rev08
> is published.  I hope to post an alternative scheme of striation
> by the end of next week for WG consideration.  For rev08, current
> plan is to capture what was presented in London, but state clearly
> that this area is still under debate.
> 
> Thanks.
> --
> Mallikarjun
> 
> Mallikarjun Chadalapaka
> Networked Storage Architecture
> Network Storage Solutions Organization
> MS 5668 Hewlett-Packard, Roseville.
> cbm@rose.hp.com
> 
> >Dear colleagues,
> >
> >Considering that the next plugfest is getting close and we would like to
> >have
> >version 08 ready for it.
> >
> >We have two open items that got little attention on the list up to now:
> >
> >- taking out the markers and inserting a reference to an external framing
> >draft (what is mandatory, what is optional etc.)
> >- recovery the recovery levels proposal
> >
> >The status  with both is as follows:
> >
> >- on the framing there is consensus that it is a good idea; there is no
> >consensus on what is  MUST, SHOULD etc.
> >- on the recovery there is consesus that it is a good idea; there is no
> >consensus on how many layers to enforce (I think that 2 - all or nothing is
> >a good choice).
> >
> >Regards,
> >Julo
> >
> >
> >