Re: Target Reset

["Eddy Quicksall" <ESQuicksall@hotmail.com>]

I think the point is whether or not you should support a TARGET RESET, not
whether or not your system should issue it.

On systems like you mention, you should probably not do a TARGET RESET.

On NT MSCS, you could probably do a LOGICAL UNIT RESET for all known
devices. Since the driver doesn't know which device is the quorum device, it
would have to reset all known devices.

Eddy
----- Original Message -----
From: "John Hufferd" <hufferd@us.ibm.com>
To: "Eddy Quicksall" <ESQuicksall@hotmail.com>
Cc: <ips@ece.cmu.edu>
Sent: Monday, April 23, 2001 5:11 PM
Subject: Re: Target Reset


>
> Eddy,
> All that might be true of NT, but the Shark, and Symmetrix have many other
> clusters and non clusters connected to it.  The shark for example has 32
> different SCSI connections.  A target reset will effect every one, not
just
> a specific NT cluster.
>
> .
> .
> .
> John L. Hufferd
> Senior Technical Staff Member (STSM)
> IBM/SSG San Jose Ca
> (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
> Internet address: hufferd@us.ibm.com
>
>
> "Eddy Quicksall" <ESQuicksall@hotmail.com> on 04/23/2001 02:02:33 PM
>
> To:   John Hufferd/San Jose/IBM@IBMUS
> cc:   <ips@ece.cmu.edu>
> Subject:  Re: Target Reset
>
>
>
> Actually, I made an assumption but did not make a suggestion; I only
wanted
> to bring up the point that there has to be some way to emulate what NT is
> doing and at this time.
>
> On the current NT MSCS, there will only be 2 hosts on the target. I have
> heard that they have a multi-node cluster but I don't know how they do a
> challenge there (I suspect that they don't use RESET).
>
> Regarding the number of LUs, NT it is limited to a small number of LUs on
a
> target and a small number of targets on a bus.
>
> Eddy
>
> ----- Original Message -----
> From: "John Hufferd" <hufferd@us.ibm.com>
> To: "Eddy Quicksall" <ESQuicksall@hotmail.com>
> Cc: <ips@ece.cmu.edu>
> Sent: Monday, April 23, 2001 4:07 PM
> Subject: Re: Target Reset
>
>
> >
> > Eddy,
> > A target like an IBM Shark or EMC Symmetrix will have thousands of LUs
> and
> > 10s to 100s of Hosts connected to it, and you want to reset the whole
> > Target?  I do not think that is a good idea.  Perhaps Task Reset or LU
> > reset etc. but not Target Reset.
> >
> > .
> > .
> > .
> > John L. Hufferd
> > Senior Technical Staff Member (STSM)
> > IBM/SSG San Jose Ca
> > (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
> > Internet address: hufferd@us.ibm.com
> >
> >
> > "Eddy Quicksall" <ESQuicksall@hotmail.com> on 04/23/2001 09:44:05 AM
> >
> > To:   "Dillard, David" <david_dillard@adaptec.com>, John Hufferd/San
> >       Jose/IBM@IBMUS
> > cc:   <ips@ece.cmu.edu>
> > Subject:  Re: Target Reset
> >
> >
> >
> > I am wondering how clustering will work on NT without some sort of
reset.
> >
> > On parallel SCSI, NT will issue a SCSI BUS RESET to break reservations
> > during a challenge for the quorum drive.
> >
> > On iSCSI, there is no full equivalent to the SCSI BUS RESET so I would
> > assume the NT driver would have to issue a TARGET RESET to each target
> that
> > it is supporting.
> >
> > How would you propose this would be done without a TARGET RESET?
> >
> > Eddy
> >
> > ----- Original Message -----
> > From: "John Hufferd" <hufferd@us.ibm.com>
> > To: "Dillard, David" <david_dillard@adaptec.com>
> > Cc: <ips@ece.cmu.edu>
> > Sent: Sunday, April 22, 2001 3:20 PM
> > Subject: RE: Target Reset
> >
> >
> > >
> > > This is at least better.  But I do not have the issue of it being
> vendor
> > > unique.  This is a shut down and restart of the complete Target, and
> will
> > > probably be part of the vendors' operator console or their own remote
> > > support functions, it is not clear that it needs to be a general
> > management
> > > function that works the same on all iSCSI Storage Controllers.
> > >
> > > Many of the major Storage Controller do not support this feature
today.
> > >
> > > I do not believe that most SNMP implementations are very secure.  Most
> > > folks do not want to have a changeable MIB until they have secure
SNMP,
> > and
> > > even though there is a version of SNMP that has security features,
this
> > has
> > > not been well supported.
> > >
> > > I do NOT think that Target Reset should be in the base iSCSI protocol,
> > but
> > > I think it is reasonable to hold this discussion apart from the base
> > > protocol document, and the question should be asked if this is a
> general
> > > management function or a vendor specific console or remote support
> > > function.
> > >
> > >
> > >
> > > .
> > > .
> > > .
> > > John L. Hufferd
> > > Senior Technical Staff Member (STSM)
> > > IBM/SSG San Jose Ca
> > > (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
> > > Internet address: hufferd@us.ibm.com
> > >
> > >
> > > "Dillard, David" <david_dillard@adaptec.com>@ece.cmu.edu on 04/22/2001
> > > 08:13:49 AM
> > >
> > > Sent by:  owner-ips@ece.cmu.edu
> > >
> > >
> > > To:   ips@ece.cmu.edu
> > > cc:
> > > Subject:  RE: Target Reset
> > >
> > >
> > >
> > > John,
> > >
> > > I understand the danger of issuing a target reset and I agree that it
> > > should
> > > not be a part of the an initiator's normal error recovery procedure.
> > > However, looking at this from a management perspective I'd like to see
> a
> > > standardized way of resetting a target.  I don't want to see a variety
> of
> > > vendor unique methods of resetting targets sprout up.
> > >
> > > If resetting a target using the protocol is not desirable from your
> > > perspective would incorporating this feature into the MIB be
> acceptable?
> > > (MIBs are for management after all)
> > >
> > > ----------------------------------------------------------------
> > > David Dillard                          david_dillard@adaptec.com
> > > Management Software Group
> > > Adaptec, Inc.                          www.adaptec.com
> > >
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: John Hufferd [mailto:hufferd@us.ibm.com]
> > > Sent: Sunday, April 22, 2001 4:59 AM
> > > To: ips@ece.cmu.edu
> > > Subject: Target Reset
> > >
> > >
> > > I thought we had a number of discussion previously about Target Reset
> > (Warm
> > > or Cold).  I thought there was general feeling that this command is so
> > > dangerous that it should not be supported by iSCSI.  The long distance
> > > capability of iSCSI makes the risks involved unmanageable.  There
> should
> > > only be an Admin way to do this.
> > >
> > > Some folks have said that we could permit it and have special
> > authorization
> > > etc.  This would probably cause a separate section in the spec. to
> define
> > > the authorization approach,  and what ever other security is needed to
> > > prevent this from inappropriately being used.  All for what purpose?
> > This
> > > can not be part of error recovery from a normal initiator.  The wide
> > spread
> > > effect is too great for that.
> > >
> > > I would like to hear from the list about their feeling on this item.
> > >
> > >
> > >
> > > .
> > > .
> > > .
> > > John L. Hufferd
> > > Senior Technical Staff Member (STSM)
> > > IBM/SSG San Jose Ca
> > > (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
> > > Internet address: hufferd@us.ibm.com
> > >
> > >
> > >
> > >
> >
> >
> >
> >
>
>
>
>