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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: iscsi : target port definitionEddy, That certainly fits within the scope of what I described. However, I don't think that's the "main purpose". As I understand it, the whole notion of target portal group was suggested to enable HW implementations with multiple iSCSI HBAs that (a) had multiple network interfaces/nics (b) could coordinate sessions across the network interfaces *within their own HBA* but (c) didn't have an additional (complex) software layer that could coordinate sessions across HBAs. In that case, we wanted a simple way to describe to the initiator (in SendTargets), that even though this target may have 4 ipaddress/tcpports available, they only work in pairs (say) as far as multi-connection sessions (one pair of addresses per HBA). That information would help the initiator from generating a lot of failed "add this connection to existing session" requests. This model turned out to have additional value in the SCSI modeling, so we took advantage of it. Jim Hafner "Eddy Quicksall" <eddy_quicksall@ivivity.com>@ece.cmu.edu on 09/14/2001 09:50:33 am Please respond to <eddy_quicksall@ivivity.com> Sent by: owner-ips@ece.cmu.edu To: "'Santosh Rao'" <santoshr@cup.hp.com>, "'IPS Reflector'" <ips@ece.cmu.edu> cc: Subject: RE: iscsi : target port definition They way I see it is the Target Portal Group is a way for target administrators to logically group things so the initiator knows which addresses:ports to use when establishing a nexus. Isn't that the main purpose? Eddy -----Original Message----- From: Santosh Rao [mailto:santoshr@cup.hp.com] Sent: Thursday, September 13, 2001 8:38 PM To: IPS Reflector Subject: iscsi : target port definition Hello, I have a question on the interpretation of the iscsi target port definition. The iscsi rev 08 defines the iscsi target port to map to an iscsi target portal group. Thus, any iscsi target that wishes to allow multiple SCSI paths to be established to the target node MUST provide at least 2 iscsi target portal groups. The above definition of an iscsi target port somewhat alters the semantics of a target portal group. A target portal group, by definition, is a collection of a set of network portals within the target across which a session can be spanned. Thus, if a target supports a multi-connection session spanning across all its network portals, such a target would use a single target portal group to indicate that 1 big fat session pipe could be established to all its network portals. This, in turn, would have the side effect of only providing 1 scsi path to the upper layer wedge drivers, if the iscsi initiators establish a session per target portal group. [which is the target port]. From an initiator's perspective, what should be the target side end-point of an initiator's sessions when it may need to support upper layer wedge drivers ? Should the initiator establish a session per target portal group [, in which case the above issue exists] ? Or, should it establish a session per TargetAddress ?? Regards, Santosh
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