Re: [Ips] iSCSI-specific unit attention conditions
"Bill Galloway" <BillG@breatech.com> Sat, 04 April 2009 06:28 UTC
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From: Bill Galloway <BillG@breatech.com>
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Date: Sat, 04 Apr 2009 01:29:03 -0500
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Subject: Re: [Ips] iSCSI-specific unit attention conditions
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This is a re-send from a different email.... I am the guilty party associated with these sense codes. I have been traveling for the last few days or I would have chimed in sooner. My original proposal was not iSCSI specific. It added three ASC/ASCQs which were DEVICE PORT ADDRESS ADDED/CHANGED/REMOVED. The original names actually explain the intent better (IMHO). We produce an iSCSI target with many "Portal Groups" and "Network Portals". Portal Groups come and go dynamically. Within a Portal Group, Network Portals come, go, or change dynamically. The intent is for the initiator to be connected to all Network Portals, on all Portal Groups, all of the time. This is usually accomplished with some combination of MCS in the initiator and a MPIO (multipath) layer above the initiator. The initiator is perfectly willing to make all of these connections but there is no way specified in any standard to accomplish this task. There is a mix of layers here that makes for a messy solution. I am certainly open to a better one. The SCSI layer could care less about Network Portals coming, going, or changing but something has to kick the initiator to do a new discovery and make the appropriate connections. This would have been better handled at the iSCSI layer but I could find nothing available. In our implementation the MPIO layer traps these UAs and kicks the initiator. The SCSI layer does have a legitimate need to know about Portal Groups coming and going. These map to SAM target ports and the SCSI layer may need to know. The initiator also needs to know so that it can make the new connections. In our implementation the MPIO layer also traps these UAs and kicks the initiator. Why three codes? No good reason. My first proposal was more generic than iSCSI and there was a hope that it would be useful to other protocols. To get the proposal passed, I agreed to change the names to be iSCSI specific. In retrospect when I made the name change, I could have dropped it to one code. In our current implementation we treat all codes the same. I hope this explains the rational for these ASC/ASCQs. I am not aware of anything in the iSCSI spec that accomplishes these goals. I am certainly willing to explain further and to work with STORM to document this better and/or come up with a better solution. Bill Galloway Pivot3, Inc. BillG[-at-]Pivot3.com
- [Ips] iSCSI-specific unit attention conditions Black_David
- Re: [Ips] iSCSI-specific unit attention conditions Paul Koning
- Re: [Ips] iSCSI-specific unit attention conditions Black_David
- Re: [Ips] iSCSI-specific unit attention conditions Paul Koning
- Re: [Ips] iSCSI-specific unit attention conditions Paul Koning
- Re: [Ips] iSCSI-specific unit attention conditions brown_David1
- Re: [Ips] iSCSI-specific unit attention conditions Knight, Frederick
- Re: [Ips] iSCSI-specific unit attention conditions Knight, Frederick
- Re: [Ips] iSCSI-specific unit attention conditions dcuddihy
- Re: [Ips] iSCSI-specific unit attention conditions Paul Koning
- Re: [Ips] iSCSI-specific unit attention conditions Knight, Frederick
- Re: [Ips] iSCSI-specific unit attention conditions Kevin_Marks
- Re: [Ips] iSCSI-specific unit attention conditions Black_David
- Re: [Ips] iSCSI-specific unit attention conditions Bill Galloway
- Re: [Ips] iSCSI-specific unit attention conditions Julian Satran
- Re: [Ips] iSCSI-specific unit attention conditions Ralph Weber