Problem recently reported by NetApp when an iSCSI target has multiple IP's
Created attachment 325891 [details] Add checks for <TargetName, ISID, TargetPortGroupTag> The enclosed patch fixes the problem. In iSCSI world a session encapsulates an Initiator-Target Nexus. The current inbox RHEL5.x driver uses the iSCSI TargetName (hence the <iSCSITargetName, iSCSIInitiatorName> tuple) to uniquely identify an iSCSI Session. This is however insufficient, when a Target Node (identified by an iSCSIName) can be accessed via multiple portals (identified by an IP Address or DNS assigned TargetHostName, tcp port#, portal group tag). This is the problem with the NetApp. Configuration. || Port A (IP1/DNS Name) || Port B (IP2 or DNS Name) || || +---------------------------------------------+ | | | +------------------------------------+ | | | NetApp.Target (unique iSCSIName) | | | +------------------------------------+ | +---------------------------------------------+ As per spec., each iSCSI Session is uniquely identified by the 4-tuple <initiator Name, TargetName, ISID, TargetPortGroupTag>. Since InitiatorName is a constant in our case this reduces to a 3-tuple <TargetName, ISID, TargetPortGroupTag> Remember that the ISID effectively encapsulates Target IP (or DNS assigned Target Host Name) and the TCP Port the target is listening on. The fix essentially checks for <TargetName, ISID, TargetPortGroupTag> instead of just the TargetName.
Marcus, This is a very critical bug reported by NetApp. I would appreciate if you can help get this into RHEL5.3. -david S.
Created attachment 325897 [details] patch with version correction Updated the version number to indicate 1st patch for 5.3 version of this driver. Now: 5.01.00.01.05.03-k9
The inability to uniquely identify an iSCSI session is a major limitation of the current inbox RHEL 5.3 driver. Without this feature, the driver is potentially dangerous as it could lead data unavailability/corruption as seen in our tests at NetApp. I strongly feel this patch which incorporates the above feature should be included for RHEL 5.3.
Tom - patch freeze for snap 6 is TODAY. Will this make it, and does it qualify?
in kernel-2.6.18-126.el5 You can download this test kernel from http://people.redhat.com/dzickus/el5
The reported iscsi session identification problem is resolved with iscsi tuple usage. I verified it on provided 2.6.18-126.el5 kernel, Now we can have more than one paths to same lun. Thank you.
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2009-0225.html