[Scst-devel] Active/Non-Optimized ALUA error, lost target port group id on Non-Optimized node disk

[?波 史 <in...@li...>]

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hello:

For alua(Active - NonOptimized) setup with latest scst code,  we config it with the mothod you pushed on Jun 7(commit msg: scst: update ALUA documentation (Active/Non-Optimized)), and map device from active node to nonoptimized node through iscsi without target group, but dont get expected result. On nonoptimized node, the mapped disks dont have target port group id info (get scsi inquiry 0x83 vpd via sg_inq cmd),so the host multipath cannot get the right NonOptimized disk info in pass-through mode(use scst_disk handler, enable target forwarding and CONFIG_SCST_FORWARD_MODE_PASS_THROUGH).

This problem is caused by the internal device map from active node to NonOptimized node. We have two methods for this(not tried):
1.  map the device from active to standby node through the target group for host, the mapped disks should have right target port group info on nonoptimized node. This method need to create a lot of different internal iscsi targets equal to the number of target groups, and may map one device to NonOptimized several times.
2.  modify the scst_disk handler code, get the target port group info locally and insert it to inquiry cmd(pass-through) response data, as the both two nodes have all same target groups.

Is there any other better way for this?
Thanks very much!

our scst configuration is like this：

node1 device group：
    scst device: disk1 (scst_vdisk)
         target group: tg1, active
            fc target: fc1     (local, lun1)
        target group: tg2, nonoptimized
           fc target: fc2    (peer, not real)

node2 device group:
    scst device: H:C:I:L (scst_disk)
        target group: tg1, active
            fc target: fc1    (peer, not real)
        target group: tg2, nonoptimized
            fc target: fc2     (local, lun1)

note: H:C:I:L is mapped from node1 disk1 via internal iscsi target.