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

[Vladislav B. <vs...@vl...>]

Hi,

I'm afraid, I can hardly understand your problem. All you need in this mode are:

1. Create a forwarding target for each your real ("optimized") target on the active
side that is exporting the same SCST device and accepting redirected commands from the
non-optimized passive node. This target is NOT visible to initiators, hence its ALUA
state doesn't matter as soon as it is active.

2. Connect to this target from the passive node and use imported from it SCST device to
redirect all commands coming to the corresponding initiator-visible non-optimized
target. Use scst_disk for that device with CONFIG_SCST_FORWARD_MODE_PASS_THROUGH enabled.

Vlad

?波 史 wrote on 08/16/2017 12:48 AM:
> <https://outlook.live.com/owa/?path=/mail/AQMkADAwATNiZmYAZC1iZjJkLTEyZjItMDACLTAwCgAuAAAD19NTu8xoHkmNVIek5Mln7QEAMi7U5dfozk6Su7bNKKRg5wAAAMGV6PsAAAA%3D&realm=live.com>
> 
> 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.
> 
> 
> 
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