[stgt] tgtd regression: new NAA descriptor breaks multipathd

[Eric Millbrandt]

Hello all,

Since commit 6402eb875488240a403c6d032b9e81d7802801eb "add NAA Locally
Assigned designator to 0x83 VPD page" added generated NAA descriptors,
the scsi_id field that I was assigning to each target lun is no longer
seen on the initiator side.This in turn breaks multipathing on my
initiators because it is seeing unique identifiers even though the
targets are the same.

This is a trivial example of the issue that I see. I have a target disk
(wwm 0x50014ee6036945cb) that I export with tgtd. Below is the
descriptor on the target from the host system:

[root at cio-5 ~]# sg_inq --page=0x83 /dev/sdj
VPD INQUIRY: Device Identification page
Designation descriptor number 1, descriptor length: 12
designator_type: NAA, code_set: Binary
associated with the addressed logical unit
NAA 5, IEEE Company_id: 0x14ee
Vendor Specific Identifier: 0x6036945cb
[0x50014ee6036945cb]

I run two instances of tgtd on two seperate Infiniband interfaces and
export the target on both so that I can use multipathd to provide
redundancy. I configure the lun using the following targets.conf file.

default-driver iser
<target
iqn.2012-07.com.cacheio:cio-5.cio-ATA-WDC_WD5000LPVX-5-350014ee6036945cb>
<backing-store /dev/disk/cacheio/ATA-WDC_WD5000LPVX-5-350014ee6036945cb>
lun 1
vendor_id "ATA "
product_id "WD5000LPVX-5"
product_rev "1A01"
scsi_sn "WX81A33E1930"
scsi_id 350014ee6036945cb
bs-type aio
mode_page "0x0A:1:4:0x01:0x04:0x0:0x0"
write-cache off
</backing-store>
</target>

Then I connect the initiator to the lun over the two paths. They appear
as sdb and sdc. Now when I look at the descriptors from the initiator, I
see two descriptors for each lun:

[root at cio-2 ~]# sg_inq --page=0x83 /dev/sdb
VPD INQUIRY: Device Identification page
Designation descriptor number 1, descriptor length: 40
designator_type: T10 vendor identification, code_set: ASCII
associated with the addressed logical unit
vendor id: 350014ee
vendor specific: 6036945cb
Designation descriptor number 2, descriptor length: 12
designator_type: NAA, code_set: Binary
associated with the addressed logical unit
NAA 3, Locally assigned:
[0x3000000200000001]

[root at cio-2 ~]# sg_inq --page=0x83 /dev/sdc
VPD INQUIRY: Device Identification page
Designation descriptor number 1, descriptor length: 40
designator_type: T10 vendor identification, code_set: ASCII
associated with the addressed logical unit
vendor id: 350014ee
vendor specific: 6036945cb
Designation descriptor number 2, descriptor length: 12
designator_type: NAA, code_set: Binary
associated with the addressed logical unit
NAA 3, Locally assigned:
[0x3000000100000001]

Notice that the NAA descriptors are now different even though the target
is the same!

[root at cio-2 tgt]# scsi_id --whitelisted --page=0x83 /dev/sdb
33000000200000001
[root at cio-2 tgt]# scsi_id --whitelisted --page=0x83 /dev/sdc
33000000100000001

This has the effect of breaking multipathd because the identifiers no
longer match...

[root at cio-2 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 93.2G 0 disk
├─sda1 8:1 0 1000M 0 part /boot
└─sda2 8:2 0 87.9G 0 part
├─vg_cio-lv_root (dm-0) 253:0 0 78.1G 0 lvm /
└─vg_cio-lv_home (dm-1) 253:1 0 9.8G 0 lvm /home
sdb 8:16 0 465.8G 0 disk
└─33000000200000001 (dm-2) 253:2 0 465.8G 0 mpath
sdc 8:32 0 465.8G 0 disk
└─33000000100000001 (dm-3) 253:3 0 465.8G 0 mpath

[root at cio-2 tgt]# multipath -ll
33000000100000001 dm-3 ATA,WD5000LPVX-5
size=466G features='0' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=-1 status=active
`- 32:0:0:1 sdc 8:32 active ready running
Oct 16 19:19:06 | sdb: alua not supported
33000000200000001 dm-2 ATA,WD5000LPVX-5
size=466G features='0' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=-1 status=active
`- 31:0:0:1 sdb 8:16 active ready running

I've reverted the commit for my local systems to restore the previous
behavior. But I'm interested in correctly assigning the NAA instead of
using the generated one.

Eric




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