sas_mpath_snic_alias AttributeError: 'NoneType' object has no attribute 'enclosure'

[snehring]

sas_mpath_snic_alias seems to depend on all subdevices of a multipath dm entry having an enclosure_device symlink in /sys/block/dm-37/slaves/*/device. There are some cases where this doesn't happen due to a bug in the ses driver (seemingly when you have multipath split between multiple hbas and jbod controllers). I have a ticket open with our OS vendor to hopefully address this, but I've been looking into ways to work around it in the mean time.

If you run sas_mpath_snic_alias on in impacted host you get the following

[root@host ~]# sas_mpath_snic_alias dm-6
Traceback (most recent call last):
  File "/usr/bin/sas_mpath_snic_alias", line 11, in <module>
    load_entry_point('sasutils==0.6.1', 'console_scripts', 'sas_mpath_snic_alias')()
  File "/usr/lib/python3.6/site-packages/sasutils/cli/sas_mpath_snic_alias.py", line 97, in main
    result = sas_mpath_snic_alias(sys.argv[1])
  File "/usr/lib/python3.6/site-packages/sasutils/cli/sas_mpath_snic_alias.py", line 63, in sas_mpath_snic_alias
    ses_sg = blkdev.scsi_device.array_device.enclosure.scsi_generic.sg_name
AttributeError: 'NoneType' object has no attribute 'enclosure'

from

sasutils/sasutils/cli/sas_mpath_snic_alias.py

Line 63 in fd8e57d

ses_sg = blkdev.scsi_device.array_device.enclosure.scsi_generic.sg_name

I think it's safe to alter the code in sas_mpath_snic.alias.py to be

try:
    ses_sg = blkdev.scsi_device.array_device.enclosure.scsi_generic.sg_name
except AttributeError:
    # due to ses driver issue not every devicemapper node may have an enclosure populated
    continue

but I'm not super familiar with the code base to be completely certain of that.