[dm-devel] multipath with SAS and FC.

[bchatelain at cines.fr]

Hello,

I try to use multipath with SAS disk, transported by Fiber Channel, on
Dell Compellent.
My volume is detected on 2x R440 PowerEdge hosted by Centos 8 and
orchestrated by oVirt.


Problematic :

On my two ovirt node with the same configuration and hardware
specifications,
I give this same behavor, one of my two link, is flapping ACTIVE to FAILED

Something like this :
# multipath -ll
36000d31003d5c2000000000000000010 dm-3 COMPELNT,Compellent Vol
size=1.5T features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
`-+- policy='service-time 0' prio=25 status=active
   |- 1:0:0:2 sdb 8:16 active ready running
   `- 1:0:1:2 sdc 8:32 failed ready running   -- looping failed/ready


Some interesting stuff :

# multipathd show config : Full @ https://pastebin.fr/85965

blacklist {
···
     device {
         vendor "COMPELNT"
         product "Compellent Vol"
         path_grouping_policy "multibus"
         no_path_retry "queue"
     }
···
}

 LogZ : Full @ https://pastebin.fr/85968
Feb 25 11:48:24 isildur-adm kernel: device-mapper: multipath: 253:3: Reinstating path 8:32.
Feb 25 11:48:24 isildur-adm kernel: sd 1:0:1:2: alua: port group f01c state S non-preferred supports toluSNA
Feb 25 11:48:24 isildur-adm kernel: device-mapper: multipath: 253:3: Failing path 8:32.
Feb 25 11:48:25 isildur-adm multipathd[659460]: sdc: mark as failed


 # lsscsi -l
[0:2:0:0]    disk    DELL     PERC H330 Adp    4.30  /dev/sda
   state=running queue_depth=256 scsi_level=6 type=0 device_blocked=0 timeout=90
[1:0:0:2]    disk    COMPELNT Compellent Vol   0704  /dev/sdb
   state=running queue_depth=254 scsi_level=6 type=0 device_blocked=0 timeout=30
[1:0:1:2]    disk    COMPELNT Compellent Vol   0704  /dev/sdc
   state=running queue_depth=254 scsi_level=6 type=0 device_blocked=0 timeout=30


 # lsmod | grep fc
bnx2fc                110592  0
cnic                   69632  1 bnx2fc
libfcoe                77824  2 qedf,bnx2fc
libfc                 147456  3 qedf,bnx2fc,libfcoe
scsi_transport_fc      69632  3 qedf,libfc,bnx2fc


 # lsmod | grep sas
mpt3sas  303104 4
raid_class  16384 1 mpt3sas
megaraid_sas  172032 2
scsi_transport_sas  45056 1mpt3sas



I've made a misconfiguration ?
Is It possible to use SAS over FC ?

Thank you.


Regards,
Benoit Chatelain.