When using Dell MD3xxxi SAN, I see a 20MB LUN for Universal Xport

Question

When using Dell MD3xxxi SAN, I see a 20MB LUN for Universal Xport.

Answer

After connecting to the iSCSI target and configuring multipath, you may see the following: 

[root@localhost ~]# multipath -ll
mpath2 (36782bcb00074994a000003554fab646b) dm-3 DELL,MD32xxi
[size=2.2T][features=3 queue_if_no_path pg_init_retries 50][hwhandler=1 rdac][rw]
\_ round-robin 0 [prio=400][active]
 \_ 28:0:0:1  sdn 8:208  [active][ready]
 \_ 25:0:0:1  sdo 8:224  [active][ready]
 \_ 22:0:0:1  sdp 8:240  [active][ready]
 \_ 27:0:0:1  sdq 65:0   [active][ready]
\_ round-robin 0 [prio=0][enabled]
 \_ 21:0:0:1  sdj 8:144  [active][ghost]
 \_ 24:0:0:1  sdk 8:160  [active][ghost]
 \_ 23:0:0:1  sdl 8:176  [active][ghost]
 \_ 26:0:0:1  sdm 8:192  [active][ghost]
mpath1 (36782bcb00074994a000003514fab6464) dm-2 DELL,MD32xxi
[size=2.2T][features=3 queue_if_no_path pg_init_retries 50][hwhandler=1 rdac][rw]
\_ round-robin 0 [prio=400][active]
 \_ 21:0:0:0  sdb 8:16   [active][ready]
 \_ 24:0:0:0  sde 8:64   [active][ready]
 \_ 23:0:0:0  sdf 8:80   [active][ready]
 \_ 26:0:0:0  sdi 8:128  [active][ready]
\_ round-robin 0 [prio=0][enabled]
 \_ 25:0:0:0  sdc 8:32   [active][ghost]
 \_ 28:0:0:0  sdd 8:48   [active][ghost]
 \_ 27:0:0:0  sdg 8:96   [active][ghost]
 \_ 22:0:0:0  sdh 8:112  [active][ghost]
mpath3 (36d4ae5200093d2b7000003054fa30b82) dm-4 DELL,Universal Xport
[size=20M][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=8][active]
 \_ 25:0:0:31 sdr 65:16  [active][ready]
 \_ 28:0:0:31 sds 65:32  [active][ready]
 \_ 27:0:0:31 sdt 65:48  [active][ready]
 \_ 22:0:0:31 sdu 65:64  [active][ready]
 \_ 21:0:0:31 sdv 65:80  [active][ready]
 \_ 24:0:0:31 sdw 65:96  [active][ready]
 \_ 23:0:0:31 sdx 65:112 [active][ready]
 \_ 26:0:0:31 sdy 65:128 [active][ready]

These 'Universal Xport' volume can be excluded from multipath by adding the following to /etc/multipath.conf:

blacklist {
device {
             vendor  "*"
             product "Universal Xport"
     }
}