dual controllor MSA2012fc, I only see 2 paths and not 4

[John Paget Bourke]

Hi,

I have a two Blade servers with one internal dual port Qlogic card each.

These are connected to two SAN (A and B) switches in the interconnect bays.

The SAN switches connect to a MSA2012fc which has two controllors. SANA connects to MSA and MSAB, same for SANB.

Inb similar configurations we should see four paths to each volume (MSA2312fc).

But on this config we see two paths. Each volume can be seen via one MSA controllor via two SAN paths. It should be seen via two MSA controllors via two SAN paths giving four paths.

But what is strange is that I see one volume via one MSA controllor and other volumes via the other MSA controllor.

So from a hardware point of view, all is fine, everything can see everything.

But each MSA controllor is not advertising all LUNs. The mappings in the MSA controllors are for all hosts, so all LUNs should be available to all hosts from both MDS controllors.

So I am not doing any filter, zoning, access lists, nothing except the most basic config.

When I shutdown one controllor, I can see all volumes via the other controllor.

So maybe this is all ok, and the multipath just simply does not show four paths to each volume ?????

Maybe this is a function of the MSA controllors, they only ever show paths to one controllor ???

Here are some traces, when I shut down MSAB Controllor

[root@dba ~]# multipath -ll
mpath2 (3600c0ff000d5a613409ca84a01000000) dm-2 HP,MSA2012fc
[size=137G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
\_ 0:0:0:2 sda 8:0 [active][ready]
\_ 1:0:0:2 sdd 8:48 [active][ready]
mpath1 (3600c0ff000d5a9fe069ea84a01000000) dm-4 HP,MSA2012fc
[size=137G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
\_ 0:0:1:1 sdc 8:32 [active][ready]
\_ 1:0:1:1 sdf 8:80 [active][ready]
mpath0 (3600c0ff000d5a9fe6c98a84a01000000) dm-3 HP,MSA2012fc
[size=137G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
\_ 0:0:1:0 sdb 8:16 [active][ready]
\_ 1:0:1:0 sde 8:64 [active][ready]


Here are some traces, when I shut down MSAA Controllor

[root@dba ~]# multipath -ll
mpath2 (3600c0ff000d5a613409ca84a01000000) dm-4 HP,MSA2012fc
[size=137G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
\_ 0:0:1:2 sdc 8:32 [active][ready]
\_ 1:0:1:2 sdf 8:80 [active][ready]
mpath1 (3600c0ff000d5a9fe069ea84a01000000) dm-3 HP,MSA2012fc
[size=137G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
\_ 0:0:0:1 sdb 8:16 [active][ready]
\_ 1:0:0:1 sde 8:64 [active][ready]
mpath0 (3600c0ff000d5a9fe6c98a84a01000000) dm-2 HP,MSA2012fc
[size=137G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
\_ 0:0:0:0 sda 8:0 [active][ready]
\_ 1:0:0:0 sdd 8:48 [active][ready]

Any ideas ?

Thansks

john

[Uwe Zessin]

What you see is 'technically correct'. On the MSA2000 G1, only one controller presents a volume on its two host ports - that gives two paths. The other controller does not present any path for a volume it does not manage.

[John Paget Bourke]

Hi,

So this solves my paranoia, phew !

Next question is, how does the selection of which controllor is the primary manager for which volume occur ?

Does the controllor which creates the volume become the primary controllor for that volume ?

Thanks

john

[Uwe Zessin · Accepted solution]

A volume is embedded in a 'virtual disk' (= RAID container) which is assigned to a controller.

[John Paget Bourke]

VIRTUAL DISK CONFIG-> vdisk configuration -> Change disk owner !

Got it !

Thanks