VA7410 Alternate Paths

[Bob Ferro]

I have a VA7410 (2 controllers) with 60 LUNs. Each LUN shows as a primary (c10t0d1, etc.) and a secondary (c12t0d1, etc.) paths. I did a pvcreate on both primary and secondary. I create a VG with vgcreate (vgcreate vg05 /dev/dsk/c10t8d2 /dev/dsk/c12t8d2). vgdisplay shows
PV Name /dev/dsk/c10t8d2
PV Name /dev/dsk/c12t8d2 Alternate Link.

But when I look thru SAM, I see the c12t8d2 as "UNUSED" and 1 path. The c10t8d2 shows as "LVM", vg05 and 1 path. Why aren't there 2 paths? Was it the pvcreate on the alt path?

[Patrick Wallek]

My guess is that SAM is just confused. Running a pvcreate on both path's will not do any harm, thought it is NOT necessary.

You might check and see if you have the latest SAM patches installed for whatever version of HP-UX you are running.

[TTr · Accepted solution]

You did not do anything wrong. I agree with Patric that SAM is confused. Read my personal profile...

One thing to be carefull with the VAs is the device you will as the primary in vgcreate has to be the one that corresponds to the controller with the same redundancy group.

[Torsten.]

SAM is not that bad, but don't trust an old SAM. I would not be surprised if this is an 11.00 or early 11.11 system without patches ...


I agree, you should check if the primary path goes to the controller that owns the LUN.

[Bob Ferro]

One question about "the device you will use as the primary in vgcreate has to be the one that corresponds to the controller with the same redundancy group". If I create and assign 4 LUNs to vg01 and they have a device of c10t0d1-c10t0d4 primary and c12t0d1-c12t0d4 secondary, were c10t0d1(c12t0d1) and c10t0d3(c12t0d3) = rg1 and c10t0d2(c12t0d2) and c10t0d4(c12t0d4) = rg2, which vgcreate would I use, opt1 or opt2? How does the sequence of disk devices matter when using more that one?

vgcreate vg01 /dev/dsk/c10t0d1 /dev/dsk/c12t0d1 /dev/dsk/c10t0d2 /dev/dsk/c12t0d2 /dev/dsk/c10t0d3 /dev/dsk/c12t0d3 /dev/dsk/c10t0d4 /dev/dsk/c12t0d4

or

vgcreate vg01 /dev/dsk/c10t0d1 /dev/dsk/c12t0d1 /dev/dsk/c12t0d2 /dev/dsk/c10t0d2 /dev/dsk/c10t0d3 /dev/dsk/c12t0d3 /dev/dsk/c12t0d4 /dev/dsk/c10t0d4

[Torsten.]

I can't tell you because of not enough information about your config.

You'll get a similar information from

# armdsp -a
...
LUN 1:
Redundancy Group:_____________________1
Active:_______________________________True
Data Capacity:________________________20 GB
...

This means LUN 1 is in RG 1 and C1 is the owner. The owner of RG 2 is C2.

If a LUN is in RG 1 you should use the HBA as primary, which is connected to C1, the HBA connected to C2 will be the secondary.
This will ensure performance.

[Bob Ferro]

Here's the breakdown:

LUN 1 = rg1 = C1 = c10t0d1 (c12t0d1 alt.)
LUN 2 = rg2 = C2 = c10t0d2 (c12t0d2 alt.)
LUN 3 = rg1 = C1 = c10t0d3 (c12t0d3 alt.)
LUN 4 = rg2 = C2 = c10t0d4 (c12t0d4 alt.)

If odd disk are rg1 and even disk are rg2, when I created LUN 1 and 3, I assigned them to rg1 and when I created LUN 2 and 4, I assigned them to rg2.

armcfg â L 1 â a 20G â g 1 50060b000014e985
armcfg â L 2 â a 20G â g 2 50060b000014e985
armcfg â L 3 â a 20G â g 1 50060b000014e985
armcfg â L 4 â a 20G â g 2 50060b000014e985

[Bob Ferro]

That's armcfg -L

[Bob Ferro]

Correction:

armcfg -L 1 -a 20 G -g 1, etc. Copy and paste sometimes doesn't work too good.

[Torsten.]

>>
LUN 1 = rg1 = C1 = c10t0d1 (c12t0d1 alt.)
LUN 2 = rg2 = C2 = c10t0d2 (c12t0d2 alt.)
LUN 3 = rg1 = C1 = c10t0d3 (c12t0d3 alt.)
LUN 4 = rg2 = C2 = c10t0d4 (c12t0d4 alt.)


This cannot be true!

c10 is related to 1 HBA, c12 to another.

A single HBA cannot be connected to both VA controllers (usually).

I would assume something like

LUN 1 = rg1 = C1 = c10t0d1 (c12t0d1 alt.)
LUN 2 = rg2 = C2 = c12t0d2 (c10t0d2 alt.)
...

[Bob Ferro]

Then how can I relate every LUN to a hardware path/device file? If I have 60 LUNs (30 rg1 and 30 rg2), and I do an ioscan -fnCdisk and I see 60 /dev/dsk/c10txdx and 60 /dev/dsk/c12txdx, which one is which? According to man vgcreate, the 1st pv-path is primary and the 2nd pv-path is secondary. If I have more than one LUN assigned, is it vgcreate vg01 pp sp pp sp, etc or vgcreate vg01 pp sp sp pp, etc?

[Bob Ferro]

One thing to add, I have 2 Dual-Port 4 Gig FC HBA, one FC from HBA 1 to controller 1 and one FC from HBA 2 to controller 2. Dah, I had a senior moment.

[Torsten.]

Try this, maybe it helps you to get more info:

# armtopology

[Bob Ferro]

Here's the results:

phl1s425 50060b00006a3411 50060b00006a3410 A6218A 00SG229J0018 2 2 0 phl1s425.dscp.dla.mi /dev/dsk/c12t0d0

[Torsten.]

>>
phl1s425 50060b00006a3411 50060b00006a3410 A6218A 00SG229J0018 2 2 0 phl1s425.dscp.dla.mi /dev/dsk/c12t0d0

Do you think I always know what all this means? VA is an old array - long time ago...

But after some research ...

C_RG_LUN___Device Path
2_2___0____/dev/dsk/c12t0d0


If this is correct, your RG 2 is related to c12...

[TTr]

armdsp -a and ioscan -fnk can straighten this thing out.

If you look in armdsp output under the "CONTROLLERS" section you will see controller M/C1 and M/C2. Under each controller look for the hardware path line

Lets say M/C1 is
Hardware Path:_________0/12/0/0.8.0.108.0.0.0

and M/C2 is
Hardware Path:_________0/10/0/0.8.0.110.0.0.0

Further down in the LUN sections you will see the Redundancy group for each LUN. It is either 1 or 2 for M/C1 and M/C2. You will need this for each LUN. It is usually odd/even as you mentioned.

Then you look in the ioscan listing and identify both hardware paths for each LUN. One LUN path will start with 0/12/0/0... and the other 0/10/0/0... Each of these paths will have a hardware device associated with it. Let say c12 is for the 0/12 and c10 for the 0/0.

For the LUNs that belong to RG1 use c12tXdY as the primary and c10tXdY as the alternate path in vgcreate. For the LUNs that belong to RG2 use c10tXDY as the primary and C12tXdY as the alternate.

[Bob Ferro]

Hey guys, thanks for all the info. I had one path down, I had to do an armdiscover and now everything shows as 2 paths.