topic Re: Determining current path with qlogic failover driver in Operating System - Linux

Determining current path with qlogic failover driver

Simon Hargrave — Mon, 01 Aug 2005 10:07:47 GMT

I have a setup with an MSA1000 (with 2 2/8 switches internal) and external DL380 servers dual-pathed to the MSA.

I am using the qlogic driver in failover mode to maintain redundancy, and everyting seems to work as expected.

What I would like to know though is is there a way to determine at any point in time which path is "active"?

For example on our server with 3 LUNS, if I disable failover I see each LUN twice as I would expect: -

[root@ybsllx70 root]# lssd
sda 0,0,0,1 COMPAQ MSA1000 VOLUME 4.32 5008-05f3-000f-21f1
sdb 0,0,0,2 COMPAQ MSA1000 VOLUME 4.32 5008-05f3-000f-21f1
sdc 0,0,0,3 COMPAQ MSA1000 VOLUME 4.32 5008-05f3-000f-21f1
sdd 2,0,0,1 COMPAQ MSA1000 VOLUME 4.32 5008-05f3-000f-21f9
sde 2,0,0,2 COMPAQ MSA1000 VOLUME 4.32 5008-05f3-000f-21f9
sdf 2,0,0,3 COMPAQ MSA1000 VOLUME 4.32 5008-05f3-000f-21f9

then with failover enabled I only see each LUN once, again as expected:

[root@ybsllx70 root]# lssd
sda 0,0,0,1 COMPAQ MSA1000 VOLUME 4.32 5008-05f3-000f-21f1
sdb 0,0,0,2 COMPAQ MSA1000 VOLUME 4.32 5008-05f3-000f-21f1
sdc 0,0,0,3 COMPAQ MSA1000 VOLUME 4.32 5008-05f3-000f-21f1

So in this case it would appear that the devices through HBA 0 are in use. However if I pull fibre to force a failover this display never changes, it's as if it's however the LUNs were first detected at boot time.

So 2 questions: -

1) Is there a way to determine which path the failover driver is ACTUALLY using for a given LUN?

2) Is there a way to force a failover from software? For example if using SecurePath you can do this with spmgr, is there a method with the failover driver, short of pulling out wires?

Re: Determining current path with qlogic failover driver

Uwe Zessin — Mon, 01 Aug 2005 10:15:29 GMT

All my installations have been with Secure Path so far and I didn't have time to play with the driver's embedded failover capabilities :-(

HP now provides the SANsurfer manager:
http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?locale=en_US〈=English+%28US%29&pnameOID=315741&prodSeriesId=315739&prodTypeId=12169&basePartNum=COL10519&locBasepartNum=co-30629-2&os=SUSE+LINUX+Enterprise+Server+8&tech=Utility++FC+HBA
(there is a different kit for X86_64 available, too)

it might be possible that it has controls similar to SPMGR.

Re: Determining current path with qlogic failover driver

generic_1 — Mon, 01 Aug 2005 18:50:52 GMT

It was looking at some of the pictures on qlogics site and I think you need the sansurfer component to see what you want.

Re: Determining current path with qlogic failover driver

Simon Hargrave — Tue, 02 Aug 2005 09:12:48 GMT

Was hoping that there'd be a way without installing SANsurfer, after all it's a fairly hefty Java install just to see which path is in use!

In fact I have installed it and can't really see the information I want anyway.

But I do have to say that the failover driver seems much more stable than my tests with secure path. For example one of my test (using the MSA1000 which is active-passive) involved removing fibre such that server A required controller A and server B requiring controller B. secure path swapped from one to the other a few times then eventually hung, and the LUNs hung preventing a clean reboot of the server. failover handles this happily and merrily swaps between the controllers servicing each hosts requests as required, haven't managed to hang it once yet!