[dm-devel] info on enabling only one path with rdac and DS4700

[Moger, Babu]

> -----Original Message-----
> From: Gianluca Cecchi [mailto:gianluca.cecchi at gmail.com]
> Sent: Tuesday, November 15, 2011 9:34 AM
> To: device-mapper development
> Subject: [dm-devel] info on enabling only one path with rdac and DS4700
> 
> Hello,
> with RH EL 5.7 x86_64 and updates:
> # uname -r
> 2.6.18-274.7.1.el5
> # rpm -q device-mapper-multipath
> device-mapper-multipath-0.4.7-46.el5_7.1
> 
> I'm on a IBM HS21 blade connected to a DS4700 storage array.
> Without doing nothing in multipath.conf but blacklisting the internal
> disk, I get this kind of configuration:
> # multipath -l
> mpath1 (3600a0b80005012440000093e4a55cf33) dm-6 IBM,1814      FAStT
> [size=3.4T][features=1 queue_if_no_path][hwhandler=1 rdac][rw]
> \_ round-robin 0 [prio=0][active]
>  \_ 3:0:0:1 sdb 8:16  [active][undef]
>  \_ 4:0:0:1 sdc 8:32  [active][undef]
> \_ round-robin 0 [prio=0][enabled]
>  \_ 3:0:1:1 sdd 8:48  [active][undef]
>  \_ 4:0:1:1 sde 8:64  [active][undef]

This output looks good to me. I don’t see any problem..

> 
> Is there any config option I can force to use only one path at a time
> in the active controller, instead of two (sdb and sdc in my case) in
> round robin as I see in iostat?

Not sure about the purpose of this. Either you have to blacklist by device node(sdb or sdc) or change your config to see only one path to the controller.

> 
> Also, I noticed that output with "-ll" shows "200" as priority of
> paths for the active controller, while "-l" shows 0 for both (see
> above)...
> Is this a bug or expected difference due to command different
> switch/verbosity?

It is not a bug. It will not run all the commands if you run with "-l"

> (I see similar behaviour also with another server connected to a
> DS6800 storage array)
> # multipath -ll
> mpath1 (3600a0b80005012440000093e4a55cf33) dm-6 IBM,1814      FAStT
> [size=3.4T][features=1 queue_if_no_path][hwhandler=1 rdac][rw]
> \_ round-robin 0 [prio=200][active]
>  \_ 3:0:0:1 sdb 8:16  [active][ready]
>  \_ 4:0:0:1 sdc 8:32  [active][ready]
> \_ round-robin 0 [prio=0][enabled]
>  \_ 3:0:1:1 sdd 8:48  [active][ghost]
>  \_ 4:0:1:1 sde 8:64  [active][ghost]
> 
> I would like to use default multipath instead of LSI provided rdac,
> found at
> http://www.lsi.com/sep/Pages/rdac/ds4000.aspx
> version 09.03.0C05.0504 ,  dated	7/18/2011 with:
> New linux kernel versions supported with this release:
>              - SLES 10-SP3: 2.6.16.60-0.54.5
>              - SLES 10-SP4: 2.6.16.60-0.85.1
>              - SLES 11.1  : 2.6.32.12-0.7
>              - RHEL5-u5   : 2.6.18-194
>              - RHEL5-u6   : 2.6.18-238
>              - RHEL6      : 2.6.32-71
> 
> In fact I'm using  2.6.18-274.7.1.el5 that is not listed...
> Any known cons in using device-mapper-multipath with IBM,1814?
> 
> Thanks in advance,
> Gianluca
> 
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