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



On Tuesday 15 November 2011 16:34:20 Gianluca Cecchi wrote:
> 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]
> 
> 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?
> 
> 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?
> (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?

The rdac driver from LSI won't even compile, IIRC. With the dm-multipath driver you have to disable AVT on the DS4700. Otherwise the rdac module won't work with the storage.

regards,
  Johannes


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