[dm-devel] RE: regarding path failback using HSV110 array.

[christophe varoqui]

/var/log/message log would be good to see.

Regards,
cvaroqui

On ven, 2005-06-17 at 15:11 +0530, Murthy, Narasimha Doraswamy (STSD)
wrote:
> In the previous logs, the multipath daemon wasn’t running. Attached is
> the new log file, which has the path checker logs too.
> 
> -Murthy
> 
>  
> 
>                                    
> ______________________________________________________________________
> From: Murthy, Narasimha Doraswamy (STSD) 
> Sent: Friday, June 17, 2005 1:02 PM
> To: 'dm-devel at redhat.com'
> Subject: regarding path failback using HSV110 array.
> 
> 
>  
> 
> Hi Alasdair,
> 
> As per yesterday’s teleconf, I am sending the snapshot of
> the /var/log/messages, which has the messages logged when testing the
> basic failback functionality.  The testing is conducted on the host
> with RHEL U1 and single controller of HP Storageworks HSV110 array. As
> each HSV110 controller has 2 ports, we effectively see 2 paths per
> lun. I am using 0.4.5.44 version of multipath tools.  
> 
>  
> 
> Following is the observation during testing the path failback.
> 
>  
> 
> a) When the path is made unavailable (/dev/sdd) for a logical device
> “mp1” on a  multipath target, the status of the path becomes
> [faulty][active]
> 
>  
> 
> mp1
> 
> [size=1 GB][features="0"][hwhandler="0"]
> 
> \_ round-robin 0 [active][best]
> 
>   \_ 0:0:0:1 sda  8:0     [faulty][active]
> 
> \_ round-robin 0 [enabled]
> 
>   \_ 1:0:0:1 sdd  8:48    [ready][active]
> 
>  
> 
> b) When an dd is executed on /dev/mapper/mp1 (dd if=/dev/zero
> of=/dev/devmapper/mp1), the state of the paths is as follows
> 
> mp1
> 
> [size=1 GB][features="0"][hwhandler="0"]
> 
> \_ round-robin 0 [enabled]
> 
>   \_ 0:0:0:1 sda  8:0     [faulty][failed]
> 
> \_ round-robin 0 [active][best]
> 
>   \_ 1:0:0:1 sdd  8:48    [ready ][active]
> 
>  
> 
>  
> 
> c) Now if the path (/dev/sda) is made available for the same logical
> device, the status is as follows
> 
> mp1
> 
> [size=1 GB][features="0"][hwhandler="0"]
> 
> \_ round-robin 0 [enabled]
> 
>   \_ 0:0:0:1 sda  8:0     [ready ][failed]
> 
> \_ round-robin 0 [active][best]
> 
>   \_ 1:0:0:1 sdd  8:48    [ready ][active]
> 
>  
> 
> Note the path “/dev/sda” has become [ready][failed] not
> [ready][active]. For this to change to [ready][active], “multipath –
> v0” needs to be executed manually.
> 
>  
> 
> d) Now if path “/dev/sdd” is made unavailable, then if “dd” is run
> on /dev/mapper/mp1, it returns with input/output error, as none of the
> path will be in [ready][active] state. The following is the state now:
> 
>  
> 
> mp1
> 
> [size=1 GB][features="0"][hwhandler="0"]
> 
> \_ round-robin 0 [enabled][best]
> 
>   \_ 0:0:0:1 sda  8:0     [ready ][failed]
> 
> \_ round-robin 0 [enabled]
> 
>   \_ 1:0:0:1 sdd  8:48    [faulty][failed]
> 
>  
> 
>  
> 
> If “multipath –v0” executed from the command prompt the states get
> updated properly as
> 
>  
> 
> mp1
> 
> [size=1 GB][features="0"][hwhandler="0"]
> 
> \_ round-robin 0 [active][best]
> 
>   \_ 0:0:0:1 sda  8:0     [ready ][active]
> 
> \_ round-robin 0 [enabled]
> 
>   \_ 1:0:0:1 sdd  8:48    [faulty][active]
> 
>  
> 
> After this I will be able to do IO using “dd”.   How do we make the
> path state update properly with out manually invoking “multipath –
> v0”? 
> 
> I am not sure on how to get the debug build of multipath and
> multipathd binaries, if the information in the messages.txt is
> insufficient, I need to test with the debug build and send the new
> log.
> 
>  
> 
> Any help in resolving this problem is appreciated.
> 
>  
> 
> Thanks and regards
> 
> Murthy
> 
>  
> 
> 
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-- 
christophe varoqui <christophe.varoqui at free.fr>