Bug#623611: Lot of IO errors during boot

[Ritesh Raj Sarraf]

On 04/22/2011 03:30 PM, Laurent Bigonville wrote:
> > > size=500G features='1 queue_if_no_path' hwhandler='1 rdac' wp=rw
>>> > > |-+- policy='round-robin 0' prio=12 status=active
>>> > > | |- 0:0:1:1 sdb 8:16 active ready running
>>> > > | `- 1:0:1:1 sdd 8:48 active ready running
>>> > > `-+- policy='round-robin 0' prio=2 status=enabled
>>> > >   |- 0:0:0:1 sda 8:0  active ghost running
>>> > >   `- 1:0:0:1 sdc 8:32 active ghost running
Okay!! I never got to this one because I never worked with this target.
Thank you. It is always good to know more. :-)
The secondary paths (or in this case, the ghost paths) are, by design,
supposed to fail on I/O requests. But they should respond to
read_capacity and other commands. More details as described in the
source code itself:

     * PATH_GHOST:
     * - Use: Only hp_sw and rdac
     * - Description: Indicates a "passive/standby" path on
    active/passive HP
     *   arrays.  These paths will return valid answers to certain SCSI
    commands
     *   (tur, read_capacity, inquiry, start_stop), but will fail I/O
    commands.
     *   The path needs an initialization command to be sent to it in
    order for
     *   I/Os to succeed.
     *

So going back to this bug reports actual question. If the multipathed
map is working, there's no bug. You could ignore these scsi errors. This
is similar to a faults scenario. At faults, during the recovery timeo,
scsi throws a lot of error messages, which should be ignored.

-- 
Ritesh Raj Sarraf
RESEARCHUT - http://www.researchut.com
"Necessity is the mother of invention."

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