Re: [dm-devel] [multipath] SCSI device capacity mess

[christophe varoqui <christophe.varoqui@free.fr>]

> > I'm just saying we should stop on the first failed command (TUR) and not
> > retry to read all 64 sectors regardless. I can live with one error per
> > passive path, but 64 really kills the logs.
> 
> That makes sense.
> 
> What is the result of the TUR? I did not see any information about it in other posts in this thread.
> 

the tur checker in multipath-tools report ghosts as failing.

> We should change state somehow if the TUR failed or was not ready, maybe
> call set_media_not_present(), or maybe change the sdev state to
> SDEV_OFFLINE - though that might cause extra logging.
> 
> We might not normally every hit this since the scan (INQUIRY failure)
> would likely prevent the device from showing up at all. 

scsi_id and INQUIRY succeed on ghost paths, which allow multipath to
group them with valid paths to the same LU.

> Plus, we only call sd_spinup_disk() during discovery and not on open,
> unlike the calls to sd_media_changed().
> 
Would it be workable to add a scsi_devinfo flag for devices with ghosts.
If this flag is set and state is down, open calls sd_media_changed().
The multipath-tools and device-mapper will try as hard as possible to
avoid opening those device if not necessary, by grouping them in a low
priority path group.

regards,
-- 
christophe varoqui <christophe.varoqui@free.fr>