Mike Christie wrote:
goggin, edward wrote:
Mike,
I don't think it is reasonably possible to anticipate
all possible parsing requirements for the asc and ascq
portions of SCSI sense information across all device
models. I'm in favor of having a "small" framework in
SCSI where a SCSI sense interpreter module (per
vendor & model possibly) could be registered
dynamically, by dm-emc.c for instance.
Yeah I agree, I mentioned this before in some other mails. I think a
module versus some table that userspace could write to were discussed.
The BLKERR values were meant to be able to tell upper layer code whether
a transport or device or driver error occured and whether the lower
level thought it was retryable. But then I thought I could also wedge in
the handling of the vendor specifcs by adding a vendor specific SCSI
module that would map the their specific value to a BLKERR_* one. And as
I said offlist it is not working perfectly becuase we are losing some
information in the translations.
Oh yeah so the problem I am having is emc boxes may return "LUN Not
Ready - Manual Intervention Required". When dm-emc.c sees this error it
wants to bypass a group of paths and retry the IO but under ceratin
conditions not fail those paths. So I am not sure what to return for
this error. I thought if I redo my BLKERR so they describe the error like
BLKERR_DEV_NOT_READY
BLKERR_MANUAL_INTERVENTION_REQ
BLKERR_NOT_CONN
... and set them up as a bitmap like suggested by JamesB. I could return
BLKERR_MANUAL_INTERVENTION_REQ from a scsi module then have dm-emc.c
evaluate that value to a dm-mpaths return value of "MP_BYPASS_PG |
MP_RETRY_IO" which means bypass the priority group (group of paths) and
retry the IO.
But as more vendors use dm and they cannot use existing BLKERR values I
have to add more and more. And then we have to handle the case where
some block layer code may return BLKERR_MANUAL_INTERVENTION_REQ for
something not related to the reasons EMC's HW was returning "LUN Not
Ready - Manual Intervention Required" and we end up with getting things
wrong.
