>>>>> "Mike" == Mike Snitzer <snitzer@xxxxxxxxxx> writes:
Mike> So that makes 3 different _prominent_ storage vendors, that I am
Mike> aware of, that are bitten by their broken storage (relative to
Mike> discard and properly advertising which variant they actually
Mike> support). I'd much rather deal with the storage vendors (or their
Mike> customers) reporting that discards aren't working than mutual
Mike> customers reporting that they cannot even install to the storage.
More graceful handling of the sense data aside, we do have a couple of
options:
1. Now that the provisioning portion seems to be stable in SBC-3 we can
nuke the interim spec heuristics and only support devices that
report the right thing. This may disable provisioning for some
existing users whose arrays run non-compliant firmware.
2. We can add another layer of heuristics based on the RSOC wrapper I
introduced for write same. Maybe you could send me sg_opcodes output
for the arrays in question?
Mike> The ultimate fix is clear: storage vendors need to fix their
Mike> storage (2 of the 3 have, 1 is working on it). But a Linux-only
Mike> workaround for this series of unfortunate events (particularly as
Mike> it happens with multipath in the mix) is to have SCSI classify
Mike> certain ILLEGAL_REQUEST as the TARGET_ERROR that they are.
I don't have a fundamental problem with your patch. But since we
explicitly handle ILLEGAL REQUEST with 0x20 and 0x24 in sd.c I wonder
what's broken? We should disable discard support if the WRITE SAME w/
UNMAP fails.
I'll see if I can figure out what's going on unless you beat me to it...
--
Martin K. Petersen Oracle Linux Engineering
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