On Tue, 2015-01-06 at 14:39 -0800, Nicholas A. Bellinger wrote: > On Tue, 2014-12-23 at 09:28 +0100, Christoph Hellwig wrote: > > On Mon, Dec 22, 2014 at 11:31:53AM +0100, Stefan Priebe - Profihost AG wrote: > > > Hi, > > > > > > since the below patch i've some problems with iscsi. > > > > > > The LIO based iscsi Server is full of messages like this: > > > SCSI OP 2ah with too big sectors 8344 exceeds fabric_max_sectors: 8192 > > > > > > And the client says: > > > Buffer I/O error on device sdd, logical block 38861907 > > > lost page write due to I/O error on sdd > > > > > > May be some code fixes for iscsi client is missing? > > > > No, the problem seems that the the target is enforcing a size limit > > without communicating it through the block limits EVPD page. > > > > Nic, can you fix LIO to expose the proper max xfer size? > > The fabric_max_sectors=8192 value is already being exposed by target in > block limits EVPD as MAXIMUM TRANSFER LENGTH. > > I'm guessing that since the host side support was not added until June > 2014 in commit bcdb247c by MKP, Stefan is likely using an earlier > initiator that is not honoring this value. > > However, this same issue has been reported elsewhere [1] with an MSFT FC > host sending I/Os of 8 MB that also doesn't appear to honor block limits > MAXIMUM TRANSFER LENGTH either. > > So that said, I think it's about time to go ahead and drop the arbitrary > limitation of fabric_max_sectors, and simply enforce a sane limit (eg: > not UINT_MAX) for hw_max_sectors. > > The only limitations for backends that I'm aware of is the FILEIO > FD_MAX_BYTES limit for the number of iovecs per vfs_[writev,readv] call, > and for IBLOCK what queue_max_hw_sectors() reports for raw block > make_request() based drivers that aren't able to > ... split large I/O requests into smaller ones. > I'll put together a patch soon to drop the fabric_max_sectors stuff, and > use the existing hw_max_sectors to enforce any backend specific I/O size > limitations. > > --nab > > [1] http://www.spinics.net/lists/target-devel/msg08024.html > > -- > To unsubscribe from this list: send the line "unsubscribe target-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
