Great, I will do that. Thank you for all your help! On Wed, Apr 24, 2019 at 6:22 PM Mike Snitzer <[email protected]> wrote:
> On Wed, Apr 24 2019 at 5:27pm -0400, > Mike Snitzer <[email protected]> wrote: > > > > > On Wed, Apr 24 2019 at 10:46am -0400, > > Ryan Norwood <[email protected]> wrote: > > > > > On Wed, Apr 24, 2019 at 9:08 AM Ryan Norwood <[1] > [email protected]> > > > wrote: > > > > > > Thank you for your help. > > > You are correct, it appears that the problem occurs when there is > a RAID > > > 5 or RAID 50 volume beneath VDO. > > > NAME KNAME RA SIZE ALIGNMENT MIN-IO OPT-IO PHY-SEC > LOG-SEC > > > RQ-SIZE SCHED WSAME > > > sdh > > > sdh 128 977.5G 0 512 0 512 512 > 128 > > > deadline 0B > > > +-sed6 > > > dm-6 128 977.5G 0 512 0 512 512 > 128 > > > 0B > > > +-md127 > > > md127 12288 5.7T 0 1048576 6291456 512 512 > 128 > > > 0B > > > +-vdo_data > > > dm-17 128 5.7T 0 1048576 6291456 512 512 > 128 > > > 0B > > > +-vdo > > > dm-18 128 57.3T 0 4096 4096 4096 4096 > 128 > > > 0B > > <snip> > > > > /sys/block/dm-18/queue/max_hw_sectors_kb:4 > > > /sys/block/dm-18/queue/max_sectors_kb:4 > > These are getting set as a side-effect of MD raid imposing the need for > merge_bvec (in the context of RHEL7.x only, not upstream) otherwise it > goes conservative and forces the IO to be contrained to a single page, > please see: > > drivers/md/dm-table.c:dm_set_device_limits() at the end: > > /* > * Check if merge fn is supported. > * If not we'll force DM to use PAGE_SIZE or > * smaller I/O, just to be safe. > */ > if (dm_queue_merge_is_compulsory(q) && !ti->type->merge) > blk_limits_max_hw_sectors(limits, > (unsigned int) (PAGE_SIZE >> 9)); > > With MD raid in the IO stack, dm_queue_merge_is_compulsory() will return > true, so the VDO target not providing ti->type->merge causes this issue. > > Please file a BZ at bugzilla.redhat.com against VDO and I'll continue to > work with the VDO developers to get this fixed for you for RHEL7.5, etc. > > Thanks, > Mike >
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