On Wed, Jun 06, 2018 at 10:25:36PM +0200, Martin Wilck wrote: > On Fri, 2018-06-01 at 17:22 -0500, Benjamin Marzinski wrote: > > Some arrays, such as the EMC VNX, don't follow the scsi persistent > > reservations spec in making key registrations per I_T NEXUS. Instead, > > the registration is shared by all target ports connected to a given > > host. This causes mpathpersist to fail whenever it tries to register > > a > > key, since it will receive a registration conflict on some of the > > paths. > > > > To deal with this, mpathpersist needs to track the hosts that it has > > done a registration on, and only register once per host. The new > > "all_tg_pt" multipath.conf option is used to set which arrays need > > this > > feature. I currently don't know if all EMC VNX arrays handle > > persistent > > reservations like this, or if it is configurable. A future patch will > > update the VNX built-in config, if this is indeed their default (or > > only) setting. > > > > Multipathd doesn't need to worry about this. It is often the case > > that > > when a path device comes back, it will still have the keys registered > > to > > it. Because of this, multipathd uses register-and-ignore, which means > > that it won't cause an error if the registration has already happened > > down a different target port. > > > > Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx> > > --- > > libmpathpersist/mpath_persist.c | 28 ++++++++++++++++++++++------ > > libmultipath/config.c | 2 ++ > > libmultipath/config.h | 2 ++ > > libmultipath/defaults.h | 1 + > > libmultipath/dict.c | 10 ++++++++++ > > libmultipath/propsel.c | 15 +++++++++++++++ > > libmultipath/propsel.h | 1 + > > libmultipath/structs.h | 7 +++++++ > > multipath/multipath.conf.5 | 11 +++++++++++ > > 9 files changed, 71 insertions(+), 6 deletions(-) > > The patch looks good to me, but doesn't this mean that mpathpersist > would now also support persistent reservations with the ALL_TG_PT bit > set (IIUC, the VNX basically acts as if that bit was always set)? > > If yes, I think the warning in mpath_prout_reg() about this flag could > be dropped, and mpathpersist could be extended to support the -Y/ > --param-alltgpt option, no? I'm a little fuzzy on the --param-alltgpt option. The initial mpathpersist sumbission didn't include support for it, on the grounds that supporting it would cause mpathpersist to do a lot of extra work. What I did cuts down on the amout of work that mpathpersist has to do. If I could clear that up, I'd happily add the option to mpathpersist. -Ben > > Otherwise, I'd suggest to give this option a different name, because > it'd just too easily be confused with ALL_TG_PT from the spec. > > Regards, > Martin > > -- > Dr. Martin Wilck <mwilck@xxxxxxxx>, Tel. +49 (0)911 74053 2107 > SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton > HRB 21284 (AG Nürnberg) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
