On Fri, Oct 30, 2020 at 09:12:46PM +0000, Martin Wilck wrote: > On Fri, 2020-10-23 at 16:15 -0500, Benjamin Marzinski wrote: > > Only rdac arrays support 0xC9 vpd page inquiries. All other arrays > > will > > return a failure. Since all rdac arrays in the the built-in device > > configuration explicitly set the RDAC path checker, and almost all > > other > > scsi arrays do not set a path checker, it makes sense to only do the > > rdac inquiry when detecting array capabilities if the array's path > > checker is explicitly set to rdac. > > > > Multipath was doing the check if either the path checker was set to > > rdac, or no path checker was set. This means that for almost all > > non-rdac arrays, multipath was issuing a bad inquiry. This was > > annoying > > users. > > This is sort of funny. We created the entire check_rdac() feature in > order to autodetect RDAC arrays. If we limit the autodetection to those > arrays that have "rdac" set already, why would we do this at all? We > could simply go with the hwtable / config file settings, as we used to > before check_rdac() was created. All we'd need to do is use "alua" prio > for arrays with "rdac" checker. What am I missing here? > > I thought that this autodetection was intended because there are many > Netapp OEMs which we may not all have included in the hwtable (thus > having no path_checker set). For those, we'd choose the wrong settings > by default with this patch, only to avoid some error messages about > unsupported VPDs. I'm not convinced that that's a good idea. > > Suggestion: we could try to retrieve VPD 0 (supported VPDs) before > checking VPD 0xc9. That would avoid the errors on non-Netapp hardware, > while still allowing us to autodetect RDAC systems that are missing in > the hwtable. When this idea was brought up in discussions about how to solve this, there was a worry that older rdac devices might not not support vpd page 0 correctly. I'm not sure how valid that worry is. -Ben > > Regards > Martin > > > > > Cc: Steve Schremmer <sschremm@xxxxxxxxxx> > > Cc: NetApp RDAC team <ng-eseries-upstream-maintainers@xxxxxxxxxx> > > Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx> > > --- > > libmultipath/propsel.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c > > index fa4ac5d9..90a77d77 100644 > > --- a/libmultipath/propsel.c > > +++ b/libmultipath/propsel.c > > @@ -501,7 +501,7 @@ check_rdac(struct path * pp) > > if (pp->bus != SYSFS_BUS_SCSI) > > return 0; > > /* Avoid ioctl if this is likely not an RDAC array */ > > - if (__do_set_from_hwe(checker_name, pp, checker_name) && > > + if (!__do_set_from_hwe(checker_name, pp, checker_name) || > > strcmp(checker_name, RDAC)) > > return 0; > > len = get_vpd_sgio(pp->fd, 0xC9, 0, buff, 44); > > -- > Dr. Martin Wilck <mwilck@xxxxxxxx>, Tel. +49 (0)911 74053 2107 > SUSE Software Solutions Germany GmbH > HRB 36809, AG Nürnberg GF: Felix > Imendörffer > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
