Le jeudi 17 avril 2008 à 22:55 +0200, Christophe Varoqui a écrit : > Notice to reader : real questions are hidden in this obfuscated > message ! I'll mark them with ** to augment the chances for them being > answered :) > > Path checker maintainers, > > ** would you object to my changing the checkers open() flags from O_RDWR > to O_RDONLY ? ** Directio and readsector0 would not object, and all > other checkers use the file descriptor to submit SG_IO ioctls which do > not require Write capability. > Re-reading the SG documentation at http://sg.torque.net/sg/sg_io.html, I > understand it should be ok. In real life, scsi_id does exactly that for > example. > Please disregard this first part : O_RDONLY is already the flag use in libmultipath/discovey.c > The particular issue I'm facing is that on a RHEL5 box presented with > EMC Symmetrix R2 Logical Units (write-protected LU receiving SRDF > updates from R1 LU), the checker bails out on open(/dev/sd?, O_RDWR| > O_NONBLOCK) returning EROFS. opening with O_RDONLY grants us a usable > fd, which give the checker a chance to report the actual path state. > > I'd like to fix the checker inconsistency, but we'll hit another wall > short after that : because the device mapper refuses to honor the > R2-multipath-tables loading without the read-only devmap option. > > This behavior is new to RHEL5. R2 LU could perfectly be multipathed in > RHEL4. > ** Does someone have insight about this new kernel behaviour, and about > the multipath layer desired behaviour in this context ? ** I personnaly > would rather not care for promoting a devmap from RO to RW upon R1-R2 > split, and the even more tricky demoting from RW to RO (what about io > flush ?) upon un-spliting. > > Regards, > cvaroqui -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
