On Thu, 2013-09-19 at 15:53 +0100, Orlando Richards wrote: [SNIP]
> Along the way we discovered an odd GPFS "feature" - if some nodes in the > cluster use RDAC (and thus have /dev/sdXX devices) and some use > multipathd (and thus use /dev/dm-XX devices), then the nodes can either > fail to find attached NSD devices (in the case of the RDAC host where > the NSD's were initially created on a multipath host) or can try to talk > to them down the wrong device (for instance - talking to /dev/sdXX > rather than /dev/dm-XX). We just set up this mixed environment to > compare rdac vs dm-multipath, and don't expect to put it into production > - but it's the kind of thing which could end up cropping up in a system > migrating from RDAC to dm-multipath, or vice versa. It seems that on > creation, the nsd is tagged somewhere as either "dmm" (dm-multipath) or > "generic" (rdac), and servers using one type can't see the other. > That is all covered in the GPFS documentation under "don't do that" ;-) [SNIP] > > Thankfully, we have no plans to mix the environment - but for future > reference it could be important (if ever migrating existing systems from > rdac to dm-multipath, for instance). > The recommendation is roughly umount GPFS everywhere, export the file system, change everything to dm-multipath/RDAC depending on your poison, import file system and mount again. I think you can skip the export/import by doing some fiddling to switch the NSD type. JAB. -- Jonathan A. Buzzard Email: jonathan (at) buzzard.me.uk Fife, United Kingdom. _______________________________________________ gpfsug-discuss mailing list gpfsug-discuss at gpfsug.org http://gpfsug.org/mailman/listinfo/gpfsug-discuss
