On Sat, Feb 21, 2004 at 11:02:35PM +0100, christophe varoqui wrote: > I've got a problem with the new path revalidation method : > The storage controlers I use for testing offer zero valid paths during a > controler switch. I just can't see how such a scenario will handled > correctly : how will the kernel mpath code wait for userspace to > revalidate a path before sending IO errors ? how many paths are on each controller ? > Anyway, given this part works, would you prefer to see the path > revalidation userspace spawn 1 process per multipath or 1 master daemon > plus threads ? I personnaly would vote for the former. I would tend towards the latter, though at this stage do whatever is easiest. > Last question : what is the userspace action needed to revalidate a path > ? new libdevmapper primitive ? No it's got nothing to do with libdevmapper. I suggest your multipath daemon take a config file (maybe borrow the config file code from LVM2?), that specifies programs/scripts to be run to test a path, frequency of testing if the path is believed to be ok, and frequency of retesting for failback. A trivial test script would just try and read sector 0 of the device. - Joe
