On Tue, 2007-05-22 at 13:23 +0530, Manoj Joseph wrote: > Kalpak Shah wrote: > > >> Also, I am curious about this. Is there a test case for mounting the > >> same filesystem multiple times? Does this use different paths to reach > >> the device? Or is there a race? Or does it happen on a device shared by > >> multiple hosts? > >> > > > > If you are using some HA software, there is the possibility of a race. > > Yes it can happen on a device shared by multiple hosts. > > Ah, if the HA-software doesn't deal with multiple mounts for filesystems > it is managing, then I would claim that the software is flawed. :) Well, it is known to happen so it wouldn't be bad to make sure. > > But yes, turning on MMP would help. > > It might also help to make the frequency at which sequence number gets > updated (currently 5 sec) tunable. Would making that also a field in the > super block be a bad idea (set only by mkfs/tunefs)? Updating the MMP sequence too often would hurt the filesystem performance. > > It might also be worthwhile to write the dev_t, the path of the device > and the hostname to the s_mmp_block, along with the random sequence. (I > assume there is enough space.) If the mount is being failed because of a > multiple mount scenario, these fields could be used to provide useful > diagnostics. Yes, the dev_t, host name, the sequence and the time last updated would all be printed. There is lots of space since we have an entire block. > My $ 0.02. :) Thanks. :) > > Regards, > Manoj - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
