James Pearson wrote: >>>Could it be that the partition table has become corrupt (e.g. >>>overwritten)? >> >> But everything seems to be working perfectly; >> is that possible if the partition table is corrupt? > > Yes - the partition table may have been fine when the various file > systems were mounted - which could be why all looks OK now. However, if > you were to reboot, you may have problems ... > > Make sure you have backups before doing any changes to the partition > table. Yes, I think I backup everything important every night, with BackupPC. What is strange is that I don't recall any episode that might have corrupted the partition table. I run smartd on this machine; and according to "sudo smartctl -a /dev/sdb" everything seems fine with this drive, no errors reported. (I'm a bit wary of running "smartctl -t" as I'm not in the same country as the machine at the moment.)