[lug] lvm and physical volume worries

[Daniel Webb]

The crux of the problem is that if you lose a PV in your LV, you now have a
hole in the filesystem.  I'm not sure what LVM returns to the caller when
those extents are accessed (zeros?  read error?) but I know that it isn't
good.  So the question is then: how does the filesystem you put on your LV
handle large parts of its contents suddenly returning read errors (or zeros,
or whatever)?

With ext2/3, my understanding is that if you lose the beginning of the
filesystem contents, you'll have to do some manual work to fix it using one of
the backup file tables (please comment on this if you actually know what
you're talking about, cause I don't).  If you lose the middle or end, I think
you can just run e2fsck and only lose the parts that were on the dead PV.  But
no guarantees.