Problem with dump(8)

[utzoo!watmath!dmmartindale]

We've also seen the garbage block numbers when dumping an active file system.
The best explanation I can come up with is that the inode gets reallocated
(or just truncated and rewritten) during the period it is getting dumped,
and the copy of the inode (or a double-indirect block) in dump's memory which
points to an indirect block on disk is thus out of date.  Now, if this
stale inode points to a disk block as an indirect block when in fact it's
been reallocated as a data block, you'll get garbage when using its contents
as block pointers.  The few times this has happened here, we've aborted
the dump and restarted it, and it has always worked fine the second time.
(Although it's painful having to restart a 6-reel dump.)

	Dave Martindale