scott@thirdi.uucp (Scott Southard) (11/08/90)
We are currently dumping our filesystems to an Exabyte tape drive nightly,
and assuming that if dump gives no errors the dump was successful. I have
some doubts as to whether this is alway true, and would like to examine
the tape (without restoring the contents to disk) to determine whether the
tape is indeed ok. Does anyone know of any utilities for verifying the
consistency of a dump tape? The 't' option to the restore program may
uncover errors in the table of contents, but I'm doubtful whether a
successful read of the table of contents indicates a completely consistent
dump. How do other people deal with this problem? Has anyone out there
ever seen a case where dump succeeded but a restore of the dump tape
failed?
I'm using a Sun SPARCstation 1 running SunOS4.03.
--
Scott Southard scott@thirdi or, for stupid mailers:
Third Eye Software, Inc. {pyramid,sun,apple,hpda}!thirdi!scottchris@mimsy.umd.edu (Chris Torek) (11/09/90)
In article <1990Nov8.004559.3904@thirdi.uucp> scott@thirdi.uucp (Scott Southard) writes: >Does anyone know of any utilities for verifying the consistency of a >dump tape? We just had a big discussion on this in this very newsgroup, under the subject `why idle backups'. Whether a tape can be `verified' depends on your definition of `verify' and how much time and effort you are willing to expend. If you can take the file system offline (either by unmounting or by running single-user) you could write a program to compare a dump to the actual contents of a file system. I know of no such utility (though it would be useful, e.g., before moving a lab like we did here a few years ago). -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 405 2750) Domain: chris@cs.umd.edu Path: uunet!mimsy!chris
williams@nssdcs.gsfc.nasa.gov (Jim Williams) (11/10/90)
In article <27542@mimsy.umd.edu> chris@mimsy.umd.edu (Chris Torek) writes: >In article <1990Nov8.004559.3904@thirdi.uucp> >scott@thirdi.uucp (Scott Southard) writes: >>Does anyone know of any utilities for verifying the consistency of a >>dump tape? > [text deleted] >I know of no such utility (though it would be useful, e.g., before >moving a lab like we did here a few years ago). >-- >In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 405 2750) >Domain: chris@cs.umd.edu Path: uunet!mimsy!chris The dump command under SunOS 4.1 has the following option. I haven't used this yet, so I can't comment on it's utility. v After writing each volume of the dump, the media is rewound and is verified against the filesystem being dumped. If any discrepancies are found, dump will respond as if a write error had occurred; the operator will be asked to mount new media, and dump will attempt to rewrite the volume. Note that any change to the filesystem, even the update of the access time on a file will cause the verification to fail. Thus, the verify option can only be used on a quiescent filesystem. Spoken: Jim Williams Domain: williams@nssdcs.gsfc.nasa.gov Phone: +1 301 286-4405 UUCP: uunet!mimsy!williams USPS: NASA/GSFC, Code 633, Greenbelt, MD 20771 Motto: There is no 'd' in "kluge"! It rhymes with "huge", not "sludge".
greg@cheers.Bungi.COM (Greg Onufer) (11/12/90)
chris@mimsy.umd.edu (Chris Torek) writes: >In article <1990Nov8.004559.3904@thirdi.uucp> >scott@thirdi.uucp (Scott Southard) writes: >>Does anyone know of any utilities for verifying the consistency of a >>dump tape? > [[ ... ]] >I know of no such utility (though it would be useful, e.g., before >moving a lab like we did here a few years ago). SunOS 4.1 dump does exactly what you want. It will fail, though, if *anything* on the filesystem changes (ie, file access times), the verify will fail. Cheers!greg