Francis,
I believe that an AUDIT VOLUME will also lock the volume, although you are
correct that it only uses one drive instead of two (as a MOVE DATA would).
Perhaps IBM could add an option to AUDIT VOLUME which would cause all data
blocks to be read on the tape? In the meantime, an AUDIT VOLUME probably
does a better job than nothing at all. My understanding is that for small
files, the file data will end up being in the same "tape block" (?) as file
header info, so you will end up verifying that the tape block is at least
readable (which may be good enough, especially if the tape device has built-
in CRC checking).
I think the only way to guarantee that the tape is still readable is to
actually do a MOVE DATA on the tape volume.
If it is any consolation, many tape problems show up as recoverable errors
before the end up being unrecoverable errors. We have a policy of getting
rid of any tapes that have any kind of read or write errors as soon as
possible. We had lots of problems with our 8mm tapes, but none (so far)
with our new DLT4000 drives. (I'm knockin on wood!)
..Paul
--
On Tue, 20 Aug 1996 22:06:48 +0100 Francis Dequenne said:
On Tue, 20 Aug 1996 22:06:48 +0100 Francis Dequenne said:
>Ah.
>
>This is a blow.
>
>The obvious next question is "What can I use to make sure that my tapes are
>usable? ". Considering that one day, we will have terrabytes worth of tape
>archives, here, we can not really play at a game of moving data and locking
>multiple drives every time that a problem is reported on a drive or media, just
>to make sure that we have not loss anything.
>
>On good old MVS, I had 3rd party products like FATS/FATAR that allowed me to
>make a tape scan and possibly recover some data out of damaged volumes.
>
>Is anybody aware of something comparable on AIX platforms, especially for
>magstar medias?
>
>(Software producers, there is a market here! )
>
>Cheers.
>On Aug 20, 2:54pm, Paul Zarnowski wrote:
><=> Subject: Re: Does audit actually check data integrity?
><=>No, an audit does not guarantee integrity of the data stored on a tape.
><=>I also had this misconception. An audit validates file information stored
><=>in the database with that stored on the tape. It does not actually check
><=>to see that the file data itself is readable and correct. We discovered
><=>this when an audit volume revealed no problems, yet a move data failed.
><=>..Paul
><=>--
><=>On Tue, 20 Aug 1996 13:44:46 -0400 Tim Dobrowolsky said:
><=>>When an Audit is performed on a tape volume, what exactly does ADSM check?
><=>>Does it just check
><=>>to see if it can find the stored file, or is there a checksum stored in the
><=>>database that is
><=>>checked against the tape file? What I'm really wondering is whether a
><=>>successful audit guarantees
><=>>the integrity of the data stored on a tape. Thanks.
><=>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
><=>>> Tim Dobrowolsky > < yksloworboD miT <
><=>>> Computer Services > < secivreS retupmoC <
><=>>> Catonsville Community College > < egelloC ytinummoC ellivsnotaC <
><=>>> tim AT catrs.cat.cc.md DOT us > <
>su.dm.cc.tac.srtac@mit <
><=>>> 410-455-4562 > < 2654-554-014 <
><=>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
><=> End of excerpt from Paul Zarnowski
>
>
>
>--
>Regards
>
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