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You need to understand that there are two separate concepts of
"expiration" with ABS (layered upon MDMS).
ABS has retention period which means how long the catalog entries are
kept before it expires. You set retention time to 3 days, that means
after 3 days from backup your file sys$login:login.com;1, you cannot
restore this file or perform lookup. The catalog entry is expired.
This retention time has nothing to do with when the tape itself is
recycled.
In MDMS volume record, you see "scratch date". That is the date when
the VOLUME is deallocated (means gets recycled). On the scratch date,
the VOLUME goes into either TRANS or FREE state depending on FRESTA of
tapestart.com.
It is the user's responsibility to set the scratch date of volume so
that all catalog entries corresponding to the files save in that
particular volume are expired prior to the scratch date.
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In your example, no, we do not reuse the space of the tape. The tape
does not get reused until the scratch date of the volume. (In your
example, I don't know the scratch date). After the scratch date,
(and after the tape goes into FREE state), ABS reuse the whole tape.
ABS initialize the tape and start writing from the beginning.
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ABS will fill the tape as much as possible and ask for more tape when
more space is needed. ABS will stall and wait until it can find a tape
that matches the criteria (until the user makes another tape available
for ABS to select). ABS does not pre-determine the size of total backup
VS. the space of the tape available. It will use whatever is available
and ask for more when needed.
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Thanks,
Masami
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