BugCast BBC#8695: data LOSS on migrate

[p...@citylink.dinoex.sub.org]

Hello all,

   and welcome to the BugCast of today!

Today we are concerned with Your data. With Your data that is probably LOST. At least if You use Migrate jobs and not only Full backups.,

Lets have a look at the matter. Lets imagine we do Full backup at the 1st of month, and Differential every Saturday. Then we have:

Apr  1 2020   Full

Apr  4 2020   Differential since Apr 1

Apr 11 2020   Differential since Apr 1

Each of the differential backups should contain all the data that has changed since the last Full backup, that is, since Apr 1st.

But then, on April 16, we do run a Migration job, to move some very old Full backups to LongTerm Storage. And now it looks that way:

Apr  1 2020   Full

Apr  4 2020   Differential since Apr 1

Apr 11 2020   Differential since Apr 1

Apr 16 2020   Full Migrate of some old stuff

Apr 18 2020   Differential since Apr 16

Apr 25 2020   Differential since Apr 16

As you can see, any Migrate job moving some very old stuff will be considered the "last Full backup", and the next Differential run will contain ONLY the data that has changed AFTER THAT MIGRATE.

So, in this case, all the data that You have changed between Apr 11 and App 16, is LOST.

It is entirely lost, and if Your disk crashes before the end of the month, You will never see that data again.

Now, You have been warned.

This Bug could be fixed. But, obviousely, that must be applied BEFORE Your disk crashes.

Good luck, and Stay tuned for the next BugCast!

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Footnotes:
 * Bug numbers have been randomized for security reasons.
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