** Description changed:
+ [Impact]
+ It's very easy to accidentally corrupt the backup copy of a file when
resuming an interrupted backup.
+
+ Specifically, there are several ways to end up backing up corrupted
+ data:
+
+ A) If resuming after a volume that ended in a one-block file, we would skip
the first block of the next file.
+ B) If resuming after a volume that ended in a multi-block file, we would skip
the first block of the next file.
+ C) If resuming a non-encrypted backup after a volume that spanned a
multi-block file, we would skip some data inside the file.
+
+ These are all very similar but have slightly different code fixes.
+ Together they amount to "if you resume a backup, it's very likely you
+ will have corrupted data somewhere". The only situation that doesn't is
+ resuming in the middle of a file while using encryption.
+
+ [Test Case]
+ Running the restart test suite from my fix branch, which includes new tests
for these cases:
+ bzr branch lp:~mterry/duplicity/static-corruption
+ cd static-corruption
+ ./testing/run-tests
+
+ [Regression Potential]
+ This patch changes (1) how much data we read from source files when backing
up and (2) how we pick where to resume a backup.
+
+ If a regression did appear because of this branch, I would expect it to
+ be a similar data corruption problem (not starting in the right place or
+ reading too much/too little from source files).
+
+ [Original Report]
I have found a bug similar to #613244.
It seems that some files are corrupted when the backup is interrupted
and resumed when using --no-encryption option.
The make-ctrl-c-test.sh test fails if I add the --no-encryption option
to duplicity. Without this option it works fine.
I have added an option to make-ctrl-c-test.sh test to run it with or
without encryption (patch attached).
I have seen this bug in the current duplicity quantal version
(0.6.19-0ubuntu2) and in the last bazaar revision (897).
I also attached a patch that seems to fix this issue. I don't know
anything about duplicity internals, so I don't know if this patch is
correct or it will break something. Actually, I have ran the run-test
script and it fails in test_GzipWriteFile test. But hopefully this can
help you to fix the problem.
- These are the final log lines of the make-ctrl-c-test.sh script, with and
without encryption.
-
+ These are the final log lines of the make-ctrl-c-test.sh script, with
+ and without encryption.
+
make-ctrl-c-test.sh with encryption:
...
Restoring backups...
Local and Remote metadata are synchronized, no sync needed.
Last full backup date: Mon Dec 17 14:07:59 2012
Local and Remote metadata are synchronized, no sync needed.
Last full backup date: Mon Dec 17 14:08:13 2012
Diff between /lib and /tmp/restore1
Diff between /tmp/restore1 and /tmp/restore2
make-ctrl-c-test.sh with --no-encryption and without fix applied:
...
Restoring backups...
Local and Remote metadata are synchronized, no sync needed.
Last full backup date: Mon Dec 17 14:08:55 2012
Local and Remote metadata are synchronized, no sync needed.
Last full backup date: Mon Dec 17 14:09:16 2012
Diff between /lib and /tmp/restore1
Diff between /tmp/restore1 and /tmp/restore2
Files
/tmp/restore1/modules/3.5.0-19-generic/kernel/drivers/infiniband/hw/qib/ib_qib.ko
and
/tmp/restore2/modules/3.5.0-19-generic/kernel/drivers/infiniband/hw/qib/ib_qib.ko
differ
make-ctrl-c-test.sh with --no-encryption and fix applied:
...
Restoring backups...
Local and Remote metadata are synchronized, no sync needed.
Last full backup date: Mon Dec 17 14:19:43 2012
Local and Remote metadata are synchronized, no sync needed.
Last full backup date: Mon Dec 17 14:20:14 2012
Diff between /lib and /tmp/restore1
Diff between /tmp/restore1 and /tmp/restore2
- The test_GzipWriteFile fails with this error:
+ The test_GzipWriteFile fails with this error:
======================================================================
FAIL: test_GzipWriteFile (__main__.GPGTest)
Test GzipWriteFile
----------------------------------------------------------------------
Traceback (most recent call last):
- File "tests/gpgtest.py", line 135, in test_GzipWriteFile
- assert size - 64 * 1024 <= os.stat("testfiles/output/gzwrite.gz").st_size
<= size + 64 * 1024
+ File "tests/gpgtest.py", line 135, in test_GzipWriteFile
+ assert size - 64 * 1024 <= os.stat("testfiles/output/gzwrite.gz").st_size
<= size + 64 * 1024
AssertionError
----------------------------------------------------------------------
Ran 8 tests in 1.326s
FAILED (failures=1)
Test failed
** Changed in: duplicity
Status: Fix Committed => Triaged
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https://bugs.launchpad.net/bugs/1091269
Title:
Data corruption when resuming
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