qemu/tests/qemu-iotests/223.out
Eric Blake a1532a225a iotests: New test 223 for exporting dirty bitmap over NBD
Although this test is NOT a full test of image fleecing (as it
intentionally uses just a single block device directly exported
over NBD, rather than trying to set up a blockdev-backup job with
multiple BDS involved), it DOES prove that qemu as a server is
able to properly expose a dirty bitmap over NBD.

When coupled with image fleecing, it is then possible for a
third-party client to do an incremental backup by using
qemu-img map with the x-dirty-bitmap option to learn which parts
of the file are dirty (perhaps confusingly, they are the portions
mapped as "data":false - which is part of the reason this is
still in the x- experimental namespace), along with another
normal client (perhaps 'qemu-nbd -c' to expose the server over
/dev/nbd0 and then just use normal I/O on that block device) to
read the dirty sections.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180702191458.28741-3-eblake@redhat.com>
Tested-by: John Snow <jsnow@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
2018-07-02 19:50:37 -05:00

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QA output created by 223
=== Create partially sparse image, then add dirty bitmap ===
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=4194304
wrote 2097152/2097152 bytes at offset 1048576
2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
Testing:
QMP_VERSION
{"return": {}}
{"return": {}}
{"return": {}}
{"return": {}}
{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false}}
=== Write part of the file under active bitmap ===
wrote 2097152/2097152 bytes at offset 2097152
2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
=== End dirty bitmap, and start serving image over NBD ===
{"return": {}}
{"return": {}}
{"return": {}}
{"return": {}}
{"return": {}}
{"return": {}}
=== Contrast normal status with dirty-bitmap status ===
read 1048576/1048576 bytes at offset 0
1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
read 1048576/1048576 bytes at offset 1048576
1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
read 2097152/2097152 bytes at offset 2097152
2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
[{ "start": 0, "length": 1048576, "depth": 0, "zero": true, "data": false},
{ "start": 1048576, "length": 3145728, "depth": 0, "zero": false, "data": true}]
[{ "start": 0, "length": 2097152, "depth": 0, "zero": false, "data": true},
{ "start": 2097152, "length": 2097152, "depth": 0, "zero": false, "data": false}]
=== End NBD server ===
{"return": {}}
{"return": {}}
{"return": {}}
*** done