More oddity: retrying several times, the merge-diff sometimes works and sometimes does not, using the same source files.
On Wed, Dec 9, 2015 at 10:15 PM, Alex Gorbachev <a...@iss-integration.com> wrote: > Hi Josh, looks like I celebrated too soon: > > On Wed, Dec 9, 2015 at 2:25 PM, Josh Durgin <jdur...@redhat.com> wrote: > >> This is the problem: >> >> http://tracker.ceph.com/issues/14030 >> >> As a workaround, you can pass the first diff in via stdin, e.g.: >> >> cat snap1.diff | rbd merge-diff - snap2.diff combined.diff > > > one test worked - merging the initial full export (export-diff with just > one snapshot) > > but the second one failed (merging two incremental diffs): > > root@lab2-b1:/data/volume1# cat scrun1-120720151502.bck | rbd merge-diff > - scrun1-120720151504.bck scrun1-part04.bck > Merging image diff: 13% complete...failed. > rbd: merge-diff error > > I am not sure how to run gdb in such scenario with stdin/stdout > > Thanks, > Alex > > > >> >> >> Josh >> >> >> On 12/08/2015 11:11 PM, Josh Durgin wrote: >> >>> On 12/08/2015 10:44 PM, Alex Gorbachev wrote: >>> >>>> Hi Josh, >>>> >>>> On Mon, Dec 7, 2015 at 6:50 PM, Josh Durgin <jdur...@redhat.com >>>> <mailto:jdur...@redhat.com>> wrote: >>>> >>>> On 12/07/2015 03:29 PM, Alex Gorbachev wrote: >>>> >>>> When trying to merge two results of rbd export-diff, the >>>> following error >>>> occurs: >>>> >>>> iss@lab2-b1:~$ rbd export-diff --from-snap autosnap120720151500 >>>> spin1/scrun1@autosnap120720151502 >>>> /data/volume1/scrun1-120720151502.bck >>>> >>>> iss@lab2-b1:~$ rbd export-diff --from-snap autosnap120720151504 >>>> spin1/scrun1@autosnap120720151504 >>>> /data/volume1/scrun1-120720151504.bck >>>> >>>> iss@lab2-b1:~$ rbd merge-diff >>>> /data/volume1/scrun1-120720151502.bck >>>> /data/volume1/scrun1-120720151504.bck >>>> /data/volume1/mrg-scrun1-0204.bck >>>> Merging image diff: 11% complete...failed. >>>> rbd: merge-diff error >>>> >>>> That's all the output and I have found this link >>>> http://tracker.ceph.com/issues/12911 but not sure if the patch >>>> should >>>> have already been in hammer or how to get it? >>>> >>>> >>>> That patch fixed a bug that was only present after hammer, due to >>>> parallelizing export-diff. You're likely seeing a different >>>> (possibly >>>> new) issue. >>>> >>>> Unfortunately there's not much output we can enable for >>>> export-diff in >>>> hammer. Could you try running the command via gdb to figure out >>>> where >>>> and why it's failing? Make sure you have librbd-dbg installed, then >>>> send the output from gdb doing: >>>> >>>> gdb --args rbd merge-diff /data/volume1/scrun1-120720151502.bck \ >>>> /data/volume1/scrun1-120720151504.bck >>>> /data/volume1/mrg-scrun1-0204.bck >>>> break rbd.cc:1931 >>>> break rbd.cc:1935 >>>> break rbd.cc:1967 >>>> break rbd.cc:1985 >>>> break rbd.cc:1999 >>>> break rbd.cc:2008 >>>> break rbd.cc:2021 >>>> break rbd.cc:2053 >>>> break rbd.cc:2098 >>>> run >>>> # (it will run now, stopping when it hits the error) >>>> info locals >>>> >>>> >>>> Will do - how does one load librbd-dbg? I have the following on the >>>> system: >>>> >>>> librbd-dev - RADOS block device client library (development files) >>>> librbd1-dbg - debugging symbols for librbd1 >>>> >>>> is librbd1-dbg sufficient? >>>> >>> >>> Yes, I just forgot the 1 in the package name. >>> >>> Also a question - the merge-diff really stitches the to diff files >>>> together, not really merges, correct? For example, in the following >>>> workflow: >>>> >>>> export-diff from full image - 10GB >>>> export-diff from snap1 - 2 GB >>>> export-diff from snap2 - 1 GB >>>> >>>> My resulting merge export file would be 13GB, correct? >>>> >>> >>> It does merge overlapping sections, i.e. part of snap1 that was >>> overwritten in snap2, so the merged diff may be smaller than the >>> original two. >>> >>> Josh >>> >> >> >
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