Difference between revisions of "FAQ"

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* <b>Q</b>: Why does dump fail with "Cannot dump half of a stream unix connection" message in logs?
 
* <b>Q</b>: Why does dump fail with "Cannot dump half of a stream unix connection" message in logs?
 
* <b>A</b>: There are configurations [[when C/R fails]]. This particular error is about [[external UNIX socket]].
 
* <b>A</b>: There are configurations [[when C/R fails]]. This particular error is about [[external UNIX socket]].
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* <b>Q</b>: Why does restore fail with "... pid mismatch ..." error in logs?
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* <b>A</b>: The PID of the process of thread CRIU tries to restore is already busy. To overcome this, try [[CR in namespace]].
  
 
[[Category: HOWTO]]
 
[[Category: HOWTO]]
 
[[Category: Under the hood]]
 
[[Category: Under the hood]]

Revision as of 09:20, 29 September 2016

The intention of this page is to hold answers to frequently (and no so frequently) asked questions as well as some random data spread among developers' heads ;-)

  • Q: Why CRIU dumps parts of read-only mappings that map the code section of a binary? For instance, there is a mapping at, say 0x400000, that maps the code of /usr/bin/something. After dump there will be at least a page at 0x400000 in the pagemap
  • A: The code section may have been COWed, for instance during dynamic load of the shared libraries.


  • Q: Why my test cannot do privileged operation, though I run zdtm.py as root?
  • A: That's because zdtm.py runs all sub-tests from non-existing non-root user. If you need root prio in your sub-test add 'flags': 'suid' into test's .desc file.


  • Q: Is it possible to do live migration from one server to another with changing the IP address?
  • A: Quick answer is -- if breaking the connections is OK, then yes. In details it's described in this article.


  • Q: Why does dump fail with "Cannot dump half of a stream unix connection" message in logs?
  • A: There are configurations when C/R fails. This particular error is about external UNIX socket.


  • Q: Why does restore fail with "... pid mismatch ..." error in logs?
  • A: The PID of the process of thread CRIU tries to restore is already busy. To overcome this, try CR in namespace.