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<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#44546A">Correct, it by design. Swift doesn’t expect people to delete things “under the covers”. When the auditor finds a corrupted file, it’s the one that quantities it and knows
that it also needs to invalidate the hashes.pkl file. This mechanism is there to minimize extra ‘stuff’ going on both at the node and on the cluster when it comes to making sure there is durability in the system.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#44546A"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#44546A">Wrt why the replication code seems to work if you delete just a .data (again, you shouldn’t do this as files don’t just disappear, the intention is that the auditor is in charge
here) is because of some code in the replicator that I didn’t ‘mimic’ in the reconstructor and it doesn’t look like clay did either when he worked on it. Not really sure it was there – forces a listing every 10 passes for some reason. Clay? (see do_listdir
in update() in the replciator)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#44546A"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#44546A">Thx<br>
Paul<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#44546A"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Changbin Liu [mailto:changbin.liu@gmail.com]
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<b>Sent:</b> Wednesday, July 22, 2015 12:24 PM<br>
<b>To:</b> OpenStack Development Mailing List (not for usage questions)<br>
<b>Subject:</b> Re: [openstack-dev] [Openstack] [Swift] Erasure coding reconstructor doesn't work<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks, Paul and Clay. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">By "deleted one data fragment" I meant I "rm" only the data file. I did not delete the hashes.pkl file in the outer directory. <o:p></o:p></p>
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<p class="MsoNormal">I tried it again. This time deleting both the data file and the hashes.pkl file. The reconstructor is able to restore the data file correctly.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">But now I wonder: is it "by design" that EC does not handle an accidental deletion of just the data file? Deleting both data file and hashes.pkl file is more like a deliberately-created failure case instead of a normal one. To me Swift
EC repairing seems different from the triple-replication mode, where you delete any data file copy, it will be restored. <o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Thanks<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Changbin<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Tue, Jul 21, 2015 at 5:28 PM, Luse, Paul E <<a href="mailto:paul.e.luse@intel.com" target="_blank">paul.e.luse@intel.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri","sans-serif";color:#44546A">I was about to ask that very same thing and, at the same time, if you can indicate if you’ve seen errors in any logs
and if so please provide those as well. I’m hoping you just didn’t delete the hashes.pkl file though
</span><span style="font-family:Wingdings;color:#44546A">J</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri","sans-serif";color:#44546A"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri","sans-serif";color:#44546A">-Paul</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Clay Gerrard [mailto:<a href="mailto:clay.gerrard@gmail.com" target="_blank">clay.gerrard@gmail.com</a>]
<br>
<b>Sent:</b> Tuesday, July 21, 2015 2:22 PM<br>
<b>To:</b> OpenStack Development Mailing List (not for usage questions)<br>
<b>Subject:</b> Re: [openstack-dev] [Openstack] [Swift] Erasure coding reconstructor doesn't work</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">How did you "<span style="font-size:9.5pt">deleted one data fragment"?</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:9.5pt">Like replication the EC consistency engine uses some sub directory hashing to accelerate replication requests in a consistent system - so if you just
rm a file down in an hashdir somewhere you also need to delete the hashes.pkl up in the part dir (or call the invalidate_hash method like PUT, DELETE, POST, and quarantine do)</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:9.5pt">Every so often someone discusses the idea of having the auditor invalidate a hash after "long enough" or take some action on empty hashdirs (mind the
races!) - but its really only an issue when someone delete's something by hand so we normally manage to get distracted with other things.</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:9.5pt">-Clay</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Tue, Jul 21, 2015 at 1:38 PM, Changbin Liu <<a href="mailto:changbin.liu@gmail.com" target="_blank">changbin.liu@gmail.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Folks,<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">To test the latest feature of Swift erasure coding, I followed this document (<a href="http://docs.openstack.org/developer/swift/overview_erasure_code.html" target="_blank">http://docs.openstack.org/developer/swift/overview_erasure_code.html</a>)
to deploy a simple cluster. I used Swift 2.3.0.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I am glad that operations like object PUT/GET/DELETE worked fine. I can see that objects were correctly encoded/uploaded and downloaded at proxy and object servers. <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">However, I noticed that swift-object-reconstructor seemed don't work as expected. Here is my setup: my cluster has three object servers, and I use this policy:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">[storage-policy:1]<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">policy_type = erasure_coding<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">name = jerasure-rs-vand-2-1<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">ec_type = jerasure_rs_vand<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">ec_num_data_fragments = 2<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">ec_num_parity_fragments = 1<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">ec_object_segment_size = 1048576<o:p></o:p></p>
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<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">After I uploaded one object, I verified that: there was one data fragment on each of two object servers, and one parity fragment on the third object server. However, when I deleted
one data fragment, no matter how long I waited, it never got repaired, i.e., the deleted data fragment was never regenerated by the swift-object-reconstructor process.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">My question: is swift-object-reconstructor supposed to be "NOT WORKING" given the current implementation status? Or, is there any configuration I missed in setting up swift-object-reconstructor?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thanks<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:#888888"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:#888888">Changbin</span><o:p></o:p></p>
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