iwconvert

sara

I have been reading the documentation on the backing store conversion but some options to the iwconvert command are not quite clear to me.

The documentation states:”If you decide to convert only certain editions, remember that anytime you skip an edition, the next edition will be copied new. For example, if you convert edition 1, 2, and 3, then iwconvert will copy all of edition 1, and then copy differences between 1 and 2, and finally copy differences between 2 and 3. If you subsequently convert edition 9 and 10, then iwconvert will copy all of edition 9 (which will take just as long as copying edition 1 did), and then copy only the differences between 9 and 10.”

The CLT documentation states:
C: Cleans up the history information of a previously converted backing store. Requires that -o is also specified.
This iwconvert step must be performed last, as a separate step, because it may have interbranch dependencies. Note that this action may safely be executed multiple times.
F: Forces a full clone of each edition without the history of submit events for the editions. Use this option if there are gaps in the set of editions that you are converting, or if you do not want to save the submit history.


1. What means “cleans up history information”?
2. Is there a difference in the history information of the files, and the history of the submit events, or do the Submit events contain the deltas of the file versions?

3. What to do to result with a limited set of editions, but with the history information (so users can revert a file to an old version)?
Is a iwrmed the only option? This way we can remove all intermediate editions before the conversion (and convert only the needed editions), or we can remove the intermediate editions after conversion of all editions. The userguide states that the Submit Log entries will be transferred to the next most recent edition. If the deleted edition is the newest one, the Submit Log entries will be transferred to the Staging Area.
4. Does an edition contain the file differences compared to the previous version, or to the Staging Area? In the first option, the edition with the first occurrence of the file contains the file, and all others only contain the difference, so does the Staging Area. In the other option all editions must be updated when a user submits a new version to compute the difference compared to the new version.

Thanks,
Sara

Migrateduser

Sara,
1. When a copy to area is done, this results in some metadata information being stored in the backing store which indicates when the file was copied from etc. So when you look at the history of the file (the copied file) there will be a tag saying "Copied from ...". This is referred to as second predecessor information in the server. Now when converting since branches can be copied over independent of one another, it is quite possible that iwconvert does not have all the information necessary to fixup this second precedessor links. So when it encounters this second predecessor info in the source backing store, it writes it out in a file in the target backing store. The iwconvert -c operation will read this file and fix up the second predecessor information. The iwconvert -c should be the last step, because it needs to happen after all the necessary branches have been converted. If a particular branch has not been converted, the "Copied from ...." info will not be shown.

2. A submit event contains all the files that were submitted as part of that particular submit. So each (submitted) version of a file is associated with a particular submit event.

3. If you wish to have complete version history of all files, then you would have to convert all the editions and then selectively delete some editions. However if a particular version of a file is present only in one edition and that edition happens to be deleted, then the corresponding version of the file will also disappear.

4. A clarification for this point. File versions do not share any data. So if a file has two versions and the only difference between the two version is a single line in a file, each version will have its own copy of the file. That being said, the difference displayed when looking at the file history of a file in a particular edition is the diff with the file's previous version and not with STAGING.

I hope this clears some of your questions.