Upgrade from 1.4 to 1.5.3 (vault v6 to 7): some files have their last modified timestamps changed to time of upgrade

Software

  • Windows 10 build 19041 (amd64)
  • Cryptomator 1.4.15 (vault version 6), upgraded to Cryptomator 1.5.3 (vault version 7)
  • Dokany as installed by Cryptomator
  • Google Drive File Stream 40.0.8.0 (no local file copies, online only)

Description
After availability of Cryptomator 1.5.3 on April 30, 2020 I migrated on May 6. The upgrade log looked fine:

23:44:58.263 [App Background Thread 003] INFO o.c.c.migration.v7.Version7Migrator - Upgrading G:\Mijn Drive\ENCRYPTED from version 6 to version 7.
23:44:58.516 [App Background Thread 003] INFO o.c.c.migration.v7.Version7Migrator - Backed up masterkey from masterkey.cryptomator to masterkey.cryptomator.381AB259.bkup.
23:44:58.653 [App Background Thread 003] INFO o.c.c.migration.v7.Version7Migrator - Underlying file system meets filename length requirements.
23:45:00.816 [App Background Thread 003] INFO o.c.c.migration.v7.Version7Migrator - Starting migration of 16842 files
23:45:00.840 [App Background Thread 003] INFO o.c.c.migration.v7.MigratingVisitor - MOVED G:\Mijn Drive\ENCRYPTED\d\SS\6UV3OBSYJZG4RZQ62E4WG47WXKPSGW\265GDWRUF2PMT34QFCZWATXOFAGXM7D5XMBN5BQ= to G:\Mijn Drive\ENCRYPTED\d\SS\6UV3OBSYJZG4RZQ62E4WG47WXKPSGW\17ph2jQunsnvkCizYE7uKA12fH27At6G.c9r
[deleted: the other log entries]
23:47:04.593 [App Background Thread 003] INFO o.c.c.migration.v7.MigratingVisitor - MOVED G:\Mijn Drive\ENCRYPTED\d\LD\HDKUG2GCWOXR4YOYZ6UM6PE4TU6EDJ\ZYXBDEVZDI772DUZFUNW3SS2AMWVOJYCDLKJGSB6ZI44PGM776DQX5CJXJSOFUYR6J5T65KZEDPKQ7Q= to G:\Mijn Drive\ENCRYPTED\d\LD\HDKUG2GCWOXR4YOYZ6UM6PE4TU6EDJ\zi4RkrkaP_0OmS0bbcpaAy1XJwIa1JNIPso5x5mf_4cL9Em6ZOLTEfJ7P3VZIN6ofg==.c9r
23:47:22.416 [App Background Thread 003] INFO o.c.c.migration.v7.Version7Migrator - Updated masterkey.
23:47:22.416 [App Background Thread 003] INFO o.c.c.migration.v7.Version7Migrator - Upgraded G:\Mijn Drive\ENCRYPTED from version 6 to version 7.

So, that was a migration of a few minutes for >16K files. Nice. Vault opened normally and after checking if files using the virtual drive where present, readable and writable I started production.

Issue
Some time later, I discovered that about 10% of the files had their last modified timestamps changed from their original modification timestamp to the migration time. (Please note that I have not copied the vault to a local drive and copied/moved back to a (new) vault. This was an in situ migration. Also please note i’m not talking about directory time stamps.)
As the Cryptomator upgrade log indicates it is just moving files, one could expect the issue should reside somewhere else, because a file move normally should not change the modification time.

So I have no special reason to suspect Cryptomator, Dokany, Google cloud or Windows. I’m just reporting this here to the possible benefit of the community.

Some details

  • Analysis date: July 1, 2020
  • Total of directories and files: 16.999, dirs 2.008, files 14.991
  • Files modified 06-05-2020: 1.560, other: 13.431
  • Some 06-05-2020 files have been changed after migration, so the count above is a little bit too low.
  • This is a strange observation. Am I blundering or nuts? Could be, but I have a nice backup, so I checked soms random files. Indeed, for every 06-05-2020 file I checked, there exists an older but otherwise identical file, with the same creation date, but with a different modification date.
  • Is there a pattern? Maybe: often (but not always) the files from a complete directory are restamped to 06-05-2020, or not. Most subdirs also.
  • I do not know how to relate real files names to the encrypted named in the upgrade.log. Is there a tool for this?
  • According to the time stamps this issue is interwoven trough the upgrade, not (only) at the beginning or the end.

Something similar was also reported here:

Are the files with modified timestamps still ok? (no changes to the contents or checksum?)

Do you see any pattern to this? For example, do all the modified files have very long file names, or unusual characters not used anywhere else?

Does this affect all the files in a particular folder, or is it more random?

I did a bunch of testing during beta. My experience was file dates were preserved, however folders containing a subfolder lost their time (on the folder - never on the files). 1.5.0beta2 - Large Vault Migraton Feedback

Yes, they are fine.

All I could observe I wrote up under the Some details section in my post.

Yeah, I guess that’s expected.

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