Multi Computer Question

[BlacklightJDR]

Hi All,

 

I've got a question regarding how the sync-ing works from the standpoint of the following setup. I want to switch over to this rather than continuing to use dropbox so I can share all my files not just a portion. Anyways here is my setup.

 

Primary Tower computer with about 3TB of storage and NAS with comparable will be on all the time, or at least 1 of them will be (NAS will be on running RAID5 with hotspare if the tower has to be shut off or rebooted).

 

Laptop computer to be used infrequently but wanting to keep mission critical files in unison. But since it may not be used for periods at a time, i'm concerned by the following line in the FAQ

 

BitTorrent Sync will synchronize the file that was the latest added to BitTorrent Sync even if it is not the newest version of the file itself.

 

Does this mean that the next time I turn on/open up the laptop it will write its old version to the sync since from its perspective it is the latest added? Or will it simply fetch the newest version from the other pair running.

 

I don't want to have to set them up so that one of the machines is read only to protect the critical files, as Ideally I want to be able to use the laptop on the road if need be and then have the files updated back to the main machine and backup.

Thanks all!
 

Edited April 15, 2014 by BlacklightJDR

[RomanZ]

@BlacklightJDR,

 

BTSync has a database where it stores service data (like, directory tree and hashes for all the files). It also stores a "change time" for every file and folder. Change time might differ from file's mtime and usually indicates user's operation on the file: deletion, replacing file with the older version, etc. When deciding which file to store, BTSync relies on change time, not on mtime.

 

For example: your sync dir contains a file a.txt, modified on 2014-01-15. It is synced to all your peers. When you add directory to BTSync, change times will be equal to files mtimes. Today, on 2014-04-15 you decide that the synced version is not something that you want, and you replace a.txt with older a.txt modified on 2014-01-01. In this case, BTSync remembers that the change time of a.txt is 2014-04-15 and it is definitely newer than 2014-01-15 of other instances of a.txt on other peers. So BTSync will distribute older file, because you (user) decided that it is more important for you.

[BlacklightJDR]

Ah ok, that helps quite a bit, I'm going to paraphrase it just to make sure I'm understanding this properly.

 

BTSync relies on the ctime of the file, not the files mtime to resolve conflicts, and so in my case since the pair of computer+NAS will have files that have newer ctime's due to the files having being touched by them more recently, the laptop will pick up on that and fetch the newer versions of the file, regardless of whether they are actually newer or not (aka the most recently used version of the file even if its older).

 

That correct?

[RomanZ]

Correct. ctime is stored in BTSync's database - please do not confuse it with file's "Create time", "Modification time", "Access time".