How To Make Bittorrent Sync Really Real-Time?


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I have been using BitTorrent Sync for a while. I've tried many different cloud backup solutions (including several other peer-to-peer backup tools) and finally choose BitTorrent Sync and Dropbox as my cloud backup solutions. Generally speaking, BitTorrent Sync is fast once it starts to synchronize. However, I found quite often that BitTorrent Sync waits for a long time (about 5 to 6 minutes) to start synchronization. As BitTorrent Sync has no reliable way to show synchronization progress on Linux (don't trust the web UI) currently, it is very annoying for me as I constently use multiple computers at the same time. To address this issue, I even wrote a bash script to test whether a local file has been synchronized with the remote one. Dropbox on the contrast is much better on real-time synchronization. Changes on files in the Dropbox folder is almost immediately captured. I wonder whether BitTorrent Sync can do a better job to detect changes faster? Perhaps cache freqently changed files?

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I wonder whether BitTorrent Sync can do a better job to detect changes faster? Perhaps cache freqently changed files?


As Harold has indicated, "real time" sync very much depends upon the host operating system, as not all OS's can detect changes to files instantly.


As a "fall back", Sync has an advanced "folder_rescan_interval" setting that causes Sync to rescan the folders it's monitoring every 600 seconds (10 minutes) by default to pick up those changes that weren't detected in real-time. If your using an OS where updates to the file system are not instantly picked up by Sync, you could lower the "folder_rescan_interval" so that the "fall back" scan occurs more frequently.


Note: If you set this value too low, it could lead to excessive disk/CPU load, as every file/folder being monitored by Sync will be rescanned at this recurring interval

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Are you on mac?

If you're not, then the delay is caused PURELY by the hashing and transfer of the files.

Mac's file-change notification system isn't as straightforward to implement as other platforms.

I'm using Linux (Debian and Ubuntu). Is the MAC the only platform that has the delay problem?

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  • 8 months later...

good morning and thanks for bittorrent sync. it does what all encrypted cloud sync applications should.

i am stumped by the slow folder rescan that i am experiencing on my Macs.

from what i read it seems that even though the Mac OS is slow to detect changes to files, if you set the folder_rescan_interval to a low number, that function should pick up the changes. it still takes an unknown amount of time upwards of 20 minutes for me to get two Macs sitting beside one another in my office to mirror to sync.

is the folder_rescan prevented from "seeing" file changes if the Mac OS has yet to see them? in other words, it wouldn't matter how low you set the folder_rescan_interval because if the Mac OS hasn't seen the change, bittorrent sync can't see it. do i have that correct?

i've now changed disk_low_priority to false to see if maybe that was the issue.

thanks in advance for any info you might have.

have an illustrious day.

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I'm finding that on Debian 7.6 Linux that a sync might start at around 20 minutes after adding the secrets, then it will not take advantage of having the data on the LAN when available -- it sometimes ramps up to high speed via the LAN, but still drops back to remote links with transfers dropping down to very low levels for no good reason at all that I can see.  Eventually the data, in my case about 25GB, would be transferred in about 2 hours.  I've done this with multiple machines, same results, I've even given the local hosts in the preferences to use for the machines still yet to sync up.

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