Firstly, a big welcome to all you new BitTorrent Sync users!
Don't know where to begin with Sync? - Check out the Getting Started guide or explore the new Sync Help Center.
The forum has exploded into life since BitTorrent Sync first went "public" on Tuesday 23rd April 2013, so I thought I'd make a supplementary post to compliment the official "BitTorrent Sync FAQ"
I'll keep this updated with simple, concise answers to common questions that keep cropping up, and which aren't, as yet, covered elsewhere.
Having a problem with Sync? Be sure to check out the Unofficial Troubleshooting FAQ as well!
Where can I download the latest version of BitTorrent Sync?
Right here: http://www.bittorren...m/sync/download (Changelog)
Installing on a NAS? See Supported NAS
Other unofficial, user-contributed, packages: Ubuntu/Debian (Servers) | Ubunti/Debian (Desktops) | Gentoo ebuild
Note: If you currently use the auto-update feature of BitTorrent Sync, it may inform you that your "Client version is up to date" despite a newer build being available. This is intentional whilst Sync remains in "beta" - new builds are currently announced here in the forums in the first instance. Not every "beta" build is pushed via auto-update, only those considered significant/more stable. Even then these may not be pushed out to existing users via auto update until several days/weeks after they are first announced on the forums - therefore, before reporting any issues/bugs with Sync, please the pinned topics at the top of this forum to find the latest beta version of Sync, and ensure you're running this first)
Will BitTorrent Sync remain free, or will they start charging for it once it comes out of beta?
BitTorrent Sync will remain free!
"If tomorrow we want to charge you $100 for 10Kb transferred, stop everything related to the app or try to force you not to use BitTorrent Sync, we just physically can't achieve that!
BitTorrent Sync will work tomorrow exactly like it works today, no matter what we will do. And it will work exactly like today even 10 years from now, of course, if we will have computers in future " (Source)
...and in publicising the start of the "beta" phase on 17 July 2013, the team commented: "And don’t worry. BitTorrent Sync is still free, simple to use, and secure. Pretty awesome, huh?"
Is BitTorrent Sync open-source?
BitTorrent Sync isn't open source software, although the developers have previously commented "Never say never - we still consider this option" (Source). There's also a related discussion on whether Sync will be open source here
Some unofficial open-source projects related to Sync that you may be interested in contributing code to include:
- Packaging of BitTorrent Sync for Debianoid operating systems
- Bittorrent Sync indicator for linux desktops
What data is collected/seen by BitTorrent Inc when I use Sync?
According to BitTorrent Inc, "There are 3 points of contact with BitTorrent infrastructure: tracker, relay, and check for update service. If you don't use any of these - we will not get any information about you." For more information on what data is seen by BitTorrent Inc, please see this thread
How secure are "keys"... can they be "guessed"?
In a nut shell, "keys" (formally known as "secrets") are extremely secure, and can't realistically be simply "guessed" by others.
You can find out more in this blog post. Additionally, there are plenty of existing topics discussing this particular topic too: (1 | 2 | 3 | 4 | 5 | 6 | 7). Please review/contribute to these threads before considering opening ANOTHER thread on this subject!
Is there an API available?
Yes! - An API is available with Sync 1.2 and later. Please see the API documentation
There is also a dedicated "API wishlist" thread for contributing your suggestions for API functionality n future updates.
Is there an Android/iPhone Mobile App?
The official android app is available in the Google Play Store and requires Android 2.2 or higher, and is currently only supported on ARM architecture (for x86 architecture support please see this thread).
The official iOS app is available in the iTunes Store and requires iOS 5.0 or higher.
A Windows Phone app is also available from the Windows Store and requires Windows Phone 8 or higher.
An Amazon Kindle app is available in the Amazon App Store.
You can also request mobile-specific features for the various Sync mobile clients in this thread.
What about Blackberry support? See this post
Can I control how frequently syncing occurs?
Syncing happens in real time. In addition, as a fall back, BitTorrent Sync also rescans files/folders every 10 minutes by default. If you're running BitTorrent Sync 1.1.12 (or later), you can now configure this interval via the advanced "folder_rescan_interval" setting (default value is "600" (seconds) = 10 minutes)
Will me devices still sync when switched off?
BitTorrent Sync is not a cloud storage solution like SkyDrive/DropBox/GDrive, etc - it doesn't sync your files to a "cloud", therefore for one device to sync with another, both devices need to be online.
If you require an always-on "cloud" functionality for Sync, there are a number of companies now offering dedicated BitTorrent Sync solutions, some of which you'll find listed here
Can I use BitTorrent Sync to backup from an internal drive to an externally connected USB drive?
No, BitTorrent Sync will not permit you to sync one folder location on your computer to another location on the same computer (i.e. you can't have two shared folders using the same "secret" on the same device)
Can I force Sync to do local network (LAN) syncing only and not sync via the Internet?
Yes - simply disable the Relay, Tracker, and DHT options (these are per-folder settings). Sync will then no longer connect to any remote devices (outside your local network).
What do the device icons mean?
Direct Connection - BitTorrent Sync is able to establish a direct connection to this device
Indirect (Relayed) Connection - BitTorrent Sync isn't able to establish a direct connection to this device, and therefore has connected via a intermediate relay server. It is preferable to have direct connections wherever possible, as this will generally provide faster transfer speeds over that of a relayed connection.
What are .SyncID, .SyncIgnore, .SyncPart, .SyncTemp .SyncOld and .!Sync files and the .SyncArchive folder?
When you add a new folder to BitTorrent Sync a number of hidden files/folder are automatically created in the folder. The purpose of each are as follows:
.SyncID (pre 1.4) / .sync/ID (1.4+) = A file containing the unique, internal "ID" of the folder. This file should not be manually modified, or deleted. If you do, the folder will no longer be recognized in BitTorrent Sync.
.SyncIgnore (pre 1.4) / .sync/IgnoreList (1.4+) = A user editable file allowing you to "exclude" certain files/sub folders for being sync'd
.sync/StreamsList (1.4+) = A user editable file allowing you to "white list" alternate streams, xattrs and resource forks (mainly for OSX users)
.SyncArchive (pre 1.4) / .sync/Archive (1.4+) = BitTorrent Sync, by default, won't actually delete any of your files/folders. If a corresponding file/folder is deleted on another device, it will simply be "moved" into the .SyncArchive folder on all other devices, rather than being permanently deleted. (In Sync pre v1.1.40, this folder was named .SyncTrash and was later renamed to .SyncArchive as this folder now stores both local files deleted on remote devices, as well as "versioned" files. From Sync 1.4 onwards, this folder has again been renamed to .sync/Archive)
.!Sync files = Temporary files created by BitTorrent Sync when receiving incoming data transfers. Once a file is fully received, it is then renamed to have its .!Sync extension removed i.e. "file.mp3" will become "file.mp3.!Sync" on receiving devices until all data for the file is fully received, at which point it will be renamed back to "file.mp3".
.SyncPart / .SyncTemp = Please see this post
.SyncOld = Usually contains a backup of a file when that file gets transferred to your device partially from another location. After the transfer is successful, the .syncold file gets moved to .SyncArchive folder (if allowed in settings).
Is there a limit on the number/size of files I can sync?
There are no limits imposed on the number, or size, of files you can sync with BitTorrent Sync, however there are two factors to take into account:
- How much free disc space you have on the devices you're syncing - if you do not have enough free disc space for the files you wish to sync, they will not sync
- How much free memory your devices have. In 1.1.x builds, memory usage increases by around 300-400 bytes per file being monitored by BitTorrent Sync. Therefore, if you're monitoring/syncing 1 million files, you will need around 300-400 MB of free memory.
Is there a limit on the number of devices I can connect/share with?
As the current free offering of Sync is designed primarily for home/personal use, there is a 50 peer limit per secret. The ability to change/raise this limit will likely be an enterprise/business feature in the future.
When a file changes, does BitTorrent Sync transfer the entire file again, or just the part that's changed?
Files smaller than 4MB are transferred again in their entirety when changes are detected.
Larger files, however, are split into 4MB "chunks" of data, if one chunk changes, but the others don't, only the chunk that's changed will be transferred (instead of the whole file again). (Source)
How long are files kept in .SyncTrash/.SyncArchive for?
From v1.1.30 onwards, deleted files are kept in .SyncArchive (or .SyncTrash pre v1.1.40, or .sync/Archive from 1.4 onwards) for a default period of 30 days, after which they will be automatically removed. You can change this default period by adjusting the advanced "sync_trash_ttl" setting.
What's the difference between "Secrets" and "Keys"?
Nothing! They are the same! In Sync 1.3 (and earlier) the term "Secret" was used. In Sync 1.4 and later, the term "Key" is used instead - they refer to the same thing.
Is "SyncApp" the same as "BitTorrent Sync"?
Yes, "SyncApp" was the former name of "BitTorrent Sync", so if you see lingering references to "SyncApp" in the forums or elsewhere, don't be concerned! - they are one and the same!
How do I use "*" and "?" wildcards in .SyncIgnore files?
"?" is a substitute for a single character instance,
"*" is a substitute for multiple character instances.
- *.dat would exclude from syncing all .dat files types regardless of name i.e. myfile.dat, anotherfile.dat, ete
- abc???.dat would exclude from syncing files named "abc123.dat", "abcdef.dat", etc... but wouldn't exclude files named "abc1.dat" or "abcdefg.dat", etc
- *.mp? would exclude from syncing file types such as .mp3, .mp4, .mpa, etc, but wouldn't exclude file types such as .mpeg
- /*.avi would exclude from syncing .avi file types contained in the root folder only (any .avi files in sub folders will still sync)
How can I improve sync/transfer speed?
A number of factors can affect how quickly your files transfer between devices. One of the most significant is whether your other devices are connected "directly" (i.e. appear on the same LAN), or "indirectly" (relayed). to determine this, please see "What do the device icons mean?" above.
Generally speaking, "direct" connections are preferable as they are significantly faster than relayed connections. Therefore, the first step to improving sync speed would be to try and ensure that direct connections are established between your devices. If they all reside on the same physical local LAN, this shouldn't be a problem. However, if they are "remote", you could consider establishing an VPN in order to make your remote devices appear as though they're all on the same local LAN.
Once your devices all appear on the same LAN, follow the steps outlined above for "Can I force Sync to do local network (LAN) syncing only and not sync via the Internet?" to restrict syncing to your local LAN.
Next, if possible, assign static IPs to your devices, and then use the "pre-defined hosts" settings (again, these are per folder) to list your devices. At the same time, untick the "Search LAN" option. By doing this, Sync will then know exactly where to connect without having to spend time searching for other devices.
Make sure you've not set any upload/download rate limits in Sync, and set the advanced "rate_limit_local_peers" setting is set to "false"
Another advanced setting that can be set to "false" to potentially further improve transfer speed is the "lan_encrypt_data" setting.
If you have a more powerful device, you could also consider setting "disk_low_priority" to "false", and increasing the size of "recv_buf_size" and "send_buf_size" to get a further speed advantage.
One final thing that can improve overall performance of Sync is how fragmented your hard discs are. The less fragmented, the better nc indexing speed will be - so if you've not de-fragmented your drives for a while, it's worth doing!
How to make BitTorrent Sync "Portable"
Running Sync directly from a USB Stick/Memory Card was officially supported up until version 1.2.24. The Sync team have since removed this option in more recent builds whilst they focus on "higher priority" development tasks. "Portable Mode" may return in the future.
In the meantime, there is an unofficial workaround to run the latest builds of 1.3.x in "Portable Mode" directly from your USB Stick/Memory Card, however, do bear in mind that "Portable Mode" is no longer officially supported, and won't work at all with 1.4.x builds.
How to make BitTorrent Sync run as a service
Please see Start Sync as a service on Windows
Is there a Command Line Interface (CLI) for BitTorrent Sync on Windows?
Not at this time! The CLI is only available for Linux builds
Is there a MIPS build?
There are no MIPS builds of BitTorrent Sync at the present time, however, according to the developers, "We plan to add MIPS support", although there is no timescale at present.
How do you define multiple shared folders in the config file?
Please see this thread
How do you secure the WebUI with a password?
By default, the web-based User Interface for BitTorrent Sync isn't password protected. To protect your WebUI (recommended) please see this thread
...Please do bear in mind that BitTorrent Sync is currently just a "beta", and therefore it may not currently have all the features/functionality/behavior that you'd ideally like to see! If you experience an issue/bug there are instructions on how to report it here. There is also a dedicated and very active "Feature Requests" forum where you can contribute ideas & suggestions as to what you think would make BitTorrent Sync even better! The developers do read all these feature requests, and are taking note as to the popularity of each suggestion... so give them time, and I'm sure BitTorrent Sync will get ever better!
Edited by GreatMarko, 10 October 2014 - 10:11 PM.