2011-01-10

Dropbox LAN Sync

One of the programs I love to use is Dropbox ... provides great sync of files across multiple devices, and into the cloud. Dropbox recently added support for Selective Sync, meaning I can throw a bunch of files into the cloud and only sync down the stuff I want onto each device ... so for example Dad can have all his hockey pics, without having to carry Mom's teaching files around on his laptop ... and so on. One of the features in Dropbox is called "LAN sync". The way this works is that if you've got multiple PCs installed, Dropbox will find out that you're on a LAN and will sync directly between PCs, without the intermediary hop to the cloud. There are pros and cons to this. The key pro is that sync is very fast on your local LAN ... if I modify a file on one laptop it shows up on the other laptop in seconds. Makes for a great poor-man's DR solution in that if my laptop dies, I have all my files synched on a second machine within seconds. Nice. But the caveat of LAN sync is that to achieve this, every machine running Dropbox sends a broadcast across your LAN every few seconds. For example, if I look at a packet capture for my LAN I see "[source IP] 255.255.2555.255 DB-LSP-Dropbox LAN Sync Discovery Protocol" every few seconds. Some of you won't care, but this adds a fair bit of traffic on your network and will degrade performance, especially if you have multiple computers set to use LAN sync. To disable, just right-click Dropbox in your system tray, choose the General tab, and de-select "Enable LAN Sync". It would be nice if Dropbox allowed some tuning of this feature, or even provided a mechanism to manually 'tell' Dropbox where the other Dropbox-enabled machines were on a given network. On a related note, I'd be interested in hearing whether any of you are using Dropbox for PST synch. I've heard claims from some Dropbox forum members that this works well, but I'm skeptical. Haven't tried yet, and suspect PSTs would become corrupt over time. Has anyone tried?