Importing Existing Dropbox Folder
Dropbox is a cloud storage service which replicates the files stored in the “Dropbox” folder of your computer to all other devices linked to the account.
If you start using a new computer, you can simply install the Dropbox app, sign in, and the files will be downloaded. It is not necessary to copy the files from a previous computer; in fact, doing so is not recommended, because the Dropbox client will be confused about what is in the account and will create duplicates.
One way to migrate Dropbox from one machine to another is to use LAN Sync, where Dropbox will fetch files from other hosts on the same network as much as possible. So if both machines are on, the Dropbox client of the newer machine can fetch everything from a local source.
But if the previous machine is not available, and therefore there is no other host to sync files from, a new Dropbox client must download files entirely from the Internet, and this could take days, weeks or even months.
However, there is a way to migrate an existing Dropbox folder to a new Dropbox which avoids a lot of downloading. The technique relies on the fact that Dropbox automatically performs two optimisations when syncing files:
- If a file being uploaded into the Dropbox account is already in the account, it does not need to be uploaded again. Dropbox adds it to the account instantly (after the process of indexing the file to determine the hash value); and
- If a file being downloaded into the Dropbox folder is already in the Dropbox folder, it copies the file locally, and does not need to download it again.
So while best practice is to let the Dropbox app download the contents of the Dropbox folder without trying to manipulate the files unduly, advanced users who need to reinstate a Dropbox folder which is too large to download in a practical period of time may wish to try the following process:
- On the new computer, download the Dropbox app and sign in. When prompted, choose Selective Sync and turn off all folders.
When Dropbox opens, it will only download whatever is in the root folder and nothing else, and will set up a local copy of the files database. Allow this process to complete.
- Make a folder in the Dropbox folder called, say, ZZZZ.
- Copy the offline version of the Dropbox folder from the old computer to this folder.
As each file is indexed, Dropbox will determine that it is already in the account and will not need to upload it. Thus the entire contents of ZZZZ will be synced relatively quickly.
Allow this process to complete.
- When Dropbox has finished synching, open Preferences → Account and turn on all required folders via Selective Sync.
Dropbox will then “download” the files, but because each file is already stored locally, Dropbox will create a copy of the file using the local version instead of downloading it.
- Once the entire Dropbox folder is synced, the contents of ZZZZ can be removed. Note that removing a large number of files will trigger a lengthy sync process by the Dropbox app.
This technique should allow a large Dropbox account to be set up locally in a matter of days rather than weeks. The Dropbox client still has a lot of processing to perform, but can largely skip downloading files from the Internet.
Note that in all the operations above, it is best to let the Dropbox app process uninterrupted; so don't log out or shutdown while it is in progress. It would also be best to add or remove files from the Dropbox folder as little as possible.