Cloudsync is slow, Tips and Tricks

Good evening Team SpaceRex Forum Family!

I recently decided to go with Dropbox for my offsite cloud backup. I have a fiber connection (900 Up and Down) and in less than 4 nights 2.5TB uploaded LIKE A BEAST! The last 500GB was taking WEEKS!

After a bit of research and testing, I learned that some types of files cause Cloudsync to be EXTREMELY SLOW. In fact I added 20GB of video files and that uploaded faster than the current upload taking place in Cloudsync and I added it inside of the folders being synced via Cloudsync.

Once I moved these files and unchecked the folders in cloud sync settings, the rest of the 500GB uploaded in less than a day!

So far, the following file type caused Cloudsync to just come to a super stall of weeks:

MBOX Files (OSX Mail Mailbox Exports), This was just 9GB

OSX Install Files (The Installers for OSX Sierra, Maverick, ect)

iPhoto Libraries (Sad but true, trying it again)

Older App Files (Apps like Pages 09’ and other older Apps)

If anyone else discovered anything please let me know!

1 Like

@SynologyRichie so this is actually something that you really can speed up!

Why Cloud Sync Can Be Slow:

So Cloud Sync actually has the ability to be faster (at least for very first upload) then any other backup method due to it actually being multi threatened. But it has two real downsides in terms of performance:

  1. Every single file has to have its own upload job. This means that things like sparse bundles or mail boxes which have millions of small files can take a long time to upload and track
  2. It is not file system operation aware (and to operate with everything it really cannot be). It does not track moves or renames of files or folders. Instead it only tracks what is there. So if you were to rename a folder, which had 10 TB of files and sub folders, cloud sync would see that as the old folder being deleted, and a new folder being created, which would force it to upload all 10 TB of files all over again.

How to make Cloud Sync Fast:

But one thing that it does have going for it is multithreading for uploads (file based). This is something that no other Synology Apps (I really wish Drive Share Sync would have a setting for this) has. This will upload multiple files at the exact same time. Setting this too high can really take up disk IO, so you need to play with it on your system. Set Concurrent uploads/downloads to something like 10 to start.

The other thing you can do is set the polling period to something like 30 min for a massive file server if you are just looking for a backup.

Overall Cloud Sync is the fastest way to transfer files over a high latency connection because of the ability to multi thread file uploads. Note: This does not help a ton if you just have 1 200gig file you want to transfer as the multi threading is file by file


Spacerex is a gem that must be protected! =)

Yes I had these settings on, and I agree once I cleared those files it went hyper fast. The renaming thing is really fascinating because imagine the load on the network just because you changed a file that’s crazy :cry:

Update - I noticed that it’s super fast to actually upload those sparse type files (MBOX, iPhoto Library ECT.) to the cloud service directly and then let Synology download the new files instead of placing them onto the Synology to upload to the cloud service.

Those MBOX files? DONE! =)

So that is really wild! I am wondering if you have a latency issue or something like that because there should not be that large of a difference between uploading and downloading from a cloud sync perspective when it comes to thousands of files. The only thing that I think otherwise could be it are metadata lookups while the files are uploading, but that should not be too slow!

Good to know!