Cloud Sync

With Cloud Sync, you can seamlessly sync and share files among your Synology NAS and multiple public cloud services, including:

Create New Connections

To sync files among your Synology NAS and public cloud services, you need to create connections on Cloud Sync to link to the service provider by using your user credentials.

To create a new connection:

  1. On the Cloud Sync user interface, click on the Create icon at the bottom-left corner to start the wizard.
  2. Choose one of the following public cloud services to sync files with and click Next.
  3. Once authentication has been successful, fill in the following fields and then click Next.
  4. To further adjust your sync settings, click Advanced settings.
  5. Click Apply to save your settings.

Note:

  1. Each user credential can only be used for creating one connection. You can create multiple connections all with different user credentials, but not duplicate connections with the same user credential.
  2. If you selected Upload local changes only or Bidirectional for Sync direction, Cloud Sync will synchronize all subfolders and files within the selected folder.
  3. Due to Baidu's limitations, you are only allowed to sync files to the My Application's Data > Cloud Sync folder in your Baidu Cloud storage.
  4. File or folder names that end with a period (.) or a space will be renamed as "file name._DiskStation_modified date_TailCharacterConflict".
  5. When using Cubby via WebDAV, if a folder containing files is deleted, Cubby server will recreate it after syncing. (For example, if you delete 'folder /A', Cubby will download the folder and its contents as 'folder /a'.)
  6. As a general rule, files will not be synced by Cloud Sync under the following circumstances:
    • The folder or file path contains NFD characters or the following characters:
      : \ /
    • The file name starts with any of the following:
      ._ ~.SYNOPPSDB
    • The file/folder name is any of the following:
      .ds_store, desktop.ini, @eadir, thumbs.db, .SynologyWorkingDirectory, #recycle, Icon\r, $Recycle.Bin, @sharebin, @SynologyCloudSync, cloudsync_encrypt.info, @ActiveBackup, ActiveBackupData, #snapshot, ActiveBackupForOffice365, ActiveBackupForGSuite
    • The folder or file in the @tmp folder of the root folder.
    • The folder or file path is longer than 2,048 characters.
    • The file name is longer than 255 characters.
    • The folder or file is located in a mount point or an external storage device.
    • The folder or file under a folder is being mounted using a bind mount.
  7. In special cases, files will not be synced by Cloud Sync under the following circumstances:
    • For Synology C2 Object Storage if:
      • The folder or file path is longer than 1,024 characters.
      • The size of a single file exceeds 5 TB.
      • The folder or file path contains the following characters:
        " < > | { ^ } % ` ] [ ~ #
      • The folder or file name is . or ..
    • For Hybrid Share if:
      • The size of a single file exceeds 64 GB.
    • For Alibaba Cloud OSS if:
      • The folder or file path is longer than 1,023 characters.
      • The size of a single file exceeds 48.8 TB.
      • The folder or file name is . or ..
    • For Amazon S3 if:
      • The folder or file path is longer than 1,024 characters.
      • The size of a single file exceeds 5 TB.
      • The folder or file path contains the following characters:
        " < > | { ^ } % ` ] [ ~ #
      • The folder or file name is . or ..
    • For hicloud S3 if:
      • The folder or file path is longer than 255 characters.
      • The size of a single file exceeds 1 TB.
      • The folder or file path contains the following characters:
        " < > | { ^ } % ` ] [ ~ #
      • The folder or file name is . or ..
    • For Backblaze B2 if:
      • The folder or file name is .bzEmpty.
      • The folder or file name is longer than 250 characters.
      • The folder or file path is longer than 1,024 characters.
    • For Baidu Cloud if:
      • The file name starts with a period (.).
      • The file/folder name is, or contains any of the following:
        .baohe .cache
      • The folder or file name contains the following characters:
        * ? \ " < > |
      • The storage space has reached the 100 GB limit.
    • For Box if:
      • The size of a single file exceeds your account limit.
      • The type of the file is bookmark.
    • For Dropbox and Dropbox Team Space if:
      • The file name starts with any of the following:
        .dropbox .cache
      • The file/folder name is, or contains .dropbox.
      • The file has been uploaded for more than 48 hours.
      • The size of a single file exceeds 350 GB.
      • The number of folders exceeds 5,000. (Learn more)
    • For Google Cloud Storage if:
      • The size of a single file exceeds 5 TB.
      • The folder or file path contains the following characters:
        * ? # [ ]
      • The file/folder name is blank.
      • The folder or file path is longer than 1,024 characters.
    • For Google Drive and Google Shared Drive if:
      • The size of a single file exceeds 5 TB.
    • For JD Cloud OSS if:
      • The folder or file path is longer than 1,021 characters.
      • The size of a single file exceeds 19 TB.
      • The folder or file path contains the following characters:
        # % +
      • The folder or file name is . or ..
    • For MegaFon MegaDisk if:
      • The folder or file path contains the following characters:
        * ? " < > |
    • For Microsoft Azure if:
      • The size of a single file exceeds 4.75 TB.
      • The folder or file name is .synoemptyblob.
      • The full file path is longer than 1,024 characters.
      • The file name is longer than 255 characters.
    • For Microsoft OneDrive if:
      • The type of the file is a note document.
      • The size of a single file exceeds 250 GB. (Default: 100 GB)
      • The file name begins with a space.
      • The folder is shared by others.
      • The folder or file name contains the following characters:
        : * ? " < > | \ /
    • For Microsoft OneDrive for Business if:
      • The type of the file is a note document.
      • The size of a single file exceeds 250 GB. (Default: 100 GB)
      • The file name begins with a space.
      • The file name is longer than 128 characters.
      • The full file path is longer than 308 characters.
      • The folder or file name contains the following characters:
        \ / : * ? "< >|
      • The folder or file name ends with the following:
        .
      • The folder or file name is one of the following:
        forms ~
      • The folder or file name contains the following:
        _vti_
    • For Microsoft SharePoint Online if:
      • The size of a single file exceeds 15 GB.
      • The file name is longer than 128 characters.
      • The full file path is longer than 308 characters.
      • The folder or file name contains the following characters:
        \ / : * ? "< >|
      • The folder or file name ends with the following:
        .
      • The folder or file name is one of the following:
        forms ~
      • The folder or file name contains the following:
        _vti_
    • For OpenStack Swift compatible cloud services if:
      • RackSpace
      • RackSpace UK
      • The folder or file path is longer than 1,024 characters.
      • The folder or file path contains the following characters:
        ?
    • For Tencent Cloud COS if:
      • The folder or file path is longer than 797 characters.
      • The size of a single file exceeds 48.8 TB.
      • The folder or file path contains the following character:
        ? ~
      • The folder or file name is . or ..
  8. Cloud Sync on DSM cannot instantly sync the file changes made on Docker DSM or other containers; likewise, Cloud Sync on Docker DSM or other containers cannot instantly sync the file changes made on DSM.
  9. When setting the file names that you don't want to sync, file names will be considered the same if one file name is capitalized and the other has the same name but in lower case (e.g., A.txt and a.txt) on Windows; however, they will be considered different file names on Linux and Mac systems.
  10. Cloud Sync and the following services follow the OAuth authentication standard: Amazon Drive, Baidu Cloud, Box, Dropbox, Google Cloud Storage, Google Drive, MegaFon MegaDisk, and Microsoft OneDrive. OAuth 2 requires another server (which is hosted by Synology and located in Taiwan) to complete the authentication. Your Synology NAS will not remember or keep your account password. Your user credentials will only be used for the purposes of file transfer and syncing. Cloud Sync will not access or disclose any other personal account information such as contacts.
  11. Cloud Sync does not impose any single file size limit. You can sync as big a file as the public cloud services allow.
  12. Support for Megadisk allows you to use Synology NAS as backup storage for Megadisk. Please note that, depending on your location and various conditions, the upload speed from Synology NAS to Megadisk might be limited, so we do not encourage using Megadisk as backup storage for your Synology NAS.
  13. Google Cloud Storage Nearline Storage Class is designed for data that is not frequently modified, so when you edit or delete a file, early deletion charges may apply.
  14. When uploading to Google Cloud Storage, Cloud Sync will not enable object versioning.
  15. If a single file exceeds the allocated segment size, OpenStack Swift will upload it using Dynamic Large Objects.
  16. OpenStack Swift Container name cannot exceed 255 characters and cannot include '/'.
  17. Amazon Drive does not support login with Amazon in China and Japan marketplaces. Please see the Platform Limitations provided by Amazon Drive.
  18. Data encryption:
    • To enable data encryption, you must have read-write permission to the remote root folder.
    • Once you have enabled encryption, you cannot disable it or change its password.
    • Local files on your NAS will remain unencrypted.
    • Each public cloud account has only one encryption key.
    • Once encryption has been enabled, Cloud Sync will create a folder named @SynologyCloudSync on the public cloud. Please do not change the files within that folder.
    • An Export button will appear in Settings upon first use. Click the button to export the key, and keep it in a safe place.
  19. Amazon Infrequent Access Storage is designed for data that is not frequently modified, so when you edit or delete a file, early deletion charges may apply.
  20. When configuring a Google Drive sync task to be Download remote changes only, you can also enable Convert Google online documents to Microsoft Office or jpeg formats to keep an offline copy of your Google Docs. Note that the changes made to the offline office documents will not be converted and updated back to Google Docs.
  21. With Enable advanced consistency check ticked, Cloud Sync compares the hash (in addition to file size and last modified time) of each file between the public cloud and the NAS to enhance the integrity check of the sync results. This will require more time and system resources, and depends on the public clouds' support for advanced attributes. Please refer to the bottom of the page for more information.
  22. Bucket name must comply with the following rules:
      For cloud services compatible with Amazon S3 (Amazon S3, hicloud S3, and SFR Stockage) and Alibaba Cloud OSS:
    • The name length must be between 3 and 63 characters.
    • The name must start with a lowercase letter or number.
    • The name can only contain lowercase letters, numbers, or the following:
      . -
      For Backblaze B2:
    • The name length must be between 6 and 50 characters.
    • The name cannot start with b2-.
      For Tencent Cloud COS:
    • The name length cannot exceed 40 characters.
    • The name can only contain lowercase letters or numbers.
      For JD Cloud OSS:
    • The name length must be between 3 and 63 characters.
    • The name must start and end with a lowercase letter or number.
    • The name can only contain lowercase letters, numbers, or the character -.
  23. Cloud Sync supports Amazon Infrequent Access (IA), Reduced Redundancy Storage (RRS), and S3 Standard for file uploads and downloads, but does not support Glacier for file uploads and downloads.
  24. Cloud providers such as Aliyun, Tencent, or JD Cloud do not support Glacier for file uploads and downloads.
  25. As a general rule, folders in remote destinations will not be listed by Cloud Sync under the following circumstances:
    • The folder contains the following characters:
      / \
    • The folder does not have a folder name.
    • The folder name ends with a space.
  26. Cloud Sync only supports Tencent Cloud COS V5.
  27. Drive SDK API must be enabled on Google Admin console to allow data synchronization between Synology NAS and Google G Suite My Drive.
  28. Cloud Sync does not support syncing files in Google Drive Shared with me, Computers, and Shortcuts.
  29. To sync the team folders of upgraded Dropbox Business accounts (Team Space), select Dropbox Team Space when creating the connection. To sync other folders or member folders in Dropbox, select Dropbox.

Manage Connections

Once a connection has been successfully created, you can view and modify the connection information.

To manage connections:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Under the Overview tab, click Manage to do any of the following:

To manage schedule settings:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Go to Schedule > Schedule settings to configure the following:

Note:

Backup tasks will be terminated when entering the suspend mode.

To edit a connection settings:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Go to Settings > General settings to configure the following:
  3. Click Apply to save your settings.

Note:

Polling period refers to how often Cloud Sync polls for changes on the public cloud and syncs the changes to the local folder. For example, if you set your polling period as 1 hour, Cloud Sync will connect to the public cloud and search for file changes every hour. The maximum polling period is one day (86,400 seconds).

To manage Traffic Control:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Go to Settings > Traffic Control to configure the following:
  3. If the value of this field is 0, it means that there is no limit to the rate of file transfer.
  4. Click Apply to save your settings.

Note:

The traffic control setting applies to the entire public cloud connection, and is shared by all files being transferred concurrently.

To manage Synology C2 Object Storage advanced settings:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Go to Settings and under Advanced settings, do the following:
  3. Click Apply to save your settings.

To manage S3 advanced settings:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Go to Settings and under Amazon S3 advanced settings, do any of the following:
  3. Click Apply to save your settings.

To manage Alibaba Cloud OSS advanced settings:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Go to Settings and under Advanced settings, do any of the following:
  3. Click Apply to save your settings.

To manage OpenStack Swift advanced settings:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Go to Settings and under OpenStack Swift advanced settings, do the following:
  3. Click Apply to save your settings.

To manage Backblaze B2 advanced settings:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Go to Settings and under Backblaze B2, do the following:
  3. Click Apply to save your settings.

To manage Tencent Cloud COS advanced settings:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Go to Settings and under Advanced settings, do the following:
  3. Click Apply to save your settings.

To manage JD Cloud OSS advanced settings:

  1. Select the connection you want to edit from the connection list on the left panel.
  2. Go to Settings and under Advanced settings, do the following:
  3. Click Apply to save your settings.

Manage Sync Task List

After successfully connecting with the public cloud services, you can view, add, delete, or edit your sync tasks.

To add a sync task:

  1. Select a connection from the connection list on the left.
  2. Go to the Task list tab.
  3. Click Create and follow the wizard to create a new sync task.

Note:

When selecting a folder to sync, it cannot be in the same directory as one already synced in the same connection.

To remove a sync task:

  1. Select a connection from the connection list on the left.
  2. Go to the Task list tab.
  3. Select a sync task and click Unlink.

Note:

After unlinking a task, a full re-sync might be required if you wish to link again. When you set up a new connection, Cloud Sync will automatically compare existing files and only upload/ download the changes that have been made.

To manage Cloud Sync selective sync settings:

Selective Sync is a feature of the Cloud Sync application that allows you to filter the files or select the folders you want to sync to the public cloud service. Selective Sync allows you to ensure you have only the files you need on the public cloud service or vice versa.

  1. Select a public cloud service from the connection list on the left.
  2. Go to the Task List tab.
  3. Select a sync task and click Edit.
  4. In the Folder tab, select the folders you want to sync and click OK to save your settings.
  5. In the File Filter tab, you can configure the following options:
  6. Click OK to save your settings.

To modify sync direction:

  1. Select a public cloud service from the connection list on the left.
  2. Go to the Task list tab.
  3. Select a sync task and click Task settings.
  4. In the Settings tab, configure any of the following:

Note:

Cloud Sync will sync all newly added files and folders by default.

Manage Cloud Sync from DSM System Tray

After you have installed and launched Cloud Sync, a package icon will appear at the top-right corner of your DSM system tray. You can easily and efficiently manage Cloud Sync and perform the following actions from the system tray:

Settings

Administrators can click the Settings icon on the bottom-right and under Administrator Controls, specify Cloud Sync database location, maximum concurrent uploads/downloads, maximum number of logs kept, and switch to administrator mode.

To specify the database location:

  1. Select a volume in the Database Location Settings dropdown menu.
  2. Click OK to save your settings.

To specify the concurrent uploads/downloads:

  1. Select a number in the Concurrent uploads/downloads dropdown menu.
  2. Click OK to save your settings.

To specify maximum records in history log:

  1. In the Maximum records field, input a number between 5 and 100,000.
  2. Click OK to save your settings.

To enable administrator mode

  1. Select Enabled in the Admin mode drop-down menu to manage the connections of all Cloud Sync users. You can specify the order of these connections by user account or cloud type in the overview.
  2. Click OK to save your settings.

For Advanced Users

To ensure your files and folders sync correctly, please note the following information.

Supported file attributes of the public clouds

Platform File hash Last modified time
Synology C2 Object Storage O (md5) X
Dropbox X O
Dropbox Team Space X O
Google Drive O (md5) O
Baidu O (md5) X
Box O (sha1) O
Amazon S3 O (md5) X
WebDAV X X
Yandex X X
Amazon Drive O (md5) X
MegaFon O (md5) O
OpenStack Swift O (md5) O (1)
Google Cloud Storage O (md5) O (1)
Google Shared Drive O O
Microsoft OneDrive O (sha1) O
Microsoft OneDrive for Business X X
Microsoft Azure O (md5) O (1)
Microsoft SharePoint O X
Backblaze B2 O (sha1) O (1)
Alibaba Cloud OSS O (md5) X
Tencent Cloud COS O (md5) X
JD Cloud OSS O (md5) X

1: These public cloud providers do not allow the last modified time attribute to be updated, but provides a custom file attribute field for third-party apps like Cloud Sync. Cloud Sync will save the last modified time in the customized file attribute field. This means Cloud Sync's last modified time will not be updated on the public cloud web interface and other sync clients.

Note:

  1. Due to the file system limitation, after you modified the data on your Synology NAS, Last modified time of the directory on your cloud service and Synology NAS may be different.
  2. Only Box, Dropbox, Google Drive, MegaFon, and OneDrive allow third parties to update the last modified time, meaning that the last modified time of other public cloud services is always the time when files are uploaded.
  3. Hash values are not available for files uploaded to Amazon S3, Alibaba Cloud OSS, Tencent Cloud COS, or JD Cloud OSS via multi-part upload.
  4. Hash values are not available for files uploaded to OpenStack Swift via Dynamic Large Object upload.
  5. Hash values are not available for files uploaded to Backblaze B2 via b2_upload_part upload.
  6. Cloud Sync uses Google Cloud Storage's md5 hash. The crc32 hash of composite object is not adopted.
  7. Increasing the number of concurrent uploads/downloads can improve synchronization performance when the network and resource conditions allow.

Metadata that will not be synced to your public cloud services:

Default action for conflicted copy:

If a file or directory is modified on both your local Synology NAS and remote public cloud account at the same time, Cloud Sync will try to keep the local changes as much as possible, and the remote changes will be saved as one revision if the cloud service supports versioning.

The following cloud services prevent your Synology NAS from entering System Hibernation:

For more details about services that may affect system hibernation, please see this FAQ

Why does Cloud Sync continuously download the same file from Baidu Cloud?

After files have been uploaded to Baidu Cloud, Cloud Sync will compare the file hash on both sides to confirm consistency. We found that in many cases, Baidu will respond with an incorrect hash value, causing Cloud Sync to detect that the files on the public cloud differ from those on your Synology NAS. Because of this, Cloud Sync will try to align the versions, and commence sync again, causing the repeated download of the same file.

Why is Cloud Sync slower than other cloud services' PC applications?

Due to the below limitations, Cloud Sync might take longer to sync files with public cloud services than the official PC applications such as Dropbox and Baidu.

Given the above limitations, the syncing performance of Cloud Sync shall continue to be enhanced, while also maintaining the safety and security of your Synology NAS.