The express synchronization feature of Cloud Storage Gateway (CSG) allows you to efficiently synchronize changes in an Object Storage Service (OSS) bucket to all local clients that are connected to the bucket by using a file gateway.
Prerequisites
A file gateway is created, and a cache disk is attached to it. For more information, see Create a file gateway and Attach a cache disk.
An OSS bucket is created. For more information, see Create buckets.
A Network File System (NFS) or Server Message Block (SMB) share is created and configured for the file gateway. For more information, see Manage shares.
Simple Message Queue (SMQ) is activated. For more information, see Activate SMQ and authorize RAM users to access SMQ.
Background information
When you configure the express synchronization feature, you can add one or more shares that are connected to the same OSS bucket to an express synchronization group. All data changes in the bucket are simultaneously synchronized to the CSG agents that are mapped to the shares in the express synchronization group. You do not need to separately synchronize data changes from the bucket. This improves the efficiency and accuracy of data synchronization.
The express synchronization feature relies on Simple Message Queue (formerly MNS) and incurs SMQ fees. For more information, see Billing.
Create a synchronization group
If you delete an object from a versioning-enabled bucket without specifying a version ID, the event notification rule for the DeleteObject or DeleteObjects event is not triggered. This is because a request to delete an object from a versioning-enabled bucket without a version ID specified does not actually delete any object version. Instead, the current version of the object is made a previous version and a delete marker is added as the current version of the object. As a result, CSG detects no deletion operation on the object.
To enable express synchronization, you must create a synchronization group and add shares to the group.
Log on to the CSG console.
In the upper-left corner of the console, select the region where the file gateway resides.
In the left-side navigation pane, click Express Sync.
In the upper-right corner of the Sync Groups page, click Create.
In the Basic Information step of the Create Sync Group wizard, configure the parameters described in the following table and click Next.
Parameter
Description
Sync Group Name
Enter the name of the synchronization group.
NoteThe synchronization group name must be 1 to 128 characters in length, and can contain letters, digits, periods (.), underscores (_), and hyphens (-). It must start with a letter.
OSS Region
Specify the region where the OSS bucket resides.
Bucket Name
Select the name of the OSS bucket. You can select only one OSS bucket for an express synchronization group. All data changes in the bucket are synchronized to the CSG agents that are mapped to the shares in the group.
NoteIf no share is connected to the OSS bucket, no OSS bucket is available in the drop-down list. In this case, you must create a share in the file gateway to map your CSG agent to the OSS bucket. For more information, see Manage shares.
Bucket Subdirectory
Select a specific subdirectory of the bucket from which you want to synchronize data.
In the Sync Group Settings step of the Create Sync Group wizard, select the intended shares from the Available Shares section and click the > icon. The shares are displayed in the Selected Shares section. Click Next.
To remove a share from the selected shares, select the share in the Selected Shares section and click the < icon.
NoteAfter you add an NFS share to a synchronization group, you can specify the noac parameter when you mount the share to a local directory on the CSG agent. This allows you to view the synchronization result at the earliest opportunity. For more information, see Access an NFS share.
In the Confirmation step of the Create Sync Group wizard, confirm information about the synchronization group. If nothing goes wrong, click OK.
Manage a synchronization group
After you create a synchronization group, all data changes in the OSS bucket are automatically synchronized to the CSG agents that are mapped to the shares in the synchronization group. You can perform the following operations to manage a synchronization group:
View the details of a synchronization group
On the Sync Groups page, click the synchronization group name in the Sync Group Name column or click Details in the Actions column.
In the Sync Group Details dialog box, you can view the details of the synchronization group. You can also click the
icon to view the details in a list, or click the 
icon to view the details on a map. The Sync Group Details dialog box shows the basic information of the synchronization group and the shares in the group. You can also view the following information from the list. Item
Description
Message Topic Name
The name of the topic that is used by the synchronization group.
Shared Status
The status of the share in the synchronization group. The share can be in one of the following states:
Full Data Sync Awaiting: indicates that the share is waiting for the initial full synchronization.
Full Data Sync in Progress: indicates that the share is being used for the full synchronization.
Sync Normal: indicates that the share is being used to synchronize data as expected.
Express Sync Disabled: indicates that the express synchronization feature is disabled for the share.
Message Queue Inaccessible: indicates that the queue that corresponds to the share cannot be accessed.
Message Topic Inaccessible: indicates that the topic that corresponds to the share cannot be accessed.
Message Queue and Topic Inaccessible: indicates that the queue and topic that correspond to the share cannot be accessed.
Message Queue Name
The name of the queue that is used by the synchronization group.
Add a share to or remove a share from a synchronization group
Find the synchronization group and click Settings in the Actions column. In the Set Sync Group dialog box, add a share to or remove a share from the synchronization group. To add or remove a share, follow the instructions in Step 6 in the Create a synchronization group section.
Delete a synchronization group
To delete a synchronization group, find the synchronization group on the Sync Groups page and click Delete in the Actions column. In the message that appears, click OK.