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Global file system mirror

File system mirroring refers to creating a complete read-only image for a file system with the same content but with a separate file system name and access credentials.

JuiceFS's file system mirror is not restricted to the same region and can be freely deployed between all JuiceFS-supported cloud providers and regions. For example, you can create a mirror of Alibaba Cloud China for the AWS US file system.

How it works

The file system mirror works as shown below:

After the mirror file system is created, JuiceFS automatically copies the metadata from the original region to the mirrored region with a second-order delay.

After the mirror file system is mounted, the client pulls data from the object storage of the original file system and writes it to the object storage of the mirror file system.

To improve the mirror synchronization speed, you can mount multiple clients concurrently for reading and writing. Because large files are split into 4MB blocks, the number of concurrent calls can be very high, effectively reducing the latency of data synchronization. Even if you synchronize across continents, the mirror delay can be controlled to within 30s.

After the mirror file system is mounted, the data will be read first from the local object storage. If it fails (when the synchronization has not been completed), it will try to read from the object storage of the original file system, as shown in the following figure:

When the image file is mounted for the first time, it will automatically start synchronizing the historical data. Users can also use the juicefs heal command to manually synchronize data.

How to enable

If you want to enable global file system mirroring, please contact JuiceFS's technical support to complete the creation and deployment.

Billing Notes

When using file system mirroring, a file system can create multiple read-only mirrors in multiple different regions, each of which is billed separately.