freezer/FAQ.rst

FAQ

1. What is freezer? Is a tool to automate data backup and restore process using OpenStack Swift.
2. Does freezer support incremental backup? Yes. Incremental backup are done using GNU tar incremental features
3. Does freezer check the file contents to establish if a file was modified or not? No. Freezer check for changes at mtime and ctime in every file inode to evaluate if a file changed or not.
4. Why GNU tar rather then rsync? Both approaches are good. Rsync check the file content, while tar check the file inode. In our environment, we need to backup directories with size > 300GB and tens of thousands of files. Rsync approach is effective but slow. Tar is fast as it needs to check only the file inodes, rather then the full file content.
5. Does feezer support encrypted backup? Yes. Freezer encrypt data using OpenSSL (AES-256-CFB).
6. Does freezer execute point-in-time backup? Yes. For point in time backup LVM snapshot feature used.
7. Can I use freezer on OSX or other OS where GNU Tar is not installed by default? Yes. For OSX and *BSD, just install gtar and freezer automatically will use gtar to execute backup. OS other then Linux, OSX and *BSD are currently not supported.
8. What Application backup does freezer support currently? MongoDB and File system.
9. How does the MongoDB backup happens? Freezer required journal enabled in mongo and lvm volume to execute backup. It checks if the mongo instance is the master and create lvm snapshot to have consistent data.
10. Does freezer manage sparse files efficiently? Yes. Zeroed/null data is not backed up. So less space and bandwidth will be used.
11. Does freezer remove automatically backup after some time? Yes. From command line the --remove-older-then option (days) can be used to remove objects older then (days).
12. Does freezer support MySQL Backup? MySQL and MariaDB support soon will be included.
13. Is there any other storage media supported? Not currently. There's a plan to add:

• Amazon S3
• Store files on a remote host file system
• MongoDB object storage.
• Other directory in the local host (NFS mounted volumes)

14. Does freezer has any UI or API? Not currently. The UI in OpenStack Horizon is being currently developed as REST API too.
15. Tar is not capable to detect deleted files between different backup levels. Is freezer capable of doing that? Not currently. We are writing a set of tar extensions in python to overcome tar limitations like this and others.