freezer/FAQ.rst

FAQ

1. What is freezer? Is a tool to automate data backup and restore process using OpenStack Swift and/or other media storage
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? 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 > 400GB and hundreds 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. Rsync backup type will be added pretty soon
5. Does freezer 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, MySQL to have a higher level of data consistency, while any appplication is supported for crash consistent data integrity.
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 option --remove-older-then (days) can be used to remove objects older then (days).
12. Does freezer support MySQL Backup? Yes.
13. What storage media are currently supported? Current support media storage are:
    1. Swift
    2. Store files on a remote host file system using ssh
    3. Directory in the local host (i.e. NFS/CIFS mounted volumes)
14. Does freezer has any Web UI or API? Yes. Freezer has REST API and a Web UI integrated with Horizon
15. Does Freezer detect removed files between incremental executions? Yes.
16. Will Freezer be included as official project in OpenStack? We hope so, as soon as we can.
17. Does freezer support Windows? Yes. The freezer agent and scheduler can be executed on Windows
18. What is being used on Windows to execute file system snapshots? Curretnly VSS are used to support point in time snapshots
19. What applications are supported in Windows for consisten backups? SQL Server (--mode sqlserver)