Block-level backup is a faster method to back up data because only the extents that contain data are backed up, rather than the entire files.
Compared to file system backups and disk image-based backups, block-level backups reduce scan times when the file system has a large number of small files. Also, when compared to file system incremental backups, block-level incremental backups run faster and back up less data if the file system has very large files. Block-level backups might not be useful when backing up a portion of files or folders on a volume because block-level backups take a snapshot of the entire volume.
By default, block-level backups are performed using native snapshots, but they can be configured to function with hardware snapshot engines.
For more information on the benefits of using block-level backups, see Block-Level Backups.
Driverless Block-Level Backup
On UNIX computers, you can also run driverless block-level backups without having to load the CVBF driver in the kernel. This is especially useful on UNIX platforms where driver support is not available. For more information, see Driverless Block-Level Backups.
Performance Comparison
The following table compares performance metrics between traditional backups and block-level backups on Linux, using the Recursive Scan method with cataloging disabled.
Test data and system configuration details
Subclient content: Random set of unique files of 30 KB, 50 KB, and 80 KB sizes
|
Machine |
CPU |
RAM |
Swap |
Operating System Version |
|---|---|---|---|---|
|
Virtual machine - Linux client |
1 |
2 GB |
16 GB |
Red Hat Enterprise Linux 6.2 x86_64 |
|
Virtual machine - Linux MediaAgent |
12 |
16 GB |
16 GB |
Red Hat Enterprise Linux x86_64 |
|
Virtual machine - Windows CommServe |
8 |
16 GB |
16 GB |
Windows 2012 R2 |
|
Backups |
|||||
|---|---|---|---|---|---|
|
Backup Type |
Scan Time |
Backup Time |
Throughput GB/hr |
Application Size |
Number of Files |
|
Block-level backup (full) |
00:00:23 |
13:39:41 |
79.77 GB/hr |
1.05 TB |
4,064,572 |
|
Traditional backup (full) |
00:06:50 |
22:27:58 |
47.66 GB/hr |
1.05 TB |
4,064,572 |
|
Block-level backup (incremental) |
00:00:33 |
02:14:29 |
79.4 GB/hr |
177.2 GB |
19,111 files sized 8 MB each added, 14,051 files sized 8 MB each removed |
|
Traditional backup (incremental) |
00:08:16 |
01:48:47 |
73 GB/hr |
132.08 GB |
19,111 files sized 8 MB each added, 14,051 files sized 8 MB each removed |
|
Restores |
|||||
|
Restore Type |
Volume Size |
Restore Time |
Number of Files |
||
|
Volume-level restore from a full block-level backup |
1.1 TB |
13:49:51 |
|||
|
File-level restore from a full block-level backup |
1.1 TB |
46:00:00 |
4,068, 651 |
||
|
File-level restore from a full traditional backup |
1.1 TB |
39:03:04 |
4,068, 649 |
||
Test data and system configuration details
Subclient content: Random set of unique files of 30 KB, 50 KB, and 80 KB sizes
|
Machine |
CPU |
RAM |
Swap |
Operating System Version |
|---|---|---|---|---|
|
Virtual machine - Linux client |
1 |
2 GB |
16 GB |
Red Hat Enterprise Linux 6.2 x86_64 |
|
Virtual machine - Linux MediaAgent |
12 |
16 GB |
16 GB |
Red Hat Enterprise Linux x86_64 |
|
Virtual machine - Windows CommServe |
8 |
16 GB |
16 GB |
Windows 2012 R2 |