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 snaps, but they can be configured to function with hardware snap engines.
For more information on the benefits of using block-level backups, see Block-Level Backups.
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
|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|
|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|
|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||39:03:04||4,068, 651|
|File-level restore from a full traditional backup||1.1 TB||46:00:00||4,068, 649|