Benefits of copy-on-write versus mirror

Table: Comparative benefits of copy-on-write and mirror compares the benefits of the two types of snapshots.

Table: Comparative benefits of copy-on-write and mirror

Benefits of copy-on-write	Benefits of mirror
It consumes less disk space: No need for secondary disks containing complete copies of source data. Relatively easy to configure (no need to set up mirror disks). Creates a snapshot much faster than one created by a large, unsynchronized mirror, because mirror synchronization can be time consuming.	It has less effect on the performance of the host being backed up (NetBackup client), because the copy-on-write mechanism is not needed. Allows for faster backups: The backup process reads data from a separate disk (mirror) operating independently of the primary disk that holds the client's source data. Unlike copy-on-write, disk I/O is not shared with other processes or applications. Apart from NetBackup, no other applications have access to the mirror disk. During a copy-on-write, other applications as well as the copy-on-write mechanism can access the source data. Note: If additional disk drives are available and volumes have been configured with the Veritas Volume Manager, a mirror snapshot method is usually a good choice.

Benefits of copy-on-write

Benefits of mirror

It consumes less disk space: No need for secondary disks containing complete copies of source data.
Relatively easy to configure (no need to set up mirror disks).
Creates a snapshot much faster than one created by a large, unsynchronized mirror, because mirror synchronization can be time consuming.

It has less effect on the performance of the host being backed up (NetBackup client), because the copy-on-write mechanism is not needed.
Allows for faster backups: The backup process reads data from a separate disk (mirror) operating independently of the primary disk that holds the client's source data. Unlike copy-on-write, disk I/O is not shared with other processes or applications. Apart from NetBackup, no other applications have access to the mirror disk. During a copy-on-write, other applications as well as the copy-on-write mechanism can access the source data.

Note:

If additional disk drives are available and volumes have been configured with the Veritas Volume Manager, a mirror snapshot method is usually a good choice.

See About the copy-on-write snapshot type.

See About the mirror snapshot type.

More Information

About snapshot basics

Benefits of copy-on-write versus mirror

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