Veritas™ File System 5.0.1 Administrator's Guide

Types of Storage Checkpoints
You can create the following types of Storage Checkpoints:
■ Data Storage Checkpoints
■ nodata Storage Checkpoints
■ Removable Storage Checkpoints
■ Non-mountable Storage Checkpoints
Data Storage Checkpoints
A data Storage Checkpoint is a complete image of the file system at the time the
Storage Checkpoint is created. This type of Storage Checkpoint contains the file
system metadata and file data blocks. You can mount, access, and write to a data
Storage Checkpoint just as you would to a file system. Data Storage Checkpoints
are useful for backup applications that require a consistent and stable image of
an active file system. Data Storage Checkpoints introduce some overhead to the
system and to the application performing the write operation. For best results,
limit the life of data Storage Checkpoints to minimize the impact on system
resources.
See “Showing the difference between a data and a nodata Storage Checkpoint”
on page 95.
nodata Storage Checkpoints
A nodata Storage Checkpoint only contains file system metadata—no file data
blocks. As the original file system changes, the nodata Storage Checkpoint records
the location of every changed block. Nodata Storage Checkpoints use minimal
system resources and have little impact on the performance of the file system
because the data itself does not have to be copied.
In Figure 6-4, the first block originally containing A is updated.
The original data is not copied to the storage checkpoint, but the changed block
is marked in the Storage Checkpoint. The marker indicates which data has changed.
Storage Checkpoints
Types of Storage Checkpoints
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