Veritas File System 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Storage Checkpoints
Space Management Considerations
Chapter 5 93
Space Management Considerations
Several operations, such as removing or overwriting a file, can fail when a file system containing Storage
Checkpoints runs out of space. Usually these operations do not fail because of insufficient space on the file
system, but these operations on a file system containing Storage Checkpoints can cause a data block copy
that, in turn, may require extent allocation. If the system cannot allocate sufficient space, the operation will
fail.
Database applications usually preallocate storage for their files and may not expect a write operation to fail.
If a file system runs out of space, the kernel automatically removes Storage Checkpoints and attempts to
complete the write operation after sufficient space becomes available. The kernel removes Storage
Checkpoints to prevent commands, such as rm (see the rm(1) manual page), from failing under an
out-of-space (ENOSPC) condition.
The kernel will follow these policies when automatically removing Storage Checkpoints:
• Remove as few Storage Checkpoints as possible to complete the operation.
• Never select a non-removable Storage Checkpoint.
• Select a nodata Storage Checkpoint only when data Storage Checkpoints no longer exist.
• Remove the oldest Storage Checkpoint first.