Veritas 5.0.1 Installation Guide HP-UX 11i v3 (5900-2464, September 2012)

it. The SmartMove feature uses VxFS information to detect free extents and avoids copying
them.
• Dynamic Storage Tiering Enhancements
The Dynamic Storage Tiering (DST) feature provides the following enhancements:
◦ Enhanced DST APIs to provide a new interface for managing allocation policies of storage
checkpoints during creation and later, and for managing named data stream allocation
policies
◦ fsppadm support for user ID (UID), group ID (GID), and tagging (TAG) elements in the
placement policy XML file
◦ Improved scan performance in the fsppadm command
◦ Suppressed processing of the chosen RULE
◦ Parser support for UID, GID, and TAG elements in a DST policy
◦ What-if support for analyzing and enforcing without requiring the policy to be assigned
◦ Storage Checkpoint data placement support in a DST policy
◦ Shared DB thread handle support
◦ CPU and I/O throttling support for DST scans
◦ New command, fstag, for file tagging
◦ New command, fsppmk, for creating XML policies
• Availability of the mntlock and mntunlock Mount Options
You can specify the mntlock option with the mount command to prevent a file system from
being unmounted by an application.
VxFS 5.0.1 on HP-UX 11i v3
For more information on features supported with VxFS 5.0.1 on HP-UX 11i v3, see Veritas File
System 5.0.1 Release Notes at http://docs.hp.com.
Architecture of VxFS
HP-UX supports various file systems. In order for the kernel to be able to access these different file
system types, there is a layer of indirection above them called Virtual File System (VFS).
Without the VFS layer, the kernel must know the specifics of each file system type and maintain
distinct code to handle each.
The VFS layer enables the kernel to possess a single set of routines that are common to all file
system types. Handling of the specifics of a file system type are passed down to the file system
specific modules. The following sections describe the VxFS file system specific structures.
The following are the VxFS on-disk structures:
• Superblock
A superblock (SB) resides ~8k from the beginning of the storage and tracks the status of the
file system. It supports maps of free space and other resources (inodes, allocation units, and
so on).
• Intent Log
VxFS reduces system failure recovery time by tracking file system activity in the VxFS intent
log. This feature records pending changes to the file system structure in a circular intent log.
Veritas File System (VxFS) 19