Veritas Storage Foundation 5.1 SP1 Cluster File System Administrator"s Guide (5900-1738, April 2011)

The number of parallel fsck threads that could be active during recovery was set
to 4. For example, if a node failed over 12 file systems, log replay for the 12 file
systems will not complete at the same time. The number was set to 4 since parallel
replay of a large number of file systems would put memory pressure on systems
with less memory. However, on larger systems the restriction of 4 parallel
processes replaying is not necessary.
This value gets tuned in accordance with available physical memory in the system.
To set the number of parallel fsck threads
◆
On all nodes in the cluster, edit the
/opt/VRTSvcs/bin/CFSfsckd/CFSfsckd.env file and set FSCKD_OPTS="-n
N".
where N is the number of parallel fsck threads desired and value of N has to
be between 4 and 128.
Note: The default number of parallel fsck threads is determined by the amount
of memory on the machine, unless overridden by the user.
About Storage Checkpoints
Veritas File System (VxFS) provides a Storage Checkpoint feature that quickly
creates a persistent image of a file system at an exact point in time. Storage
Checkpoints significantly reduce I/O overhead by identifying and maintaining
only the file system blocks that have changed since the last Storage Checkpoint
or backup via a copy-on-write technique.
Storage Checkpoints provide:
■ Persistence through reboots and crashes.
■ The ability for data to be immediately writeable by preserving the file system
metadata, the directory hierarchy, and user data.
Storage Checkpoints are actually data objects that are managed and controlled
by the file system. You can create, remove, and rename Storage Checkpoints
because they are data objects with associated names.
Unlike a disk-based mirroring technology that requires a separate storage space,
Storage Checkpoints minimize the use of disk space by using a Storage Checkpoint
within the same free space available to the file system.
After you create a Storage Checkpoint of a mounted file system, you can also
continue to create, remove, and update files on the file system without affecting
the logical image of the Storage Checkpoint. A Storage Checkpoint preserves not
25Storage Foundation Cluster File System architecture
About Storage Checkpoints