Veritas InfoScale™ 7.3.1 What's New In This Release - AIX, Linux, Solaris
- What's new in this release
- Changes related to installation and upgrades
- Changes related to Cluster Server agents
- Changes related to Veritas File System
- Changes related to Veritas Volume Manager
- Changes related to replication
- Changes related to operating systems
- Changes related to Dynamic Multipathing
Delayed allocation support extended to clustered file systems
The delayed allocation capability for extending writes on a file system was available for local mounts. This capability is now extended for clustered file systems (CFS mounts).
With this support, depending on an application I/O size, instead of allocating a single block for every write operation a clustered file system will now allocate multiple blocks in a single instance. The delayed allocation thus reduces the file system fragmentation.
When an application I/O is received, the delayed allocation capability enables the clustered file system to spilt the write operation in to the following sequence:
Reserve a disk space
When an application I/O is received, the file system first reserves a disk space and the data is cached.
Allocate extents
After a disk space is reserved, a scheduler allocates disk blocks at the background and the file system then combines multiple block allocation requests to allocate extents.
The delayed extent allocation thus helps to avoid file system fragmentation and keeps the extent contiguous even if several files grow at the same time.
The delayed allocation is not dependent on the file system disk layout version and is disabled by default. You can enable delayed allocation using the vxtunefs command. You can display the delayed allocation range in the file by using the fsmap command.
See the vxtunefs(1M) and fsmap(1M) manual pages.
Notes:
Delayed allocation must be disabled in cases where the data must be immediately written to the disk. For example, direct I/O, concurrent I/O, FDD/ODM access, and synchronous I/O.
Delayed allocation is not supported on memory-mapped files, BSD quotas, and shared mount points in a Cluster File System (CFS).
When BSD quotas are enabled on a file system, delayed allocation is turned off automatically for that file system.