Veritas File System 5.1 SP1 Administrator"s Guide (5900-1499, April 2011)

is blocked at the system call level. Current operations are completed and the file
system is synchronized to disk.
When the file system is frozen, any attempt to use the frozen file system, except
for a VX_THAW ioctl command, is blocked until a process executes the VX_THAW ioctl
command or the time-out on the freeze expires.
Getting the I/O size
VxFS provides the VX_GET_IOPARAMETERS ioctl to get the recommended I/O sizes
to use on a file system. This ioctl can be used by the application to make decisions
about the I/O sizes issued to VxFS for a file or file device.
See the vxtunefs(1M) and vxfsio(7) manual pages.
See “Tuning I/O” on page 52.
Enabling and disabling Concurrent I/O for a DB2
database
Concurrent I/O is not turned on by default and must be enabled manually. You
must manually disable Concurrent I/O if you choose not to use it in the future.
Enabling Concurrent I/O
Because you do not need to extend name spaces and present the files as devices,
you can enable Concurrent I/O on regular files.
Before enabling Concurrent I/O, review the following information:
■ To use the Concurrent I/O feature, the file system must be a VxFS
file system.
■ Make sure the mount point on which you plan to mount the file
system exists.
■ Make sure the DBA can access the mount point.
Prerequisites
Enabling Concurrent I/O on a file system using mount with the
-o cio option
You can enable Concurrent I/O by using mount with the -o cio option.
To enable Concurrent I/O on a file system using mount with the -o cio option
◆
Mount the file system using the -o cio option:
Veritas File System I/O
Getting the I/O size
74