qioadmin(1)qioadmin(1)NAMEqioadmin - VxFS Quick I/O for Databases cache administration utility
SYNOPSIS
/opt/VRTS/bin/qioadmin [ -p listfile ] [ -P filename,... ] [ -s qiotab
] [ -S filename={ ON | OFF | on | off }...] [mount_point]
AVAILABILITY
VRTSvxfs
DESCRIPTION
The VERITAS Quick I/O for Databases feature combines the advantages of
raw I/O and file I/O to improve database transaction processing perfor‐
mance. Cached Quick I/O further improves database performance on
machines with sufficient memory by caching data in the file system
cache. On 32-bit systems, for example, databases can only use up to 4
GB of the memory for their database cache because of the 32-bit address
space limitation, so for read operations, Cached Quick I/O stores data‐
base blocks in file system cache. This reduces the number of physical
I/O operations required.
On 64-bit systems, where limited memory addressing is not a critical
problem, using the file system caching still increases performance by
taking advantage of the read-ahead functionality. To maintain the cor‐
rect data in the buffer for write operations, Cached Quick I/O keeps
the buffer cache in sync with the data written to disk.
mount_point can be either a prefix to a relative path name when qiotab
is not specified, or can select a particular device in qiotab.
Enabling Caching
There are two components to enabling Cached Quick I/O. First, caching
must be enabled on the file system, second, caching must be enabled on
individual files in the file system. By default, Cached Quick I/O on a
file system is initially disabled.
You can enable Cached Quick I/O on a file system by setting the tunable
parameter qio_cache_enable=1 of vxtunefs (see the vxtunefs(1M) manual
page). After setting the qio_cache_enable parameter, caching is
enabled for all files in the file system. You can then turn caching
off, or on again, on a per-file basis using qioadmin. The
qio_cache_enable parameter is not persistent across mounts, returning
to its default value when the file system is unmounted. You can make
the qio_cache_enable parameter persistent across mounts by modifying
the tunefstab file (see the tunefstab(4) manual page).
The qioadmin cache advisories operate only if Cached Quick I/O is
enabled for the file system. If the qio_cache_enable flag is zero,
Cached Quick I/O is OFF for all the files in that file system even if
the individual file cache advisory for a file is ON. The per-file
cache advisories are not persistent across mounts, returning to their
default values when the file system is unmounted. You can use the
qiotab file to make the cache advisory settings permanent.
For more information on how to use Cached Quick I/O, see the VERITAS
File System Administrator's Guide and the VERITAS Storage Foundation
for databases documentation.
qiotab Format
/etc/vx/qioadmin is the default qiotab file for Cache Quick I/O advi‐
sories. When the file system is mounted, entries in /etc/vx/qioadmin
are processed and the advisories are set on the listed files. qiotab
contains a series of entries in the format shown below.
device=block_device
Where block_device is the block device used to mount a file system.
The device= entry indicates the start of files belonging to a particu‐
lar file system. All the files that follow the device= entry belong to
the file system mounted on the specified device. The second device=
entry delineates the end of files on one device and the start of files
on another device.
The following qiotab example shows the list of files to cache in the
file systems /database01 and /database02. For /database01, cust.dbf
and system.dbf have Cached Quick I/O turned off, while cust.dbf has
Cached Quick I/O turned on. For /database02, emp.dbf has Cached Quick
I/O turned on, while history.dbf has Cached Quick I/O turned off.
device=/dev/vx/dsk/datadg/database01
cust.dbf,off
system.dbf,off
stk.dbf,on
device=/dev/dsk/c3t0d0s4/database02
emp.dbf,on
history.dbf,off
Cluster File System Issues
Quick I/O works on VxFS cluster file systems, but Cached Quick I/O is
not currently supported.
OPTIONS
The default behavior is to set the caching advisories on a file system
from the default qiotab file /etc/vx/qioadmin.
-p listfile
Prints the caching advisories for the files listed in the
file listfile. The file names can be path names relative to
the mount point or absolute path names.
-P filename,...
Prints the current caching advisories for the files listed on
the command line. The file names can be path names relative
to the mount point or absolute path names.
-s qiotab Sets the caching advisories on the files based on entries in
qiotab. If a mount_point is specified, -s selects a particu‐
lar device and all associated files from the qiotab file. If
no mount_point is specified, -s selects all devices and asso‐
ciated files listed in the qiotab file.
-S filename={ON|OFF|on|off}...
Sets the caching advisories using the list of files from the
command line. filename can be an absolute path name or a
path name relative to the mount point. Setting the value to
ON (or on) turns on caching if the qio_cache_enable option of
vxtunefs is set for the file system. Setting it to OFF (or
off) turns caching off.
FILES
/etc/vx/qioadmin Default qiotab file.
SEE ALSOqiomkfile(1), qiostat(1), vxtunefs(1M)
The VERITAS File System Administrator's Guide and the VERITAS Storage
Foundation for databases documentation. have more detailed informa‐
tion.
VxFS 5.0 7 Jan 2008 qioadmin(1)