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vxtune [-r] tunable
vxtune [-r] tunable value
You can use vxtune to display, set or change the memory tunables that are used by VVR. To maximize VVR performance, you can use this utility to experiment with different values before deciding on the optimal tunable values.
The main advantage of using vxtune to change tunable values is that the new values are available immediately without needing to reboot the system.
When invoked with no arguments, vxtune displays a list of the tunables whose values may be displayed or set.
When invoked with the name of a supported tunable as the argument, vxtune displays the value of that tunable.
When invoked with the name of a supported tunable and a value as arguments, vxtune attempts to set the tunable to that value.
The specified value can take the following prefixes as base specifiers:
- Value is in octal.
- Value is in hexadecimal.
By default, decimal is assumed.
The specified value can take the following suffixes as unit multipliers:
- g or G
- The specified value is in gigabytes.
- k or K
- The specified value is in kilobytes.
- m or M
- The specified value is in megabytes.
By default, the units are assumed to be bytes.
The values of the following memory tunables may be displayed or set:
The memory allocated for this cache is exclusively dedicated to it. It is not available for other processes or applications.
Setting the value of volpagemod_max_memsz below 512KB fails if cache objects or volumes that have been prepared for instant snapshot operations are present on the system.
If you do not use the FastResync or DRL features that are implemented using a version 20 DCO volume, the value of volpagemod_max_memsz can be set to 0. However, if you subsequently decide to enable these features, you can use vxtune to change the value to a more appropriate one.
Display the value of vol_min_lowmem_sz on a host:
Modify the value of vol_min_lowmem_sz to 2 megabytes on a host:
vxtune vol_min_lowmem_sz 2M
A non-zero exit code is not a complete indicator of the problems encountered but denotes the first condition that prevented further execution of the utility.
Do not delete the files /etc/vx/vxtunables or /etc/vx/vxtunables.template.
The vxtune command only affects the tunable values on the host on which it is run. If required, you must run the command separately on each host for which you want to change the tunable values (for example, for the log-owner node and any of its failover nodes in a cluster).
Values that have been specified using vxtune are not persistent across reboots. After you have determined the optimal value of a tunable using vxtune, you must use the platform-specific interface to set persistent values for the tunables.
Veritas Volume Replicator Planning and Tuning Guide
Veritas Volume Manager Administrator's Guide
Last updated: 28 Jul 2003
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