Veritas Volume Manager (VxVM) provides throttling of administrative I/O. During heavy I/O loads, VxVM throttles I/O that it creates to do administrative operations. This behavior ensures that the administrative I/Os do not affect the application I/O performance. When the application I/O load is lighter, VxVM increases the bandwidth usage for administrative I/O operations.
VxVM automatically manages the I/O throttling for administrative tasks, based on its perceived load on the storage. Currently, I/O throttling is supported for the copy operations which use ATOMIC_COPY and involve one destination mirror. The I/O throttling is transparent, and does not change the command usage or output. The following commands are supported:
The administrative I/O operations allocate memory for I/O from a separate memory pool. You can tune the maximum size of this pool with the tunable parameter, vol_max_adminio_poolsz.
For example, to change the vol_max_adminio_poolsz parameter to 256MB, use tbe following command:
# vxtune vol_max_adminio_poolsz 256M
See the Storage Foundation Tuning Guide for information about tuning the vol_max_adminio_poolsz parameter.