Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

Table 16-1
Kernel tunable parameters for VxVM (continued)
DescriptionParameter
The maximum size of logical I/O operations that can be
performed without breaking up the request. I/O requests to
VxVM that are larger than this value are broken up and
performed synchronously. Physical I/O requests are broken
up based on the capabilities of the disk device and are
unaffected by changes to this maximum logical request
limit.
The default value is 2048 sectors (2048KB).
The value of voliomem_maxpool_sz must be at least 10
times greater than the value of vol_maxio.
If DRL sequential logging is configured, the value of
voldrl_min_regionsz must be set to at least half the
value of vol_maxio.
vol_maxio
The maximum size of data that can be passed into VxVM
via an ioctl call. Increasing this limit allows larger
operations to be performed. Decreasing the limit is not
generally recommended, because some utilities depend upon
performing operations of a certain size and can fail
unexpectedly if they issue oversized ioctl requests.
The default value is 32768 bytes (32KB).
vol_maxioctl
The number of I/O operations that the vxconfigd daemon
is permitted to request from the kernel in a single
VOL_VOLDIO_READ per VOL_VOLDIO_WRITE ioctl call.
The default value is 256. This value should not be changed.
vol_maxparallelio
Performance monitoring and tuning
Tuning VxVM
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