nbuf
nbuf sets the system-wide number of file-system buffer and
cache buffer headers (determines maximum total number of buffers on the
system). See note below.
0 or 16
0
Specify integer value of zero (see below). For more information, see Specifying Parameter Values.
This parameter is for backwards compatibility and should be set to zero because dynamic buffer cache is preferred. See Configurable File-System Buffer Parameters and Overview of File-System Configurable Parameters for more information.
If set to a non-zero value, nbuf specifies the number of
buffer headers to be allocated for the file system buffer-cache. Each
buffer is allocated 4096 bytes of memory unless overridden by a
conflicting value for
bufpages.
If nbuf is set to a non-zero value that is less than 16 or
greater than the maximum supported by the system, or to a value that is
inconsistent with the value of bufpages, the number will be
increased or decreased as appropriate, and a message printed at boot
time.
nbuf interacts with bufpages as follows:
bufpages = 0, nbuf = 0: Enables
dynamic buffer cache.
bufpages not zero, nbuf = zero:
Creates BufPages/2 buffer headers and allocates
bufpages times 4 Kbytes of buffer pool space at
system boot time.
bufpages = 0, nbuf not zero: Allocates
Nbuf*2 pages of buffer pool space and creates
Nbuf headers at boot time..
bufpages not zero, nbuf not zero:
Allocates BufPages pages of buffer pool space and
creates Nbuf buffer headers at boot time. If the
two values conflict such that it is impossible to configure a
system using both of them, bufpages takes
precedence.
bufpages controls the
actual memory allocated to the buffer pool.