Solaris Tunable Parameters Reference Manual



Controls the logical block size used by the NFS version 4 client. This block size represents the amount of data that the client attempts to read from or write to the server when it needs to do an I/O.

Data Type

Unsigned integer (32-bit)


32,768 (32 Kbytes)


0 to 231 - 1




Yes, but the block size for a file system is set when the file system is mounted. To affect a particular file system, unmount and mount the file system after changing this parameter.


None. Setting this parameter too low or too high might cause the system to malfunction. Do not set this parameter to anything less than PAGESIZE for the specific platform. Do not set this parameter too high because it might cause the system to hang while waiting for memory allocations to be granted.

When to Change

Examine the value of this parameter when attempting to change the maximum data transfer size. Change this parameter in conjunction with the nfs:nfs4_max_transfer_size parameter. If larger transfers are preferred, increase both parameters. If smaller transfers are preferred, then just reducing this parameter should suffice.

Commitment Level