Oracle Solaris Tunable Parameters Reference Manual



Controls the size of the duplicate request cache that detects RPC- level retransmissions on connectionless transports. This cache is indexed by the client network address and the RPC procedure number, program number, version number, and transaction ID. This cache avoids processing retransmitted requests that might not be idempotent.

Data Type

Integer (32-bit)




1 to 231 - 1




The cache is dynamically sized, but the hash queues that provide fast access to the cache are statically sized. Making the cache very large might result in long search times to find entries in the cache.

Do not set the value of this parameter to 0. This value prevents the NFS server from handling non idempotent requests.



When to Change

Examine the value of this parameter if false failures are encountered by NFS clients. For example, if an attempt to create a directory fails, but the directory is actually created, perhaps that retransmitted MKDIR request was not detected by the server.

The size of the cache should match the load on the server. The cache records non idempotent requests and so only needs to track a portion of the total requests. The cache does need to hold the information long enough to be able to detect a retransmission by the client. Typically, the client timeout for connectionless transports is relatively short, starting around 1 second and increasing to about 20 seconds.

Commitment Level