nfs:nrnode Parameter

Description

Controls the size of the rnode cache on the NFS client.

The rnode, used by NFS version 2, 3, and 4 clients, is the central data structure that describes a file on the NFS client. The rnode contains the file handle that identifies the file on the NFS server. The rnode also contains pointers to various caches used by the NFS client to avoid network calls to the server. Each rnode has a one-to-one association with a vnode. The vnode caches file data.

The NFS client attempts to maintain a minimum number of rnodes to attempt to avoid destroying cached data and metadata. When an rnode is reused or freed, the cached data and metadata must be destroyed.

Data Type

Integer (32-bit)

Default

The default setting of this parameter is 0, which means that the value nrnode should be set to the value of the ncsize parameter. Actually, any non positive value of nrnode results in nrnode being set to the value of ncsize.

Range

1 to 2³¹ - 1

Units

rnodes

Dynamic?

No. This value can only be changed by adding or changing the parameter in an /etc/system.d/file , and then rebooting the system.

Validation

The system enforces a maximum value such that the rnode cache can only consume 25 percent of available memory.

When to Change

Because rnodes are created and destroyed dynamically, the system tends to settle upon a nrnode-size cache, automatically adjusting the size of the cache as memory pressure on the system increases or as more files are simultaneously accessed. However, in certain situations, you could set the value of nrnode if the mix of files being accessed can be predicted in advance. For example, if the NFS client is accessing a few very large files, you could set the value of nrnode to a small number so that system memory can cache file data instead of rnodes. Alternately, if the client is accessing many small files, you could increase the value of nrnode to optimize for storing file metadata to reduce the number of network calls for metadata.

Although it is not recommended, the rnode cache can be effectively disabled by setting the value of nrnode to 1. This value instructs the client to only cache 1 rnode, which means that it is reused frequently.

Commitment Level

Unstable