PFSServers Section

A PFS I/O server is a Sun HPC node that is connected to one or more disk storage units that are defined as part of a parallel file system in the hpc.conf file--that is, they are listed in a PFSFileSystem section of the hpc.conf file. Plus, the node itself must be listed in the PFSServers section of hpc.conf, as shown in Example 2-6.

Example 2-6 PFSServers Section Example

Begin PFSServers
NODE            BUFFER_SIZE
hpc-node0        150
hpc-node1        150
hpc-node2        300
hpc-node3        300
End PFSServers

In addition to being defined in hpc.conf, a PFS server also differs from other nodes in a Sun HPC cluster in that it has a PFS I/O daemon running on it.

PFS I/O Server Hostnames

The left column lists the hostnames of the nodes that are PFS I/O servers. In this example, they are hpc-node0 through hpc-node3.

Buffer Size

The second column specifies the amount of memory the PFS I/O daemon will have for buffering transfer data. This value is specified in units of 32-Kbyte buffers. The number of buffers that you specify will depend on the amount of I/O traffic you expect that server is likely to experience at any given time.

The optimal buffer size will vary with system type and load. Buffer sizes in the range of 128 to 512 provide reasonable performance on most Sun HPC Systems. You can use pfsstat to get reports on buffer cache hit rates. This can be useful for evaluating how well suited the buffer size is to the cluster's current I/O activity.