Create PFS I/O Servers

Decide which cluster nodes that you want to have function as PFS I/O servers. To be of value as PFS I/O servers, these nodes must be connected to one or more disk storage devices that have enough capacity to handle the PFS file systems you expect will be stored on them.

The disk storage units should include some level of RAID support to protect the file systems against failure of individual storage devices.

Once you know which nodes you want as I/O servers, list their host names on separate lines in the PFSServers section of hpc.conf. Example 3-2 shows a sample PFSServers section that includes three PFS I/O server nodes.

Example 3-2 PFSServers Section Example

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

The left column lists the host names of the PFS I/O server nodes.

The second column specifies the amount of memory the PFS I/O daemon will have available for buffering transfer data. This value is specified in units of 32-Kbyte buffers. The number of buffers that you should 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. Knowing buffer cache hit rates can be useful for evaluating how well suited the buffer size is to the cluster's current I/O activity.