You can modify certain kernel parameters to improve system performance and allocate resources more effectively. The optimum setting for kernel parameters is often determined by a system’s hardware configuration and the specific mix of applications running on the system. Hewlett-Packard attempts to provide reasonable default settings, but you can modify these values to improve performance based on your system’s particular needs. Before modifying the value of any parameter, be sure you understand the implications of a change. Many kernel parameters interact with each other, so selecting values should always be done in a balanced manner. Changing kernel parameters to improper values can lead to data loss, system panics, or other operating anomalies that are difficult to diagnose. The table below shows the recommended parameter settings for N- and V-Class servers running under HP-UX 11.0. Parameter Name STRMSGSZ Default Setting 0 swapmem_on 1 Recommended Setting 65535 0 vps_ceiling 16 64 shmmax 0x4000000 0x7B000000 nstrpty calculated 60 maxusers 32 250 maxswapchunk 256 s 16384 maxdsiz 0xF6000000 0x4000000 maxdsiz_64bit 0x40000000 0xF6000000 Description Maximum number of bytes that can be sent in the data part of a STREAMS message using the function putmsg and write. If STRMSGSZ is 0, the maximum data message size is infinite. Allows the oversubscription of swap so applications can run that cannot allocate swap space (for example, when memory is smaller than swap). swapmem_on is enabled for 16G servers. However, it appears to take memory away from the free list if swap is not big enough. Maximum variable page size should be higher on VClass servers due to a larger cache. This allows up to 64K pages. Maximum use of shared memory. Number of STREAMS-based pseudo-terminals. The maxusers default is too small for large memory systems. The value of maxusers is used to calculate other parameters. Maximum value. The value of maxswapchunks only needs to be large enough to handle the swap space. The maxdsiz default is too small for large memory systems. The maxdsiz_64bit default is too small for large memory systems. Be careful, however, when setting the value larger then memory; otherwise, applications can run into trouble. 0x005000000 The maxssize default is too small for large memory systems. maxssiz_64bit 0x800000 0x5000000 The maxssize_64bit default is too small for large memory systems. lotsfree 131072 maxssiz 0x800000 0 Upper bound from which the paging daemon will begin stealing pages. Must be set by editing the /stand/system file instead of using SAM. minfree desfree ninode 0 0 calculated (1818) 8192 32768 8000 Minimal amount of free memory that is tolerable. If free memory drops below this amount, the system begins deactivating processes. Must be set by editing the /stand/system file instead of using SAM. Desired amount of free memory. This is the lower bound at which the paging daemon begins stealing pages. Must be set by editing the /stand/system file instead of using SAM. Provides more space for the inode cache—this is good for NFS or other servers that open or stat many files frequently. For heavily-loaded NFS servers, set the value of ninode between 100000 and 200000.