IBM SG24-4576-00 System Memory, New Packet Receive Buffer Wait Time, NetWare 3.12 Memory Pools

Recommendation

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For networks without wide area (WAN) segments, set the maximum packet receive buffers to 300.

For networks that use WANs, set the maximum packet receive buffers to 1000. This should be adequate to handle the additional buffering needed for WAN links.

5.3.2.4 New Packet Receive Buffer Wait Time

The new packet receive buffer wait time is the wait time taken before spawning a new packet receive buffer.

This parameter must be set in the AUTOEXEC.NCF file to change the value. The syntax is:

SET NEW PACKET RECEIVE BUFFER WAIT TIME=VALUE

For NetWare 3.12 and 4.1, the following is true:

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Default value = 0.1 second Range = 0.1-20 seconds

5.3.3 System Memory

The way in which NetWare manages system memory has a direct bearing on file server performance. Because of this, it is important to have an understanding of how the server allocates memory and the use of set parameters to control the system memory.

5.3.3.1 NetWare 3.12 Memory Pools

NetWare V3.12 is implemented as 32-bit code which means that it uses 32-bit addressing and the flat memory model. This gives it access to one flat segment of RAM of up to 4 GB in size. It loads the operating system, LAN and disk drivers and NLMs into one large flat memory space. When an application requests memory, the RAM is scanned for the first available block of memory large enough to accommodate the request.

NetWare V3.12 manages its RAM through the use of memory pools. These are designed to be allocated and optimized based on how they are used, long term or short term. Rather than pre-allocating a lot of memory at installation time, most resources are allocated on an as-needed basis. Any pre-assignment of memory is specified in the server′s STARTUP.NCF and AUTOEXEC.NCF files.

The table below shows the different NetWare memory pools and how they are used.

Table 19. NetWare Memory Pools
Memory Pool Name	Data Stored
Cache Buffers Pool	Cache files, data and applications
Cache Movable Memory Pool (non-fragmented)	NetWare inter FAT tables
Cache Non-movable Memory Pool (fragmented)	CLIB and NLMs
Permanent Memory Pool	Directory cache buffers, LSLs and Turbo FATs.
Alloc Memory Pool	Menu screens, connection tables, print queues
Semi-Permanent Memory Pool	LAN and disk controller drivers
	Chapter 5. Performance Tuning 185