Memory File System (MemFS) 2.0 for HP-UX 11i v3

M=1000000, MB=(1024*1024), and GB=(1024*1024*1024). For example, a constant
value could be 500K.
Example:
kctune -s memfs_metamax=100MB
If MemFS utilizes all the memory specified by this tunable, mounting of new MemFS
file systems and creation of new files on them will fail and following message will be
displayed on console:
memfs: metadata exceeds memfs_metamax
This tunable can be modified dynamically. If the new limit specified is less than the
memory in use by MemFS metadata (for example 20480 bytes), following warning will
be displayed on console:
Warning: The specified value of tunable memfs_metamax is less
than the amount of memory currently in use by MemFS, 20480 bytes.
2.2.2 memfs_swapmax_pct
The memfs_swapmax_pct tunable defines the maximum amount of system swap
space that can be used by all MemFS instances in a system as percentage of total system
swap configured in a system. The tunable does not reserve or assure the swap space
of specified size; it just assures that the swap space usage by MemFS does not grow
beyond the specified size. The value of this tunable can be as low as 0% of system swap
or as high as 80% of system swap. The default value is 50% of system swap.
Tunable values can be specified as follows:
1. Default
Example:
kctune -s memfs_swapmax_pct=Default
2. A percentage of total swap space; a positive whole number (0-80)
Example:
kctune -s memfs_swapmax_pct=60
Data in MemFS files share the system swap device used by others. Therefore, it is
important to define a value for this tunable that balances MemFS swap usage and usage
for the rest of the system. If the value is too low, then applications can not issue those
writes which results in new block allocations to write data to MemFS files. Tuning this
tunable too high and if MemFS file systems have huge data, can reduce the amount of
swap space available to other applications and will negatively impact system
performance or applications might fail because of low swap condition.
The value of memfs_swapmax_pct may need to be raised on systems with a large
amount of data used for MemFS file systems. Writing of data to a file in MemFS file
18 Installing, Configuring, Tuning, and Removing HP-UX Memory File System