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

system fails with error [ENOSPC] when the swap usage has reached the limit; in
addition, the following message will be displayed on the console:
memfs: Cumulative data exceeds memfs_swapmax_pct
This tunable can be modified dynamically. If the new limit specified is less than the
swap space in use by MemFS (for example 10%), following warning will be displayed
on console:
Warning: The specified value of tunable memfs_swapmax_pct is
less than the percentage of swap space currently in use by MemFS,
10 percent.
NOTE: The memfs_metamax and memfs_swapmax_pct tunables are dynamic on
HP-UX 11i v3 and can be modified without a system reboot.
Tuning memfs_metamax and memfs_swpmax_pct to a value less than the current
usage is not immediate always, though tunables are set with the new value, the current
usage may be more than the newly specified value. However, any operations that try
to allocate resources (kernel memory and system swap) will fail if the request goes
beyond the limit imposed by current value of the tunables.
2.2.3 Tools Support to Report MemFS Statistics
Tools sar(1m) and GlancePlus have been enhanced to provide the MemFS statistics
such as cumulative memory and swap space consumed by all the instances of MemFS.
These tools report memory/swap consumed in terms of 4096 bytes (4KB) only, even if
base_pagesize(5) tunable is tuned to higher values.
2.2.3.1 sar(1m)
SAR-MEMFS product reports MemFS statistics using sar(1M) command. The
SAR-MEMFS product provides a new option, -z that enables the sar(1M) command
to report MemFS data.
The -z option supports the following parameters:
• blkcnt
Specifies the number of MemFS blocks in the memory.
• swpcnt
Specifies the number of MemFS blocks in the swap.
For example:
# sar -z 1 10
HP-UX machine B.11.31 U ia64 11/26/08
15:39:59 blkcnt swpcnt15:40:00 30031 015:40:01 30031 015:40:02 30031
0
2.2 Tuning Memory File System 19