Caché Installation Guide - InterSystems Documentation

Calculating System Parameters for UNIX and Linux
Huge pages must be allocated contiguously, which may require a reboot. Therefore, to guarantee
the allocation, as well as to make the change permanent, do the following:
a. Enter a line in /etc/sysctl.conf file:
echo "vm.nr_hugepages=2056" >> /etc/sysctl.conf
b. Reboot the system.
c. Verify meminfo after reboot; for example:
[root woodcrest grub]# tail -4 /proc/meminfo
HugePages_Total: 2056
HugePages_Free: 2056
HugePages_Rsvd: 0
Hugepagesize: 2048 KB
3. Verify the use of Huge Pages by Caché.
Allocated 3580MB shared memory: 3000MB global buffers, 226MB routine buffers
The amount of memory available in Huge Pages should be greater than the total amount of shared
memory to be allocated; if it is not greater, Huge Pages are not used.
After Caché is started, meminfo should be checked again to verify that the HugePages_Rsvd:
value is close to the total amount of shared memory.
Note:
It is not advisable to specify HugePages_Total much higher than the shared memory
amount because the unused memory will not be available to other components.
B.1.2 Calculate Swap Space
The amount of swap space available on your system should never be less than the amount of real
memory plus 256 KB.
With this minimum in mind, InterSystems recommends the following value as the minimum amount
of swap space needed for Caché:
((# of processes + 4)† * (1024 KB)‡
+ total global buffer space
+ total routine buffer space
_____________________________________
= Minimum swap space
† Add 4 to the # of processes for the Caché Control Process, the Write daemon, the Garbage Collector,
and the Journal daemon. Also add 1 for each slave Write daemon. The # of processes must include all
user and jobbed processes which might run concurrently. If you are running networking, add 1 for the
RECEIVE system process plus the number of DMNNET daemons you have running (2 per port). If
your system is a server, add the number of DCP processes that will be created when all potential clients
access the server.
86 Caché Installation Guide