Service manual

Sizing Physical Memory
Chapter 4 Hardware Sizing 83
To estimate approximate memory size, perform the following steps.
1. Estimate the base size of the server process, slapdBase.
slapdBase = 75 MB +(nsslapd-threadnumber x 0.5 MB) +(nsslapd-maxconnections x 0.5 KB)
2. Determine the sum of entry cache sizes, entryCacheSum.
entryCacheSum = Sum
all entry caches
(nsslapd-cachememsize)
3. Determine the total size for all caches, cacheSum.
cacheSum = entryCacheSum + nsslapd-dbcachesize + nsslapd-import-cachesize
4. Determine the total size for the Directory Server process, slapdSize.
slapdSize = slapdBase + cacheSum
You may use utilities such as pmap(1) on Solaris systems or the Windows Task
Manager to measure physical memory used by Directory Server.
5. Estimated memory needed to handle incoming client requests, slapdGrowth.
slapdGrowth = 20% x slapdSize
As a first estimate, we assume 20 percent overhead for handling client
requests. The actual percentage may depend on the characteristics of your
particular deployment. Validate this percentage empirically before putting
Directory Server into production.
6. Determine total memory size for Directory Server, slapdTotal.
slapdTotal = slapdSize + slapdGrowth
For large deployments involving 32-bit servers, slapdTotal may exceed the
practical limitofabout 3.4GB, and perhapseven thetheoretical process limitof
about 3.7 GB. In this case, you may choose either to tune caching as suggested
in Chapter 6, “Tuning Cache Sizes,” to work within the limits of the system, or
to use a 64-bit version of the product.
Sizing Memory for the Operating System
Estimating the memory needed to run the underlying operating system must be
doneempirically,as operating system memoryrequirements vary widelybased on
the specifics of the system configuration. For this reason, consider tuning a
representative system for deployment as described in Chapter 5, “Tuning the
Operating System,” before attempting to estimate how much memorythe
underlying operating system needs. After tuning the system, monitor memory use
to arrive at an initial estimate,
systemBase. You may use utilities such as sar(1M)
on Solaris systems or the Task Manager on Windows to measure memory use.