Milestone Basis+ 6.5 - Manual (Page 131)

Milestone XProtect Basis+ 6.5; Administrator’s Manual
Using 3 GB Operating System Virtual
Memory
Microsoft Windows 32-bit operating systems can address 4 GB of virtual memory. The operating
system kernel reserves 2 GB for itself, and each individual running process is allowed to address
another 2 GB. This is Windows’ default setting, and for the vast majority of XProtect Basis+
installations it works fine.
In XProtect Basis+ 6.5a or newer, the main components of the server—the Recording Server
service and the Image Server service—have been compiled with the LARGEADDRESSAWARE flag.
This means you can optimize the memory usage of XProtect Basis+’s Recording Server and Image
Server services by configuring your 32-bit Windows operating system so that it restricts the kernel
to 1GB of memory, leaving 3GB of address space for processes compiled with the LARGE-
ADDRESSAWARE flag.
This should improve the stability of especially the Recording Server service by allowing it to exceed
the previous 2 GB virtual memory limit, making it possible for it to use up to 3 GB of memory. The
change in Windows configuration is known as 3 GB switching.
When Is 3 GB Switching Relevant?
For very large XProtect Basis+ installations and/or for installations with many megapixel cameras it
can be relevant to change Windows’ settings so that only 1 GB of virtual memory is reserved for
the operating system kernel, leaving 3 GB for running processes.
If using Windows’ default setting, with only 2 GB virtual memory reserved for running processes, it
has been seen that the Recording Server service in very large installations of XProtect Basis+ may:
● Behave erratically if getting very close to the 2 GB virtual memory limit. Symptoms can
include database corruption, and client-server or camera-server communication errors.
● Become unstable and crash if exceeding the 2 GB virtual memory limit,. During such
crashes, the code managing the surveillance system databases is not closed properly, and
databases will become corrupt. In case of a crash, Windows will normally restart the
Recording Server service. However, when the Recording Server service is restarted, one of
its first tasks will be to repair the databases. The database repair process can in some cases
take several hours, depending on the amount of data in the corrupted databases.
If you experience such problems, and you run XProtect Basis+ 6.5a or newer, making Windows use
3 GB for running processes is likely to solve the problems.
If you have not experienced such problems, but you run XProtect Basis+ 6.5a or newer and your
XProtect Basis+ installation is very large and/or features many megapixel cameras, 3 GB switching
is likely to help prevent the problems from occurring.
What to Do
The way to configure 32-bit Windows to be LARGEADDRESSAWARE depends on your type of
Windows operating system. In the following, you will see to methods outlining Microsoft's
recommended procedure for increasing the per-process memory limit to 3 GB. Use the first method
if running Windows XP Professional or Windows Server 2003. Use the second method if running
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