There is NO physical limit in Windows NT 4.0.

As you add users, groups, and computers to a domain, the size of the SAM (Security Accounts Manager) database increases, affecting performance. If you have a computer which acts as a domain controller (with no other major NT services running, such as File & Print, RAS, DHCP, WINS, DNS, SQL, SNA, and Exchange), you can use the following table as a guideline:


Number SAM Registry PagedPool CPU Paging RAM
of users size size size needed file size

10,000 15 25 (default) 50 (default) P or A 128 64
15,000 20 30 75 P or A 128 64
20,000 30 50 100 P or A 256 128
30,000 45 75 128 P or A 332 166
40,000 60 102 128 SMP 394 197
50,000 75 102 128 SMP 512 256
60,000 80 102 128 SMP 1Gb 512
As the size of the domain increases, monitor:

* System Boot time, which increases as the system pages in the entire account database.

* Time to create a group, which increases as the total SAM size grows very large.

* Time to add users to a large group, which increases as the SAM grows above 60 MB.

* Bandwidth required to replicate a large SAM.

NOTE: P=Pentium, A=ALPHA, SMP=Multi-Processor.

NOTE: Add RAM to improve performance.

NOTE: Processor speed only becomes important as you add other services and functions.

NOTE: Add RAM as you add services and functions.

NOTE: Add RAM as you add services and functions.

NOTE: Add RAM as you add services and functions.

NOTE: Add RAM as you add services and functions.

NOTE: Add RAM as you add services and functions.

NOTE: Add RAM as you add services and functions.