1200 databases, an os, and possibly other stuff? Yeah, I think the server itself is going to need more than 1gb of ram to function, especially considering that, if you set 15gb as SQL Server's max memory setting, it still needs additional memory outside of that 15gb for threads.
I'd bump SQL Server down to 14gb to give the server a little more breathing room.
Also, an example given in "Professional SQL Server 2008 Internals and Troubleshooting" for memory allowances on a SQL Server 2008 x64 system with third-part backup utility with 16GB RAM:
- 2 GB for Windows
- 1GB for worker threads
- 1GB for MPAs, etc.
- 1GB for the backup program
- 11GB for SQL Server
In the book it shows how to determine the max number of threads you can have, and how to calculate how much memory they'll take up. Run this (change the server type to match your server) to figure out how much memory your threads will need.
declare @servertype int
set @servertype=1
/*
1: x86 (32-bit)
2: x64 (64-bit)
3: IA64
*/
select max_workers_count *
(
case @servertype when 1 then .5
when 2 then 2
when 3 then 4
else .5
end
)
from sys.dm_os_sys_info