In this series of posts I’ll be describing several settings and parameters that can be tuned to optimize your server performance. I hope you’ll find them useful and help you improve your servers performance.
- Performance Tuning your Windows Server (Part 2)
- Performance Tuning your Windows Server (Part 3)
- Performance Tuning your Windows Server (Part 4)
Note: As with all changes, you should implement the following suggestions one at a time and verify that there was a performance improvement. If system performance decreases after making a change, you should reverse the change.
Windows uses multitasking to prioritize process threads that the CPU has to handle. The execution of a process is halted and another is started, preventing a single thread from monopolizing the entire CPU.
Switching the CPU from executing one process to the next is known as context-switching. The Windows operating system includes a setting that determines how long individual threads are allowed to run on the CPU before a context-switch occurs and the next thread is serviced.
Typically for a server, it is not desirable to allow the foreground program to have more CPU time allocated to it than background processes. That is, all applications and their processes running on the server should be given equal contention for the CPU.
To set this, Open the System Control Panel, select the Advanced tab, in the Performance frame click Settings, go to the Advance tab, and within the Processor Scheduling frame, set the Adjust for best performance of: to Background Services.
The file system cache is an area of physical memory set aside to dynamically store recently
accessed data that has been read or written from or to the I/O subsystem (hard drives, networks interfaces, and networks). The file system cache improves performance by reducing the number of accesses to physical devices attached to the I/O subsystem, by moving commonly used files into system cache, disk and network read and write operations are reduced and system performance is increased. You can optimize Windows server performance by tuning the file system cache.
System Cache: This option is the default setting. It instructs the operating system to give the working set of the file system cache a higher priority for memory allocation than the working sets of applications. It will give the best performance on a file server that is not running other applications.
Programs: This choice is the recommended setting for machines running applications that are memory-intensive (SQL, Exchange, etc’). With this option chosen, the working set of applications will have a priority over the working set of the file system cache.
Memory paging occurs when memory resources required by the processes running on the server exceed the physical amount of memory installed. Windows uses virtual memory techniques that allow applications to address greater amounts of memory than what is physically available. This is achieved by setting aside a portion of disk for paging. This area, known as the paging file, is used by the operating system to page portions of physical memory contents to disk, freeing up physical memory to be used by applications that require it at a given time. The combination of the paging file and the physical memory installed in the server is known as virtual memory.
Physical memory can be accessed faster than the disk. Every time the operating system needs to move data between physical memory and the disk, there will be a significant system delay. While some degree of paging is normal on servers, excessive memory paging activity can effect the overall system performance. Thus, it is always desirable to minimize paging activity.
A pagefile can be created for each individual volume on a server, up to a maximum of 16
page files and a maximum 4 GB limit per pagefile. This allows for a maximum total pagefile size of 64 GB. The total of all pagefiles on all volumes is managed and used by the operating system as one large pagefile.
When a pagefile is split between smaller pagefiles on separate volumes as described above, when it needs to write to the pagefile, the virtual memory manager optimizes the workload by
selecting the least busy disk based on internal algorithms. This ensures best possible performance for a multiple-volume pagefile.
Optimal pagefile performance can be achieved by isolating pagefiles to dedicated physical drives on RAID-0 (striping) or RAID-1 (mirroring) arrays, or on single disk without RAID at all. By doing so, the PAGEFILE.SYS is the only file on the entire volume and there is no risk of fragmentation caused by other files or directories on the same volume. As with most disk-arrays, the more physical disks in the array, the better the performance.
Where pagefile optimization is critical, do not place the pagefile on the same physical drive as
the operating system, which happens to be the system default. If you don’t have a choice, put the pagefile on the same volume (typically C:) as the operating system. Putting it on another volume on the same physical drive will only increase disk seek time and reduce system performance.
To configure the PageFile, Open the System Control Panel, select the Advanced tab, in the Performance frame click Settings, go to the Advance tab, and within the Virtual Memory frame, click Change.
Best-practice tuning is to set the initial (minimum) and maximum size for the pagefile to the same value. This ensures that no processing resources are lost to the dynamic resizing of the pagefile. Setting the same minimum and maximum page file size values ensures that the paging area on a disk is one single, contiguous area, improving disk seek time.
The pagefile on all disks combined should be configured up to twice the physical memory for