Review firewall settings such
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If ever your Windows 2003 server is running slowly, then the first place to look for a bottleneck
is memory. Another way of looking at server performance, is that machines with
plenty of RAM rarely give problems. A bonus of plenty of memory is,
that to a degree, abundant RAM compensates for
strain on other resources.
On old servers, lack of memory would give you the full sensory input, you could hear the disk paging, see the light flashing, and 'Mad' Mick swears you could smell the disk thrashing. Even with these
sensory clues, it is still worth while monitoring memory with Performance Logs. Please also remember the big picture. So once you have had a quick look at memory, remember to check the processor and
disk counters.
The servers most likely to suffer from memory shortage are pure database servers
for example, Oracle or SQL. Email servers also require plenty of RAM.
Pure domain controllers are less likely to experience memory problems.
The more available memory the faster the server can respond. When I check a server's memory with performance monitor, the first
counter that I add to the log is Memory\Available bytes. As long as the trace
indicates more than 10MB of free memory, then I conclude that the server has
sufficient RAM.
Diagram 1 shows a white descending line,
and the legend confirms
that Available bytes are down to 3MB. Clearly this machine needs more memory.
Suppose a spreadsheet wants to start a new thread or a database needs to
sort data, what each needs is memory. The operating system
provides this memory at
least 100 times faster using RAM, than it could using a disk based pagefile. This is why a
large pool of free memory is so important to an application server.
Take care to distinguish between these two paging counters: 1) Pages
/sec (Hard page faults) 2) Page Faults /sec counter is likely to be at
least twice the value of the above.
Two problems with monitoring in general, firstly no counter should
be taken in isolation, secondly spikes should be ignored, or at least played
down.
The less paging the better your server's performance. Most authorities
agree that Memory: Pages / sec is a key memory counter. This counter
measures 'hard' page faults, in other words the page in nowhere in memory,
so the VMM (Virtual Memory Manager) has to fetch the data from the pagefile
on the disk; in computing terms that takes an age.
I am reluctant to disagree with other authorities, but from my experience,
I would put the threshold as high as 20 pages /sec, before blaming paging as
the bottleneck. Moreover, I
would not trust pages /sec as an indicator of a bottleneck without confirmation from low Available bytes.
(see above)
In truth, if you put 5 experts in the same room, they could all spot a
memory bottleneck, but when they wrote up their notes, they would use
different time slices and different thresholds, consequently, it would seem that there
was a conflict where none actually existed.
2) Memory: Page Faults / Sec
Page faults / sec is the sum of hard and soft page faults. Soft page faults are
where the data is found elsewhere in RAM. For example, Word has opened
the spellchecker, and now Outlook wishes to use it, there is no need for
another
call to the disk as the spellchecker is already in memory.
While the pagefile is less likely to be a bottleneck it is easy to check, and
satisfying to fix. You could also confirm that it is on the most suitable
disk, and if possible split the pagefile over two disks and thus improve access
times. (Note the object here is Page File not Memory)
Because the changes are so gradual, you are better off using this Page File % Usage counter
as an alert, rather than a log. I suggest setting an alert
on a limit of over 70.
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resource overload.
Perhaps the NPM's best feature is the way it suggests solutions to network
problems. Its second best feature is the ability to monitor the health of individual VMware
virtual machines. If you are interested in troubleshooting, and creating network maps, then I recommend that you
give this Network Performance Monitor a try.
If you really want to see a memory bottleneck that you can measure with
performance monitor, then add the MAXMEM switch
to your server's boot.ini. For example:
multi(0)disk(0)rdisk(0)partition(1)\Windows="Windows Server 2003" /MAXMEM=256
Thanks to better programming, the problem of applications leaking memory is
slowly disappearing. Programs need memory - fair enough, but when they
close, if they fail to release
the memory back to the pool - not fair.
Monitoring the slow build-up in the non-paged pool is a
classic job for an alert. You are unlikely notice much creep in a day's
logging, but over a month you could have lost a significant amount of memory.
If you are in a hurry or just plain ruthless, a reboot solves memory leakage
into the non-paged pool.
Memory: Cache Bytes
With Memory: Cache Bytes, you have the choice of monitoring the total
or breaking down the cache into four categories.
Note Memory: Cache Bytes = Total of these four individual counters
Data Map Hits is the percentage of data maps in the cache that
could be resolved without having to call the disk. It is a measure of how
many data
pages are already in physical memory. (Note the object is Cache not Memory
like the others.)
Committed Bytes
If the value for committed bytes is greater than physical memory, then more
RAM would help.
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The best feature of this new this new version of SolarWinds VM Monitor is that it
checks Windows Hyper-V. Naturally, it still works with virtual machines on VMware ESX Servers. VM Monitor is a
clever
desktop tool that not only tests that your server is online, but also
displays the CPU and memory utilization for each node.
It's easy to install and to configure this virtual machine monitor, all
you need the host server's IP address or hostname and the logon info. Give
this virtual machine monitor a try - it's free.
Your goal is to discover which application (process) is using most of the memory.
Either quickly check the Processes tab of Task Manger or better, create a log
of the processes with performance monitor. Developers could consider
investigating other tools such as PViewer from the Resource Kit.
Many applications have their own settings for configuring memory usage.
It is not that they can magically produce more memory but they
can make the most of the memory the server has. Programs like SQL or
Exchange have settings to control their caches. The key question
is: should the memory
be tied up in a file cache or would it better
used by the application's owncache? I favour the latter. So
adjust the applications cache
or
memory settings, and then see what effect your changes have by logging with System Monitor.
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There are so many good gadgets; it's like having free rein of a
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Not enough available memory? The easiest cure for memory problems is to
open up the server and add another stick of RAM. Salesmen always
seem particularly helpful and knowledgeable on the best type of RAM for my
server.
I have a suggestion for future purchases - Always buy machines with more RAM
than you need now.
Virtual Memory Settings - Pagefile
Perhaps I should have started by suggesting that you check the
performance of the pagefile,
particularly as it may offer a cost-nothing solution to memory problems.
The 'Old Trick' is to move the paging file away from the operating
system's partition, and if possible, create a paging file on a separate
disk. Opinion's vary about the size of the paging file relative to the
amount of RAM, but x2 is a good rule of thumb.
To check or set Virtual Memory follow this path: Control Panel, System
Properties, Advanced, Performance and Advanced.
Beware: While you are at the menu, see screenshot,
beware of the 'No paging file' radio button, other than test I cannot think
of any reason why you need to set the radio button next to this setting.
Another Pagefile Trap: If you don't have any pagefile on
the system partition then you lose the ability to debug Stop errors.
That said, debugging is a tricky business, and one that I have had little
success. If the main Stop error code that you see when the screen goes
blue does not help to solve the problem, then in my experience the detail in
the memory dump is just too hard for ordinary techies to interpret.
Performance Monitoring with PowerShell
PowerShell has a cmdlet called Get-Counter, which provides an alternative
technique to employing Perfmon for investigating computer memory usage.
See more about
Get-Counter.
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Learn the secrets of which
counters to monitor. Master performance monitor logging,
develop your skills with structured exercises and examples. Print
out a copy to read, while you design logs and alerts to detect network
bottlenecks.
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SolarWinds' performance monitor is designed for detecting network outages,
making it easy to see what's working, and what needs your attention.
This utility guides you through creating network maps; it also helps
identifying whether the
root cause is faulty equipment, or resource overload. Give NPM a try.
