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Hello this is a strange issue which we experience on some of our W2K8 servers. enter image description here

Why the heck is currently allocated just 16MB? Performance monitor says it is 99.9% used and out monitoring system creates alerts about this. On another server there was the same situation and once I set the paging file to "system managed size" it immediately expanded from 32MB to 16GB! Any idea why this happens?

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Vitas
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Taker a look at my answer at How do I tell if my Windows server is swapping? to understand why windows has a pagefile and not a swapfile like a unix system. The reason that system managed jumps up is because the system managed pagefile setting is intended to be large enough to hold a kernel-memory crash dump. It should be the size of your largest working set +1GB. As to why it's allocated so small- it's likely that you've simply never had to save many pages to disk.

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Jim B
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  • sorry, but this does not make much sense. If the pagefile is 99.99% used I think this is a good enough reason for OS to expand it no? Especially on a terminal server with like 35 users logged on. This server I am talking about now is another one and has only me logged in on now, but there are two processes with around 3GB working set... So I believe it is some kind of bug in PF management. – Vitas May 12 '15 at 12:27
  • No, the pagefile should only be expanded if you need additional virtual memory. You don't need empty pagefile space. – Jim B May 12 '15 at 17:46
  • One more time: doesn't a 99.99% pagefile usage mean that an additional virtual memory is needed? On other servers PF usage is 40 or 60 and such percentage. https://support.microsoft.com/en-us/kb/2860880 - "consider extending or adding a page file if all the following conditions are true:" – Vitas May 13 '15 at 06:15
  • I just changed the pagefile minimum size from 16 to 32. The effect was that perfmon immediatelly showed 90%PF usage but then in few minutes it slowly got back to 99%. But the currently allocated size still sticks to the minimum set size - D:\pagefile.sys has 32MB – Vitas May 13 '15 at 09:17
  • So think about that, you've got 12 GB of ram. How much of that would be pages that are not currently in use and could be preemptively written to disk? Chances are more than 32MB. To be clear the the pagefiel and virtual memory are only peripherally related- this is NOT unix and there is no swapfile- this is a memory mapped pagefile. To see this- delete the pagefile altogether then look in perfmon. Chances are after a short time you will see page faults- Where are those page faults going to (hint- what could be paged out to disk without a separate page file) – Jim B May 13 '15 at 22:50
  • Jim please why are you asking me this? Wasn't it my original concern that there should be much more then 16 or 32MB of pages to be written to disk? :) I don't get your last comment sorry. Which performance counter can suggest that the paging file size is not big enough? – Vitas May 18 '15 at 08:28
  • Ive edited my answer as the comment was too long – Jim B May 22 '15 at 16:16