Use Secure Virtual Memory - An observation

I recently noticed that my MacBook Pro, with a fresh install of Snow Leopard, had the item "Use Secure Virtual Memory" checked in the Security Preference Pane. A little research on these forums and I learned that was a new feature of Snow Leopard and it is on by default for portable computers and off by default for desktops.
The threads that I read in researching this touched on who needs this turned on and why as well as potential performance implications of having this turned on. The general message was that the load on the CPU would probably not be noticeable given the disparity between disk performance and CPU performance.
I had used my freshly rebuilt MBP with this option turned on for a couple of weeks when I noticed it and turned it off. While I'll agree that from a performance / response perspective I noticed no difference between it being on or off there was another measurement that did show a noticeable difference. I always run temperature monitor, including my CPU temperature, on my MBP, it ends up being sort of an early warning when something is beginning to make the CPU work harder than normal. Since turning off the "Use Secure Virtual Memory" option I can confidently say my typical CPU temperature has dropped between 6 and 9 degrees Fahrenheit for each working set of applications / activities that I do with my computer. So while there may not be a performance gain per se, clearly the CPU is working a little less with this option off.
Just wanted to share this for others to make an informed performance perspective decision on using this option.

It seems like the default for Mac Laptops is ON, while the default for Mac Desktops is OFF...

Similar Messages

  • "Use secure virtual memory" doesn't encrypt swapfile

    System: Fresh install 10.5 with full patches to 10.5.1 G4 iMac.
    No matter what I did with the "Use secure virtual memory" option in System Preferences, the -E switch did not get passed to dynamic_pager.
    Setting ENCRYPTSWAP=-YES- in /etc/hostconfig also had no effect.
    So I forced it in /System/Library/LaunchDaemons/com.apple.dynamic_pager.plist and verified that the -E switch is being passed to the dynamic_pager on startup. Guess what? The swapfile still appears to be in-the-clear.
    So I thought the contents of /var/vm/swapfile0 might be left over from a previous boot so I booted into single-user and ran +rm -P /var/vm/swapfile0+ then booted normally. Still appears to be in-the-clear:
    root# strings /var/vm/swapfile0 | grep -i password
    2/Applications/Utilities/Open Firmware Password.app
    */Applications/Utilities/Reset Password.app
    com.apple.openfirmwarepassword[
    com.apple.OpenFirmwarePassword
    Open Firmware Password
    open firmware password.app
    Contents/MacOS/Open Firmware Password
    com.apple.resetpassword
    com.apple.ResetPassword
    Reset Password
    reset password.app
    Contents/Resources/PasswordReset.icns
    Contents/MacOS/Reset Password
    root# ps -ax | grep dynamic_pager
    72 ?? 0:00.01 /sbin/dynamic_pager -E -F /private/var/vm/swapfile
    The technical term for this is "BAD."
    *Is encrypted swap a feature of Leopard or not?*
    I've seen discussions that this also applies to Leopard Server. I haven't looked at Tiger client or server yet.

    I was looking at this myself, more so because I was having performance issues and wanted to see if secure virtual memory was worth it. I encountered the same issues you had with the "Use secure virtual memory" checkbox. It seems that it isn't working. But then I spent like 5 minutes trying to understand the explanation in help:
    Use secure virtual memory: Select “Use secure virtual memory” to erase any information from random-access memory written to the hard disk by virtual memory.
    Keyword here is "erase" not necessarily "encrypt". This is my understanding of virtual memory. Let's say you have some application that uses a password. that application gets pushed to virtual memory. You access the application so it gets placed back in RAM. When this happens, and if you have secure virtual memory enabled, it will erase the information from the virtual memory. Without secure virtual memory that information still lingers in there till reboot and the swapfile is cleared. It's not necessarily encrypted though.
    Now, why when you specify the -E option and it doesn't encrypt the swapfile I'm not sure. the man page is rather vague, but does say that -E encrypts the swapfile.

  • Use Secure Virtual Memory leave on or turn off.

    My MBP came with the option turned on. But, since it raraly leaves my office, should I turn this off and would that gain me anything? Isn't it a security feature for if people have access to your machine or leave it somewhere it can get swiped?

    If someone gains access either physically or by somehow hacking into it, then they would probably begin looking for a way to find out the admin password. Encrypting the VM file both in memory as well as on the hard drive helps to prevent anyone from finding such information from the VM data.
    So actual true physical access isn't a requirement. Any access to the computer should be considered.

  • Use Secure Virtual Memory

    I know this has been asked before, my understanding is that this option is turned on by default in Apple laptops, but off in Apple Desktops.
    If you have a laptop that only stays "at home," is it necessary to leave on? Isn't this a security measure only if someone physically has access to your laptop (as compared to a phishing, email, or network breach)?

    If you're at home and the only main user then you don't really need it.

  • Secure Virtual Memory

    I understand what secure virtual memory does- it encrypts the swap file in OS X. Beyond that, what do I gain from enabling this security feature? If I don't encrypt my home folder with FileVault, do I really have a lot to gain by using secure virtual memory?

    Someone else may express a different opinion, but to me, if you don't have your files protected, there's little point in protecting virtual memory. The entire point of secure VM in my understanding is to prevent someone from gleaning information from the VM files that is otherwise unobtainable. If you haven't secured the files themselves, it's all wide open and no one will need to go to the trouble of examining VM. Only if you were to have files that you regularly erase via the Secure Erase that you want to be sure cannot thereafter be accessed at all, even in part, would secure VM seem to have any purpose.
    EDIT: Kappy's point about passwords, etc. is well taken, though reasonable physical precautions should be enough for most uses. If you have very sensitive logins, then secure VM may be worthwhile, though at that point FileVault, firmware passwords, and other precautions would also be advised (it's been shown that under some circumstances such information can even be recovered from RAM). It's all about what you need to secure, and under what circumstances someone might get access to your system.
    Message was edited by: Dave Sawyer

  • I activated secure virtual memory on snow leopard and now have lost everything

    Hi, wow I could use some help. I was curious and activated "secure virtual memory" in the security settings on my iMac 2.16 Ghz Intel core 2 duo and restarted. Now I can't access any of my files and the "users" folder won't open saying I don't have sufficient privileges even though I am not prompted for the administrator's password.  Every account seems to have reverted back to basic settings. When I try to open the finder I get a message saying:
    "The home folder for user "-------" isn't located in the usual place or can't be accessed. The home folder or Users folder may have been moved or deleted. If the home folder is located on the network, the server may be temporarily unavailable. If you continue to have problems, see your system administrator."
    I have backups on an external hard drive with time machine. How can I restore my computer?
    Any help would be greatly appreciated!
    Thanks!

    It appears I have resolved the issue on my own. I was able to change the permissions of the "Users" folder by right clicking and choosing "get info". I then was able to access the folder and saw that all of my information was still there. Whew!! And now that I've shut down and rebooted my desktop appears to be back to normal. I did hit the ? for information about the "secure virtual memory" option in security settings BEFORE I selected it and restarted, but the information about it was totally lacking so unfortunately this leads one to explore...

  • Filevault and Secure Virtual Memory

    If I have filevault enabled and secure virtual memory am I reducing my system performance because it would be encrypting already encrypted data?
    What sorts of security breaches can occur by not enabling secure virtual memory?
    P.S would this protect against the hack where a thief can extract my RAM and read my system password stored inside?
    Thanks
    -IP20

    Hi, Bob,
    Yes, you are right but "not exactly."
    If the computer is a laptop and is stolen with an intact battery and has not been shut down, then data in RAM may be accessible. It may be difficult, however, to take a desktop Mac without removing power which would cause the RAM's content to be lost (except for PRAM.)
    As for cryogenically freezing the computer that would most likely require removing the computer to another location. Removing frozen chips would be difficult if one wished to avoid having them increase to a temperature where the data would be lost.
    In any event I don't think the above are even relevant concerns for the consumer user. What would the typical home user have on a computer that would merit such extreme measures. Handling something cold enough to freeze RAM sufficiently to recover its content requires special equipment. I don't think my neighbor really cares that much - and the hacker would need direct access to the hardware. I don't think I would let someone have access to my computer that showed up at my door with a large thermos of liquid nitrogen! Furthermore who would leave their computer turned on and accessible, then walk away from it if they were so security conscious that they needed to use FileVault and Secure VM?

  • Securing virtual memory

    In 10.6 there was a setup for secure virtual memory that does not seem to exist in 10.7 (use to be in System Preferences>Security&Privacy).  Does this mean that virtual memory is automatically secured in Lion?

    190 GB is correct, and is not unusual. You are probably making the very common mistake of confusing Virtual Memory and Swap space (what you translated as "switch file"). They are not the same thing. Virtual memory is an abstract concept. It does not correspond to disk space or any other real resource.

  • Secure virtual memory just turned on

    I know when I first powered on my macbook, that pref pane had secure virtual memory turned off. I know I have not turned it on, but one of the recent updates must have just turned it on..
    anyone know which one??

    I have no idea. The performance hit however for having done this as a new default (?) is fairly negligible from what I can tell. I did exhaustive testing with XBench on both filevault, non-filevault, and secure/insecure virtual settings to see if there were major performance hits for using those options independently or in concert. Truth be told, the performance hit for secure virtual memory seemed to be fairly invisible (~1 % slowdown in memory tasks). That being said, Apple is probably wanting systems to be more secure out of the box, that's a good option to leave on by default IMHO.

  • Huge virtual memory use - 200GB

    I'm using a MacBook Pro (10.8.3), 2.4 GHz Intel Core 2 Duo, 4 GB. 
    When I look at activity monitor I see VM size at >240 GB!
    I only have firefox running.  When I reboot I see a similar VM size.
    I only have 20GB of free disk space. 
    While the system appears to be running ok, I'm troubled by the size of the VM memory - perhaps I have a virus?

    Winds Up!!!! wrote:
    When I look at activity monitor I see VM size at >240 GB!
    Not a problem.  From the Help: 
    VM size:
    VM size is the total amount of virtual memory space reserved by the OS X and your apps. The actual amount of virtual memory being used is likely to be much less, because OS X and apps frequently reserve virtual memory space that they don’t use.
    You may be thinking of swap space.  Also from the Help:
    Swap used:
    The amount of hard disk space currently being used as virtual memory
    Activity Monitor actually has pretty good Help.  See the Monitor your computer's resources section.
    I only have 20GB of free disk space.
    That's probably enough.

  • How to change Virtual Memory in Windows 7 with SSD and 16GB RAM

    I have SSD Samsung 850Pro with OS Windows 7 and have installed physical RAM 16GB.
    In Adobe Help/Optimize performance/Photoshop written :
    " To change Virtual Memory in Windows 7 and Vista, quit all applications and then do the following:
    Choose Start > Control Panel, and double-click System.
    Choose Advanced System Settings in the Tasks list.
    Select the Advanced tab and click Settings in the Performance section.
    Select the Advanced tab and click Change.
    Deselect Automatically Manage Paging File Size For All Drives.
    Click each hard disk letter to show the available space on that drive. Select a hard drive that has three times the amount of your computer’s installed RAM and doesn’t contain a scratch disk.
      Select Custom Size, and type the amount of your physical RAM plus 300 MB in the Initial Size box. Type three times the amount of your computer’s installed RAM into the Maximum Size box. 
    Click Set, and then click OK. Continue to click OK to exit all dialog boxes.
    Restart the computer: If you have applications open, select Restart Later, close your applications, then restart Windows. Otherwise, click Restart Now. "
    Select Custom Size, and type the amount of your physical RAM plus 300 MB in the Initial Size box. Type three times the amount of your computer’s installed RAM into the Maximum Size box.
    I have 16GB RAM
    in the Initial Size box : 16384+300=16684MB
    in the Maximum Size box:16684x3=50052MB
    but in the description of SSD written :
    " In order to address any potential lack of memory capacity, the Windows operating system automatically generates a block of virtual memory (pagefile.sys) on the C: drive.  For example, a Windows® 7 64-bit system with 4 GB of physical memory would generate 4 GB of virtual memory at boot time.
    In the past, before PC Memory (DRAM Modules) were available in high volume, PCs needed to utilize some HDD space to address any memory shortcomings. Today, with PCs featuring 4 GB of memory or more, it is possible to reduce or even eliminate the use of virtual memory.  Additionally, using expanded physical memory, rather than creating virtual memory on the SSD, has performance and reliability advantages for the entire system.  Some applications may require the use of virtual memory. In this case, please consider your specific application requirements before disabling this feature!!! ”..."SET virtual memory in the Initial Size Box :200MB and in the Maximum Size box: 2048MB"
    what is the right choice ???
    Please Help

    Windows set to default virtual memory : 16348 MB =16GB !
    But SSD program Samsung Magician wants virtual memory between in the Initial Size Box :200MB and in the Maximum Size box: 2048MB or 4096MB. If more than 8GB suggests that SSD will work slowly.
    Perhaps the description in Adobe execution Help / Optimize / Photoshop is not correct or ?

  • More hard-drives = faster Virtual Memory ? or not...

    2 internal HD's... only one is being used for Virtual Memory. If both were being used, it could double VM disk access - simultaneously uploading.
    I know that buying Crazy Expensive Mac Pro RAM would sort the problem out, but i ain't going to do that any time too soon. Besides i might get a new hard-drive... and 3 drives should be able to do VM noticably faster.
    does anybody know if i can set the second drive as a VM scratch disk also ?
    - or what part of mac os x controls these Virtual Memory and disks and if that can be tweaked
    - or are there any good little apps for controlling VM?
    Thanks peeps.
    nicholas.

    Thanks.
    I'm not going to do that, though it is certainly of interest. I had a thread on another board which went from "use a raid single" to "you cheepscate buy ram" too quickly for my liking.
    Of interest from that was :
    1) Not having ram is bad when it hits disk VM - that's the slow bit.
    1.1) so if you buy a little, that will raise the ceiling and you'll hit VM less often. Every titchy bit helps.
    2) if you never go beyond your ram - more ram is wasted.
    3) with some EXPERT tweaking performance can be gained from controlling where VM pages to - but really either buy ram or use less apps.
    4) the reason i brought it up was flight sim mode on google earth (apple alt a). Which is a waste of time anyway ! But that sometimes freezes and writes to disk for 5-10 seconds. My professional apps, are almost always in ram, so i think i'll forget it. Or buy ram.
    5) if you want to know if you need ram - look at activity monitor - but combine "free AND inactive" to see how much/little is spare. Also read the "vm page ins".. if there are lots (7,000 in 10 minutes) you're into slow VM land.
    really... it's only apparent because the mac pro is lightning fast most of the time, and WHEN you're waiting on the HD - even though it's still running really fast - it is more apparent.
    Thanks everyone. Happy Mac'in.

  • Insufficient Virtual Memory to open Photoshop 6.0.  What to do?

    Hello,
    I use PhotoShop 6.0.
    Suddenly I can't open the program. Instead I get a message to the effect that the Volume that Windows is using for virtual memory isn't sufficiently large. Every other program works fine. No viruses or other problems. I have hundreds of spare gigabytes of memory. I've tried reinstalling the program. I can open ImageReady. Got me stumped.
    Any thoughts would be greatly appreciated.
    Thanks,
    --Dave

    first try resetting the preferences per the instructions in the faq.
    that'll reset the scratch drive too. make sure you really do have enough free space. (several hundred gig ought to cut it! :) )

  • How many virtual memory do you have on 10.6.1

    Hi everybody,
    a few time ago, i was on 10.5.7 on a Macbook unibody 2Ghz 2Go RAM, so, there, my MV (virtual memory) Was about 7,45Go with lot of apps running in background...
    now, on Snow Leopard my VM is about 130Go without anything running?
    is it normal? my other Mac (last Macbook pro 13") has the same VM than my MacBook 2Ghz...
    so what is your VM? is it normal??? link with the 64bit?
    130 is also the same than my hardisk? 160Go
    so many questions tha make me esitate to downgrade on 10.5.8...
    tks answering

    My Mac Pro also reports about 130GB for VM size (in Activity Monitor).
    In spite of, or perhaps more clearly than what the Activity Monitor helps says - that is - "Virtual memory, or VM, is hard disk space that can be used as memory".
    It is the potential size that might be used on disk.
    I look at my actual swap file (located in /private/var/vm) and it is only 64 MB.
    Further in my case according to Activity Monitor none of that space is being used as reported in "Swap Used"
    I believe the big increase you see is due the move of most system components to 64 bit and their potential to use more virtual memory.
    I suspect you will find similar figures for the swap file and a modest usage of it.
    I wouldn't worry.
    Steve

  • Mac OS X hard disk memory discrepancies, virtual memory culprit?

    Recently my iMac (2.4 ghz intel core 2 duo, 4 GB ram, 320 GB HD running Snow Leopard 10.6.5 ) has started acting really weird. Mainly, the hard drive space has reached almost zero for no apparent reason. I've added up the volumes of the four files on my drive (Applications, Users, Library, and System) and come up with a sum of only 123.94 GB taken up. I've also scanned my drive using OmniDiskSweeper and Disk Inventory X (the two programs recommended to me via colleagues and tech support) and came up with a similar result (give or take a gigabyte). Eventually i checked the Activity monitor, and found to my surprise that a whopping ~135 GB was being used for virtual memory purposes. The virtual memory usage was read right after startup with no background programs running. Currently my drive only has 4 to 5 GB of free space on it, and that's after deleting certain unnecessary programs and files. i've tried rebooting my mac several times, but to no avail, and the trash bin is empty. I don't even have space on my hard disk to burn a DVD through iDVD anymore, and i need that capability for my job. Is virtual memory the culprit behind these problems? What can i do to fix this?

    Eventually i checked the Activity monitor, and found to my surprise that a whopping ~135 GB was being used for virtual memory purposes.
    This is misleading.
    Is virtual memory the culprit behind these problems?
    No. The actual problem is most likely excessively large items in /private/var/log/ and/or /Volumes/; the Finder's Go to Folder command can be used to navigate to both. You may also want to check the actual VM swap space in /private/var/vm/, but shouldn't delete anything in there.
    (55251)

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