"Virtual memory " what kind of memory ?

Question

tell me more about virtual memory and how it works? any virus can attack on virtual memory?

Answer 1

when all of your RAM(Random Access Memory) gets used up, windows uses some part of your hard disk as RAM, this is called virtual memory, viruses cannot attack virtual memory but they surely can reside in there, most anti viruses do a memory scan before scanning the hard disks, these type of anti viruses deal with this problem. NOD32 is one of them

Answer 2

Virtual memory is just like that. It is virtual which is created by windows as a temporary memory and gets deleted when the computer is restarted. Though virus can not directly attach Virtual memory however, it can attack the underlying hard drive on which the page file is created.

Answer 3

Here is what happening when you have a warning sign showing " virtual memory is low warning". Your computer uses physical memory, aka RAM, and virtual memory. Virtual memory is used to simulate more RAM when your computer is reaching its maximum CPU and RAM usage. It very similar to a bucket filling up with water. If your CPU needs water you can bring this resources to it. But your bucket size is limited. The more programs you use and disk space the more water is needed. But you can only deliver the set amount of water because your bucket size is limited. The bucket is your RAM. However, you can use a spare bucket to quickly to help meet the demand. The virtual memory is that spare bucket.



You can change your virtual memory by altering amount of free resources for your computer to use for it, in a sense making the spare bucket bigger. Virtual memory uses free space as a resource. So you can change the the amount free space reserved for the Virtual memory.



When you get to the Virtual Memory menu select the Custom Size check box. Then choose the initial size and the max size. Depending on how much free space you have you can choose what that amount of free space you want. If you are still confused the link below has a visual step by step instructions.



1.Click Start, and then click Control Panel.

2.Click Performance and Maintenance, and then click System.

3.On the Advanced tab, under Performance, click Settings.

4.Under Virtual memory, click Change.

5.Under Drive [Volume Label], click the drive that contains the paging file that you want to change. In most computers its C:

6.Under Paging file size for selected drive, click to Custom size check box. You can enter the amount of memory you would like to reserve for Virtual memory by entering the initial and maximum size.

7.Click Set



Hot tip: Keep the initial and maximum size the same to cut down on your CPU access. This will stop your CPU from constantly change your Virtual memory paging size. Also set the size 1.5 times higher than your physical memory.



Hope this helps!

http://www.delete-computer-history.com/increase-virtual-memory.html

Answer 4

When ever any program, including a virus, is 'run' on a computer, that program is picked up from it's storage location on the hard drive and is loaded into memory, where it proceeds to give instructions and get information from the hardware and other software and that is what makes your computer work. Very few things actually run from a hard drive, a hard drive is just storage that the memory can access to get the programs it needs to run the computer.



The two main types of memory that your computer uses (we won't get into processor cache) are physical RAM and virtual RAM. Physical RAM is the memory that's on a 'stick' with chips on it plugged into your motherboard, it is completely electronic and has no moving parts. This is used for loading and running programs mostly, but when it gets full we can't just not run something, that programming needs to keep running so it's 'paged out' or 'swapped' to virtual memory.



Virtual memory is kept in a file on your hard drive that's totally dedicated to acting like RAM. This file is called a 'page file' or 'swap file'. When the real RAM gets loaded as far as it can go, Windows and other systems use this file as an overflow for things that for one reason or another must remain loaded into memory.



The computer actually sees this memory as being the same as the physical RAM, the main difference is that because it's on a mechanical drive and not a solid state electronic component it's a LOT slower. There are various tricks to speed it up somewhat, but the easiest is to just add more physical RAM so that fewer critical functions get sent to the virtual RAM page file. Windows will automatically use the physical RAM for high speed operations as much as possible, then fall back to the lower speed virtual RAM on the page file on the hard drive. It will also clear things that aren't being run at that exact moment to the page file for easy access when needed and to create more room for things that are running right at that second. Even on a system with a lot of physical RAM, this process is constantly occurring but the page file (virtual memory) is accessed a lot less because it's not needed as often. That's why your computer runs faster with more physical RAM installed.



Where virus activity in the page file or virtual memory occurs is not because a virus specifically attacked the page file but because the virus was loaded into memory (it was 'run') in the first place. Often a virus will then swap itself out to virtual memory after it loads. This is why the first thing that any anti-virus program scans is memory, both physical and virtual.



The thing about virtual memory is that it's 'persistent', that page file stays on the hard drive when the computer is shut down and powered off. The physical RAM is 'volatile', when the power goes off whatever is in the chip is gone forever, it's called volatile because it's like it evaporates into nowhere. So IF a virus is still in the page file in virtual memory it can load itself when the computer starts again.



Any decent anti-virus software will catch that though, so you don't need to be concerned about it unless you don't have an anti-virus product installed, updated, and running on your computer. Virus writers LOVE people that don't think they need anti-virus software, if it wasn't for them there would be almost no virus problem.



If you're running Vista and you only have one Volume (which is a disk or a RAID array that appears as a drive letter like "C:\") then don't mess with the page file or change the virtual memory settings. You'll only slow down your system, Vista is the first Windows Operating System that actually does a very good job of handling virtual memory.



Since XP was released it's not a good idea to change the virtual memory settings to a single size that's 1.5 times the physical RAM, that's WHY you can get a "Virtual Memory Low" warning. You'll never get that warning if you don't tamper with the virtual memory settings as XP will add room to the page file automatically. XP won't expand and contract the page file, unless disk space becomes low it will just leave the page file at the largest size that has been needed so far. Setting the page file to a constant size is a very OLD trick from the days of Windows 98, NT, and 2000 that was used to get a very small gain in system performance.



Having said that, one thing that you can do is to move the page file off of the root volume, usually that's "C:\", IF you have more hard drives available to move it to. That way the Operating System can be accessing files on the System Volume (C:\) at the exact same time that it's using the page file. For instance, the computer I'm writing this on has 7 internal hard drives, so I've moved the page file to H:\ from C:\. You have to know your equipment though because moving the page file to another volume on the same hard drive will do no good at all. This computer also has a 4 GB flash drive for ReadyBoost and 8 GB of physical RAM so all it needs a page file for is to do a memory dump so I can run debugging tools in case of a system crash. With ReadyBoost and that much physical RAM the computer never uses much virtual memory.



I hope that answers your questions about virtual memory and virus activity.



Good luck and happy computing.



**Note to computer geeks** I know the difference between saving inactive virtual memory pages and segment swapping and the corresponding page vs. swap file nomenclature, that DMA and permanently resident pages also use physical memory, etc. I'm trying to make this easy to understand and informative and you don't need to be worried about the technical accuracy of the answer, get over it.

Answer 5

it means your page file. windows uses it instead of physical RAM when it can. a virus can't attack or damage your physical RAM but might change the size of your page file.