Windows memory limitations - it can't be coincidence

Discussion in 'Installation and Configuration' started by bob.ritter@greshamsavage., May 22, 2008.

  1. I've been watching the threads about memory limitations in windows, and specifically about those who were once able to allocate a full 2048 MB of RAM to a WIndows VM, but suddenly began receiving "Parallels Desktop failed to allocate the specified amount of memory..." error messages. The only "fix" was to bring the allocated memory down to 1024 MB or less.

    Most of the messages seemed to blame the problem on one or more of the recent OS X updates. Although I had regularly applied all of the posted OS X updates, I had not experienced the problem, and was quite happily running WinXP VMs with 2048 MB of RAM on both my MacPro and my MacBookPro.

    Until, that is, I replaced my system disks with larger drives.

    The MacPro was first. I replaced a 750G system disk with a 1T disk by first cloning the old drive to the new. The first time I attempted to run a WinXP VM I received the dreaded error message. Booting from the old disk eliminated the error message and allowed running at the full 2048 MB memory allocation. The only difference was the size of the disk.

    Since my use of Windows on the MacPro was really limited to fairly low intensity stuff, I didn't sweat it. I did upgrade to build 5600, thinking that was going to solve the problem, but found no difference.

    A few weeks later, however, I discovered the availability of a 500G drive that would work in my MacBookPro. Of course, I had to have it. When I installed the new drive (same process - clone the old 250G drive to the new 500G drive, then replace the drive), the same result occurred. The 2048 MB WinXP VM that had been happily running on the laptop also failed with "the failed to allocate" error message unless the memory allocation was reduced to 1024 MB. Here, too, booting from the old drive, identical except for size, allowed allocation of the full 2048 MB, but not the larger HD.

    In each case nothing changed except for the increased size of the HD.

    I have difficulty believing that this is coincidence.

    My next step will be to clone the large drive to the small one and make sure that the larger memory allocation still works, but that won't be for a few days when I have more time.

    Any thoughts???

    thanks...Bob
     
  2. Jay Levitt

    Jay Levitt

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    That fits with my experience, too - although I was changing a whole bunch of things at the same time, so I can't be sure.

    It'd be interesting to see if it's the *system* volume that matters, or the volume where the VM is stored, or some other volume. If it's not the system volume, a workaround could be to move the VM to a smaller partition...
     
  3. John@Parallels

    John@Parallels

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    6,343
    2 GB limit is Mac OS limit for user space processes, when you have some processes running, sometime Mac OS cannot allocate 2 gb , because other processes are not allocating memory in continues address space.
    Please do not forget that officially Parallels Desktop Supports 1500 mb memory for VM.
     
  4. K-Dee

    K-Dee Bit Poster

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    The funny thing is, I have a Vista VM that used to work with 2GB until I cloned my disk (because I was adding a bigger one). In fact the original disk still runs fine with 2GB if I boot off of that one. The clone doesn't work with anything more than 1GB. So the clone did something to PD, or PD has a bug that's somehow related to cloning of disks.
     
  5. John@Parallels

    John@Parallels

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    6,343
    I suggest you to create new Virtual Machine and attach existing disk there.
    Parallels Desktop for Mac user guide on pages 58-62
    to add existing disk, please stop Virtual Machine and add new disk
    Parallels Desktop for Mac user guide on pages 191-193
     
  6. K-Dee

    K-Dee Bit Poster

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    53
    Been there. Done that. Doesn't work. It still gives the memory allocation error.
     
  7. K-Dee

    K-Dee Bit Poster

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    53
  8. Jay Levitt

    Jay Levitt

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    Ditto! I just upped my XP VM from 1024 to 2048, and it started up without even rebooting the Mac.

    K-Dee: Nice find!

    John@Parallels: I can't thank you enough for your helpful comments in this thread.
     
  9. John@Parallels

    John@Parallels

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    6,343
    I hoped so, that 10.5.3 will solve user land memory space allocations problem.
    Glad to hear that problem is resolved.
     
  10. Portable2

    Portable2

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    Ditto! I just upped my XP VM from 1024 to 2048, and it started up without even rebooting the Mac.

    K-Dee: Nice find!

    John@Parallels: I can't thank you enough for your helpful comments in this thread.


    Nice find K-Dee!! I did the same thing, upgraded my Mac HD from 160GB -> 320GB and Parallels wouldn't start the VM when the memory was over 1GB. I reapplied 10.5.4, rebooted and solved the problem!

    Thanks!!

    Adam
     

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