Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a Windows Vista inside a VMWare workstation virtual machine, which I need to boot as fast as possible (for testing certain software).

I can commit about 4GB of RAM for cache, which, in theory, can make Vista boot mostly from RAM. While the filesystem image is 40GB, I doubt more than 4GB is accessed during boot.

So I need to:

  1. Disable all synching, enable write caching, so all writes go into cache and flushed to disk only asynchroniously (I don't care about integrity, this is a throw-away testing image).

  2. "Force" host OS to commit certain amount of memory for caching that one specific file (VMWare image). Currently, host OS is Windows 7, however I'm open to all suggestions. I thought about making iSCSI target on Linux and then booting VMWare from it, but I don't know how to enable such "file-specific" caching in Linux either.

How can I do this?

Notes: I don't care about data integrity, don't care about performance after boot. I realize that adding RAID0 with several SSD disks solves my problem neatly, but I need quick-n-dirty solution now, without adding expensive hardware.

share|improve this question
VMWare supports composite images, i.e., a base file plus a difference file. If you could put the content you wanted cached into one of the two files, you could put that entire file into a RAMdisk. Unfortunately I don't see any reasonable way of dividing the content. – Harry Johnston Feb 15 '12 at 0:45
Alternatively, you could investigate ReadyBoost, the mechanism in Vista for caching boot content to fast media. It might be possible to create a 4GB virtual disk drive and convince Vista to use it for ReadyBoost, then put the corresponding image file on RAMdisk. – Harry Johnston Feb 15 '12 at 0:48

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.