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I am using VMware on a laptop computer, which is truecrypted as a theft precaution. The VHDs are ceated as single growable files (i.e. not split in 2 GB chunks, no preallocation of whole VHD space.) Host: Windows7 64bit. Guests: Windows7 32bit and WindowsXP 32bit. VMware version: VMware player 4.0.x.


When using the VMs extensively, I often experience painful minutes of 100% I/O activity on the host HD. This of course slows everything down. According to "Perfmon /res", the culpable host processes are system and "vmware-vmx.exe", ("system" consuming the lion share). There is big read AND write traffic, regardless of what I did in the VMs. The problem seems to be worse with Windows7 guests that with WindowsXP clients.

Excluded causes: Perfmon confirms that there is enough real RAM. The antivirus on the host is configured to skip all file types which occur in the VM folders.


Are there any Truecrypt operations affecting the whole VHD file on the host, when I made a write-access to a small portion of the VHD from within the VM? Would it therefore help to split the VHD files into 2 GB chunks?

Or is this a stupid thought because the Truecrypt ciphertext block size is just 16 bytes?

Any other idea out there?

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You can safely presume that TrueCrypt has linear performance footprint because full disk encryption is implemented as a block-level driver.

VMware, on the other hand, is slow with dynamic volumes. I have seen similar effects with and without TC. So a possible solution would be to use fixed VHDs.

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