Corrupted disk drive image, Parallels didnt flush

[dm3]

I ran into a serious problem with build 3094. I had installed a new application on Windows 2000 within Parallels, had used the new application for several minutes. I went to do something unrelated in Mac OS X which resulted in a system hang. (iTunes was attempting to access a network drive which was no longer available).

End result, the system hung, I had to do a hard poweroff. I had not used the Windows 2k parallels session for several minutes, plenty of time for it to sync up with the hard drive.

When rebooting, my Windows 2000 disk image was severely corrupted so that I could no longer boot Windows 2000. I had completely lost my disk image.

Parallels should have written sync up the VM image to the harddrive rather than keep so much in memory.

Luckily I had a recent backup of the disk image.

 

[joem]

This is where we probably need some experimental evidence or some comment from the developers.

What is the write cache policy? Does Windows flush to Parallels? How soon? Once Windows writes, what is Parallels cache policy? What is OSX cache policy for Parallels.

Windows 2k has a lazy writer that can take some time to do disk writes, but what happens from there? Once Parallels does its writes, how long does it take for OSX to write to the physical disk?

Does the adjustable Parallels cache policy affect write policy?

Interesting questions, no?

 

[Liong612]

That happened to me too

I installed a big program on my Windows 2000... what i mean is that complete Visual Studio, plus MSDN. A few minutes later i was forced to restart VM, and then i could not boot back to windows 2000 due to files were corrupted.
I lost everything and had to re-install windows 2000 from scratch. I learn my lesson. Next time i will back up first.

 

[rhind]

What is the write cache policy? Does Windows flush to Parallels? How soon? Once Windows writes, what is Parallels cache policy? What is OSX cache policy for Parallels.

Does the adjustable Parallels cache policy affect write policy?

Interesting questions, no?

I've been guessing that it does because if I set the cache policy to be for the VM, I get much better response from the VM that OS X and a lot less disk thrashing when in Parallels, but switching back to a native app leads to disk thrashing.

I have it switched to the other way round (optimised for OS X) in the hope that the .hdd image isn't cached at all by OS X so when windows thinks its written to disk, it has to hope reduce the chance of corruption (I have had a few cases in OS X recently where I've had to kill power to my laptop).

You can disable write caching in windows for the drive also if you go to the properties of the drive from Device Manager and look on the policies tab. I usually run with all caching disabled to help reduce the issue of drive corruption (even when running WIndows on a PC).

But I agree, it would be good to have confirmation from Parallels developers on what the 'cache policy' option actually does.

Cheers

Russell