Re: [Qemu-devel] What is the minimal linux setup for running Qemu ?

[Richard Neill]

jeebs wrote:
> From: "Richard Neill" <address@hidden>
>
> > Lastly, have you checked out Metropipe's product? This (free) package 
> > from:  http://www.metropipe.net/ProductsPVPM.shtml
> > contains:
> > All that is needed to run Qemu under Linux
> > All that is needed to run Qemu under Windows
> > A Linux Guest system.
> > And it fits on a USB key.
>
>
> Thanks for telling us about this...  Nothing inovative, but nice to know.
>
> However, I'm not so sure I'd want to run it on a flash memory device!

Actually, the metropipe key doesn't have this problem. The Guest OS is 
Damnn Small Linux, which is knoppix-based. This is simply an iso CD-ROM 
(image) which is read-only. So the only writes are to your 
home-directory. I haven't tested it, but I'd assume that the memory key 
home directory is mounted sync,noatime.

Metropipe's product is actually quite interesting, since they aim to 
store all your files on their server, and the memory key provides 
firefox,ssh etc and a virtual private network.

> Any virtual disk is going to do quite a few writes, and flash memory can only 
> do so many before it starts to fail.

I thought this number was > 100,000   - so it's still not really an 
issue except for atime and swap.

> It's worse with an OS that does a swap file (such as BartPE (WinXP) or Win9x on 
> a flash device), but even for a non booting drive, the directory structure 
> could still go through a lot of writes.  (Especially if the OS modifies the 
> 'file accessed' time for a file that gets accessed often.)
>
> Sure, flash memory can do many writes, but it only takes a single bit to fail 
> to cause problems and possibly make it impossible to get important stuff off 
> that virtual disk.  And directory structures are prime candidates for failing 
> first.


Not relevant here, but doesn't JFFS deal with this problem?

> It would have been better if they had done something to set up a small ram disk 
> to hold things, and then copy it back to the device when you get done.



Regards

Richard