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

[jeebs]

From: "Richard Neill" <address@hidden>

> 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 

Right.

> home-directory. I haven't tested it, but I'd assume that the memory key 
> home directory is mounted sync,noatime.

I don't happen to have a memory stick to test it with.  (To be honest, I've 
never gotten around to buying one.)
 
> 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.

There's nothing on the web site about that.

Their VPM page talks about storing things 'in your pocket' etc., so it sounds 
like just a typical local virtual drive right on the memory device itself.  
That's what prompted to me make my comment in here.

They do provide a demo of their tunneler, but I don't see anything about the 
product requiring its use etc. etc.
 
>> 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.

I really don't know what the cycle count is.

Certainly on the higher quality flash chips, it's over a million bit write 
cycles.

But with so many ultra cheap memory sticks with memory from no telling where, 
it's not something I'd want to depend on for more than a few tens of thousand 
writes per bit.

And unless there is proof to the contrary about the OS and the apps, you kind 
of have to assume that anytime you actually run any programs, it's going to 
update a directory or a config file, or whatever.

Maybe I'm wrong, but at this point, I find it hard to believe that it's not 
going to be doing lots of writes to the virtual disk when you actually use 
stuff, like MetroPipe is trying to suggest.   Simply booting it for a 
demonstration or the ocasional emergency, etc. is no problem.

But MetroPipe is talking about actually using it for real, and I'm real 
hesitant about the life span of the flash area where the directories are at.  
Unless MetroPipe has taken explicit steps to reduce this and I don't know about 
it.


There isn't enough information of the web site to say for sure how it's set up 
(I haven't tried it yet), but I'd guess it's nothing more than a typical 
virtual disk for storage of your stuff, and an ISO for the linux.

Just a simple, no frills setup involving qemu, an empty virtual disk, and a 
standard DSL iso image.  That's why I said it was interesting, but not 
inovative.  (If I'm wrong, then great!)



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

Don't know.