RE: [Xen-users] Xen on USB Key

["Petersson, Mats" <mats.petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Henning Sprang
> Sent: 23 January 2006 12:31
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] Xen on USB Key
> 
> On Mon, 2006-01-23 at 12:17 +0000, William Man wrote:
> > I had initial thoughts along the same line.  I have built 
> the kernel 
> > to run off a key, but not tried it yet.
> > But ALL logging need to be moved to tmp, all lock files need to be 
> > moved to tmp, etc...
> > 
> 
> I heard of people building usb-bootable version of some 
> (live)distributions, and that they had to deal with similar issues.
> Maybe it's worth looking at them how they solve this issue. 
> Sorry for not having a link at hand, I just remember 
> something like that.
> 
> 
> > As the general lifetime of a key is like 10yrs, if you only 
> write on 
> > it once/twice a day.  But if you use it daily then..... it 
> won't last long.
> > 
> 
> What is "not long"?
> If it's only a month, that's probably enough! That's a cool 
> tool, if you use it daily, spending 20Dollars/Euros each 
> month for a new USB stick is not exactly a lot compared the 
> usefullness of that tool.
> 
> The same technology could probably applied to 2.5" usb 
> harddisk, making it slightly bigger, but still possible to 
> have your complete desktop in a shirt's pocket.
> 
> Henning
> 
A flash device will allow writing to the same block (sector) at least
100000 times, AMD/Spansion devices support 1000000 writes to the same
block. A write, in this case, is defined as a complete cycle of erase
(make it all ones) and program to zeros. 

If you do a write every second (to the same place), one million seconds
is about 11 days (277 hours), but it's very unlikely that a clever Flash
File-system would allow you to write to the same area over and over
again, as it's normally remapping sectors when they are written, rather
than doing a erase/write cycle, so it should last a lot longer than
that. [Caching in the OS will also help if you're writing to the same
place]. 

--
Mats


_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users