I also have that idea for a while and together with Michael Lucas-Smith 
we started to work on something like that on VisualWorks, it's called 
Prevayler and on my wiki you can find more about it:

	http://wiki.eranova.si/aida/Prevayler+persistency

I think that a Prevayler is quite easily achievable especially on 
VisualWorks, because it supports so called object immutability, that is, 
you can set an object read-only and when someone try to change it, an 
UHE is raised. All a Prevayler needs is to catch that exception and save 
changes.

I don't know if Sqeak supports immutability too?

Janko


Bert Freudenberg wrote:
> Am 23.10.2006 um 21:30 schrieb Philippe Marschall:
> 
>> 2006/10/23, Cees de Groot <cdegroot at gmail.com>:
>>> On 10/23/06, Philippe Marschall <philippe.marschall at gmail.com> wrote:
>>> > > > So about 300 Euros?
>>>
>>> [...]
>>>
>>> > 64bit VM?
>>> >
>>> You pay the hosting bills for a new box? ;)
>>
>> I'm willing to pay 2 GB of RAM if that's what is needed to run Pier.
>> That Squeak can't handle this is a Squeak specific limitation that has
>> nothing to do with the point that memory is that cheap.
>> As pointed out numerous times on squeak-dev and disputed by none, all
>> VM related issues can be fixed easily by just fixing the VM. This is
>> no problem since the VM is open source.
> 
> If we had a transactional virtual object memory that's continuously 
> saved to disk (think OOZE/LOOM), that might be viable. Perhaps with 
> Magma you could have almost the same semantics, just be careful what you 
> touch. But not with the current object memory. No way. Not if you care 
> about the data.
> 
> It's not about RAM being cheap or not. It's about designing for the 
> common and the worst case. Why you would want to bring in gigabytes of 
> data if the working set is just a few megabytes is beyond me.
> 
> - Bert -