File-level copy-on-write?

File-level copy-on-write?

[Roland Paterson-Jones]

Hi

I have an application where I want to make relatively frequent copies of 
a large file, and the copies will remain largely similar to the original.

It seems to me that a file-level copy-on-write would support this well.

So, does reiserfs support anything like this?

If not, can I implement this easily (how easily ;) ) with a plugin.

Any ideas and pointers greatfully received
Thanks
Roland

Re: File-level copy-on-write?

[Vladimir Saveliev]

Hello

On Fri, 2005-02-11 at 11:18, Roland Paterson-Jones wrote:
> Hi
> 
> I have an application where I want to make relatively frequent copies of 
> a large file, and the copies will remain largely similar to the original.
> 
> It seems to me that a file-level copy-on-write would support this well.
> 
> So, does reiserfs support anything like this?
> 

No.

> If not, can I implement this easily (how easily ;) ) with a plugin.
> 
I guess you mean plugin for reiser4?
You probably can but I do not think that it would be easy.

> Any ideas and pointers greatfully received

I think it would be easier to modify the application.
You should probably start with detailed definition of your COW protocol.

> Thanks
> Roland
> 
> 

Re: File-level copy-on-write?

[David Masover]

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Vladimir Saveliev wrote:
[...]
|>If not, can I implement this easily (how easily ;) ) with a plugin.
|>
|
| I guess you mean plugin for reiser4?
| You probably can but I do not think that it would be easy.

But, AFAIK it's in the long-term plans, as it's needed for snapshots,
which AFAIK are also in the long-term plans.

|>Any ideas and pointers greatfully received
|
|
| I think it would be easier to modify the application.
| You should probably start with detailed definition of your COW protocol.

I, for one, would appreciate it if you (or someone) would look at how
difficult it would be to implement as a plugin, because it's got to be
done eventually, and won't be done soon by the Namesys guys (AFAIK they
are working on stability right now).

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