Garbage Collection Schemes

[John Andersen <jsa-MJZuZBXGww0Jmq/UkTHWNaxOck334EZe@public.gmane.org>]

I am new to NILFS, so bear with me.

I would like to ask, (without reading the entire archive of messages) if
any thought to other garbage collection schemes has been contemplated.

For instance: This file system looks like it might be very useful for 
certain types of environments where N sequential revisions of documents
must be maintained, regardless of the  age or how any given document relates
to other documents.

Checkpoints do not seem to do this.

I would like to see garbage collection options that allow (for example)
10 copies retained (of EACH file), each bearing different dates.  

Garbage collection would erase the 11th (oldest copy) if, (and only if) the 
other 10 all had different dates.  This prevents the situation where one user 
(or rogue process) re-saving a document 15 times a day wipes out all prior 
copies.

An option might be garbage collection not based on a NUMBER of iterations
but rather a period of time (3 years, 7 years, etc, while still purging same 
date (or same hour, minute, etc) copies.

This type of garbage collection is found almost nowhere, and this
file system seems to be the closest possible candidate to do this.

There are applications, where a consistent representation of all 
files at a specific point in time (snapshot or checkpoint) is LESS
important than the ability to roll back individual documents to 
a number of prior iterations or a number of years.

Legal documents, financial records, code version archiving, etc, all
have these requirements.


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John Andersen	
Screenio.com