lkml.org 
[lkml]   [2003]   [Oct]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Transparent compression in the FS
jw schultz wrote:
>>Consider a simple key-value map, where "$hash $n" is the key and the
>>value is the block of data. Only three operations need occur:
>>* if hash exists (highly unlikely!), read and compare w/ raw data
>>* write new block to disk
>>* add single datum to key-value index
>
>
> Nicely described, but each block now needs a reference count
> which is incrmented if the raw compare yields a positive and
> decremented when a reference to it receives a write.

Yep. I'm pondering a sort of a closely-interconnected distributed cache
for archival storage, so I have to care about refcounts on remote
servers, too.


> It may help to also have a reverse reference somewhere
> from the block to the hash.

I think I can avoid this...


>>Inode block lists would need to be updated regardless of any collision;
>>that would be a standard and required part of any VFS interaction. And
>
>
> Under current schemes if i overwrite an already allocated
> block of a file the block list need not be updated unless
> the block is relocated. But that is a nit.

Yep. For a networked filesystem, this is less annoying and clients will
not normally notice any slowdown from this.

Jeff



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:58    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site