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LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
PostgreSQL 9.3 beta: Federated databases and more
LWN.net Weekly Edition for May 9, 2013
(Nearly) full tickless operation in 3.10
What is a wandering tree? I note that there's no wikipedia article on it and the first few
google results don't seem to be relevant...
Posted Apr 3, 2008 8:52 UTC (Thu) by ahunter (guest, #51399)
There is some info here:
Posted Apr 3, 2008 9:57 UTC (Thu) by deleteme (guest, #49633)
Actually managing the entire directory tree as a wandering tree would be expensive; beyond that, files with multiple hard links break the tree structure and make wandering trees much harder to implement. So the actual tree implemented by LogFS just has two levels. There is an "inode file" containing the inode structures for every file and directory existing within the filesystem; each inode then points to the associated blocks holding the file's data. Directory entries contain a simple integer index giving the inode offset within the inode file. So changes to an inode only require writing the inode itself and the inode file; the rest of the directory structure need not be touched.
Posted Apr 8, 2008 10:43 UTC (Tue) by saffroy (subscriber, #43999)
It's been a while since I read about it, but this approach sounds similar to the method used
by WAFL, the filesystem used by NetApp and described here:
This is great for snapshots, but I think it's patented (maybe someone can confirm?).
Speaking of patents, from what I read in this article, I don't see what's different between
UBI and FTL, the latter being patented too.
Posted Apr 11, 2008 16:48 UTC (Fri) by anton (guest, #25547)
Posted Apr 4, 2008 14:36 UTC (Fri) by rwmj (subscriber, #5474)
They've rediscovered a functional programming technique which
has been used for ages called 'zippers'.
There is even a Haskell "OS" (actually, filesystem) written
using this technique, which has some neat properties like
multiple versions, rollback and transactions:
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