Linked by Thom Holwerda on Sat 24th Feb 2007 21:25 UTC, submitted by mdoverkil
BSD and Darwin derivatives Apparently, Matt Dillion has decided to roll his own filesystem for DragonFly. "Here is my initial outline of the filesystem design. It is open for discussion. Please feel to ask questions for anything you do not understand. I do not intend to start coding anything for at least two weeks. There are currently two rough spots in the design. First, how to handle segment overflows in a multi-master environment. Such overflows can occur when the individual masters or slaves have different historical data retention policies. Second, where to store the regeneratable indexes."
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I am confused ...
by deb2006 on Sat 24th Feb 2007 22:55 UTC
deb2006
Member since:
2006-06-26

I always thought Dragonfly was going to use zfs ... Why is there need for another filesystem when the really big one - zfs - is on the market???

Reply Score: 3

RE: I am confused ...
by aliquis on Sun 25th Feb 2007 03:12 in reply to "I am confused ..."
aliquis Member since:
2005-07-23

Because it doesn't do what he need?

Reply Parent Score: 5

RE: I am confused ...
by butters on Sun 25th Feb 2007 06:01 in reply to "I am confused ..."
butters Member since:
2005-07-08

ZFS is indeed a very advanced filesystem. However, filesystems are very tightly associated with the virtual memory system through which they operate. ZFS was designed on the assumption that the OS will enforce cache coherency through mutual exclusion mechanisms. DragonFly implements cache coherency through a fundamentally new model of process and memory management that implicitly addresses the issue of cache coherency.

Could DF fool ZFS into believing that memory can only be accessed under certain conditions? Of course, and this is what they do currently. But this is far from optimal, and it prevents DF from scaling efficiently to vastly multi-node systems.

Reply Parent Score: 5