DragonFly kernel List (threaded) for 2004-01
Re: Background fsck
Dan Melomedman wrote:
Matthew Dillon wrote:
:this is the outline of how to implement a background fsck for DragonFly.
:DR, this is somewhat more mature than what I wrote on Friday.
:The first alternative is using a journal for all meta-data updates. That's
:what most Linux filesystems are doing. The advantage is almost no time
:needed to bring a uncleanly unmounted filesystem back into a working state.
:The disadvantage is a steady slow down for _all_ meta-data updates.
This actually doesn't slow down meta-data updates all that much,
because the journal is linear it takes only one seek to update while
you might need hundreds of seeks to update the meta-data in its
individual locations on the disk.
This is really the best way to do it, I think.
I've read somewhere that it can actually speed some specific cases up.
Perhaps of interest in this regard:
Jonathan S. Shapiro, Jonathan Adams
"Design Evolution of the EROS Single-Level Store"