Re: flushing HFS cache to disk
Re: flushing HFS cache to disk
- Subject: Re: flushing HFS cache to disk
- From: Mark Day <email@hidden>
- Date: Tue, 29 Nov 2005 13:32:44 -0800
On Nov 29, 2005, at 12:03 PM, email@hidden wrote:
that's what sync(2) does.
It doesn't seem to.
Beware that sync(2) is an asynchronous call. It just begins the
flushing of data to all volumes. If you're reading the disk
immediately, the changes may not have been written yet.
What information in particular do you not think is getting flushed
to disk.
E.g. when I delete a file this change is not written to the HFS
catalog tree after calling sync() - the tree still contains this
entry.
And why in the world are you accessing the filesystem through the
raw device instead of the mounted filesystem. Even if you sync(2),
you're never going to get a coherent snapshot of the filesystem that
is mounted read/write.
I need to get a list of all files with related information. Reading
this list from the HFS catalog tree is much faster than looping and
stat-ing through all directories (e.g. with 500.000 entries: seconds
compared to minutes) - while both will not result in a coherent
snapshot.
Have you tried FSCatalogSearch or PBCatSearch in Carbon, or searchfs
(2) at the BSD layer? On HFS, they end up reading the catalog B-tree
in file order, not in hierarchical order. (That's probably what your
code is trying to do.) Note that these calls aren't supported on all
volume formats.
-Mark
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