Re: [OT] bad records in HFS+ volume
Re: [OT] bad records in HFS+ volume
- Subject: Re: [OT] bad records in HFS+ volume
- From: Dave Camp <email@hidden>
- Date: Thu, 29 Jul 2004 14:26:10 -0700
On Jul 29, 2004, at 12:57 PM, Gerriet M. Denkmann wrote:
The Extents Overflow File of one of my HFS+ partitions has a few
records referencing fileIDs (aka NSFileSystemNumber or unique catalog
node ID (CNID) ) which do not exist (i.e. are not in the Catalog
File).
Disk Utility (and fsck) do have no problem with this and report no
error.
If the CNIDs are low numbers, those might be entries for other file
system structures which are not tracked in the Catalog (overflow
entries for the catalog tree, extents tree, volume bitmap, bad blocks,
hot zone stuff, etc).
Otherwise, I'd be surprised that Disk Utility did not flag the orphan
extents as errors. While they don't hurt anything (assuming the volume
bitmap is in sync with the extents), it's space that's essentially
wasted.
How do you know you have orphaned extents?
But what will happen when the CNID wraps around and these
non-existing iIDs will be used again?
Will the file system notice that dead records exist in the Extents
file and remove them?
Or will a terrible confusion be the result?
Currently I create about 1 million IDs per year, so the CNID
wrap-around is not really imminent.
I'm not sure what happens when you exhaust the range of CNIDs (I've not
seen it done before). The filesystem keeps track of the last number
used and adds one to get the next number to use when a new file or
directory is created. Since there is no list of what's used and not
used (other than the hundreds of thousands of catalog entries) I'd
expect the filesystem to just return an error when you hit the last
one. If the filesystem can no longer just "add one" to determine the
next one, I would expect the overhead of determining what the first
unused CNID is to be too great.
Dave
---
The path of least resistance, it's not just for electricity any more.
_______________________________________________
cocoa-dev mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/cocoa-dev
Do not post admin requests to the list. They will be ignored.