[lopsa-tech] mac os/x fragmentation

[Andrew Hume]

as we upgrade to 10.4, we are finding our mac os/x nodes
are getting 'hfs_relocate: didn't move into metadata zone' diagnostics.
annoyingly, there doesn't seem to be a way to find out which filesystem
is affected, nor how to fix the underlying problem (if there is any).

does anyone know what the scoop is?

----
Andrew Hume (best -> Telework) [phone]
***@research.att.com (Work) [phone]
AT&T Labs - Research; member of USENIX and LOPSA

[Brandon S. Allbery KF8NH]

Post by Andrew Hume
as we upgrade to 10.4, we are finding our mac os/x nodes
are getting 'hfs_relocate: didn't move into metadata zone'
diagnostics.
annoyingly, there doesn't seem to be a way to find out which
filesystem
is affected, nor how to fix the underlying problem (if there is any).

First things first: did you try "Verify Disk" in Disk Utility?

[Andrew Hume]

yup; we tried all the obvious things like verify disk and fsck.

Post by Brandon S. Allbery KF8NH

Post by Andrew Hume
as we upgrade to 10.4, we are finding our mac os/x nodes
are getting 'hfs_relocate: didn't move into metadata zone'
diagnostics.
annoyingly, there doesn't seem to be a way to find out which
filesystem
is affected, nor how to fix the underlying problem (if there is any).

First things first: did you try "Verify Disk" in Disk Utility?
--
brandon s. allbery [linux,solaris,freebsd,perl]
system administrator [openafs,heimdal,too many hats]
electrical and computer engineering, carnegie mellon university
KF8NH

----
Andrew Hume (best -> Telework) [phone]
***@research.att.com (Work) [phone]
AT&T Labs - Research; member of USENIX and LOPSA

[Brandon S. Allbery KF8NH]

Post by Andrew Hume

Post by Brandon S. Allbery KF8NH

Post by Andrew Hume
as we upgrade to 10.4, we are finding our mac os/x nodes
are getting 'hfs_relocate: didn't move into metadata zone'
diagnostics.
annoyingly, there doesn't seem to be a way to find out which
filesystem
is affected, nor how to fix the underlying problem (if there is any).

First things first: did you try "Verify Disk" in Disk Utility?

yup; we tried all the obvious things like verify disk and fsck.

Rooting around in Apple tech notes, it looks like it's just an
informational message that a candidate for "hot file" relocation
wouldn't fit in the metadata zone's hot-file reserved space. Hot
file relocation is an optimization for small, frequently accessed
files based on a simple calculation that balances the amount of data
accessed recently against the file's size; the metadata zone can have
from 8K to 512M (depending on volume size) reserved for such files.
If the file won't fit in the reserved space, either because it's too
large or because the zone is already full, you'll get that message.

(In particular, the only relationship I see with regard to
fragmentation is that files moved into the metadata zone are
implicitly defragmented. Normal defragmentation is otherwise
unaffected by it.)

It might be possible to recreate volumes with larger hot file
storage, but I suspect it's not really worth it. I also suspect the
simplistic nature of the calculation might cause OSX to want to do
silly things if you e.g. have a large, heavily accessed database on
an HFS+ volume. In short, it doesn't look like anything to worry about.