[Info-vax] Re; Spiralog, RMS Journaling (was Re: FREESPADRIFT)

[Paul Sture]

On 2016-06-17, Stephen Hoffman <seaohveh at hoffmanlabs.invalid> wrote:

>
> q.v. 
> <http://arstechnica.com/apple/2016/06/digging-into-the-dev-documentation-for-apfs-apples-new-file-system/>

The following sentence leaped out:

"A feature called "fast directory sizing" is purported to give macOS a
fast way to query the size of a directory and all its child objects,
rather than having to wait while a bunch of stat calls complete."

Rather useful when determining how much space is required for a
Time Machine Backup, I imagine.

cf VMS only storing the block sizes of files rather than the number of
bytes; this can be problematic for utilities ported from a system which
has an easy/cheap way to supply the exact size in bytes.

FWIW, from time to time a process running 'du' consumes high amounts of
CPU on OS X Server.  Observations indicate that it's part of Time
Machine backing up the OS X Server data itself (not that I have much of
that in the grand scheme of things).  I can see why Apple want to
implement the above feature.

-- 
There are two hard things in computer science, and they are cache invalidation,
naming, and off-by-one errors.