What on earth is it doing in this stage? It takes minutes, for small 
backups it often takes longer than copying the data it's punted across. 
Any ideas what's going on?


Cheers,
Ian

Ian McCall  wrote:

> What on earth is it doing in this stage? It takes minutes, for small 
> backups it often takes longer than copying the data it's punted across.
> Any ideas what's going on?

The equivalent of 'optmising' or defragging? i.e, moving stuff about and
tidying up the free space?
-- 
Peter

Ian McCall  wrote:

> What on earth is it doing in this stage? It takes minutes, for small 
> backups it often takes longer than copying the data it's punted across.
> Any ideas what's going on?

My guess is that the main thing it does then is create hard links into
previous backups for all unchanged files and folders, which will take a
varying amount of time depending on the degree to which the latest
backup differs from the previous one.

To take a simple example, if only one file changed, it would need to
create hard links for every other file or folder in the same folder as
the changed file, and repeat that for every parent directory up to the
root level.

A typical backup will have many files changed in many places, so this
procedure must be repeated for each folder in which any changes were
made.

If a change occurred in a folder with lots of files (e.g. a Mail inbox
with thousands of messages) it will need to create lots of hard links.

It doesn't need to navigate down into a folder which had no changes - a
single new hard link for the folder itself is sufficient.

-- 
David Empson
dempson@actrix.gen.nz

"Ian McCall"  wrote in message 
news:6i1fflFoh3s8U1@mid.individual.net...
> What on earth is it doing in this stage? It takes minutes, for small 
> backups it often takes longer than copying the data it's punted across. 
> Any ideas what's going on?
>

I thought it was backing up all tempory files including caches as
part of it's every hour task, then of course it has to delete these files
again at next backup.
I tend to use mine as a once every 2-3 days backup or when I'm doing
something important ratehr than keeping it on all the time.

On 2008-09-01 07:25:40 +0100, peter@cara.demon.co.uk (Peter Ceresole) said:

> Ian McCall  wrote:
> 
>> What on earth is it doing in this stage? It takes minutes, for small
>> backups it often takes longer than copying the data it's punted across.
>> Any ideas what's going on?
> 
> The equivalent of 'optmising' or defragging? i.e, moving stuff about and
> tidying up the free space?

Sort of: the UI hides that several phases happen during a TM "backup", 
only one phase of which copies changed files to the TM disk. The other 
phases coalesce ("thinning") old backups, and David's guess about the 
merging of the new backup with the previous backup seems reasonable too.

Here's a snippet of this evening's log after not backing up for two weeks:

Sep  7 18:25:40 No pre-backup thinning needed: 2.40 GB requested 
(including padding), 246.76 GB available
Sep  7 18:37:13 Copied 66440 files (1.2 GB) from volume Macintosh HD.
Sep  7 18:37:33 No pre-backup thinning needed: 1.03 GB requested 
(including padding), 245.52 GB available
Sep  7 18:37:51 Copied 632 files (1.6 MB) from volume Macintosh HD.
Sep  7 18:38:02 Starting post-backup thinning
Sep  7 18:43:14 Deleted backup /Volumes/Time 
Machine/Backups.backupdb/aluminium/2008-07-25-072523: 245.60 GB now 
available
Sep  7 18:43:14 Post-back up thinning complete: 1 expired backups removed
Sep  7 18:43:17 Backup completed successfully.

So there's about 12 mins worth of copying lots of changed files, 
followed by about a minute of "pre-backup thinning", and then 5 minutes 
of "post-backup" thinning.

Cheers,

Chris