Mac – Time Capsule/Time Machine volume slow to process with tmutil

backupterminaltime-capsuletime-machine

My 2TB Time Capsule has functioned as our home router and backup device for years.

It's not very fast at backing up over network, but since this is a passive activity it's never been a problem.

I went into the volume to try to clean it up a bit and it's really slow to respond over both GUI and command line.

I'm within close wireless range (5 meters, direct line of sight)
Pinged packets return in < 1ms, I don't think it's the wifi
Browsing the network disk in Finder is very slow, it takes 20+ seconds just for folders and files on the disk to populate
tmutil responds just as, if not more slowly (as does simply running ls in the Time Machine volume)
Most importantly, trying to delete items via tmutil is way too slow. Usually taking over 45 minutes to delete a 500MB backup.

(I realize that these backups are stored as diffs rather than complete files, so there's some degree of logic that is going into the deletion process, but this still seems absurd)

I looped through my backups and wanted to delete most of them, like so:

sudo tmutil delete /Volumes/Time\ Machine\ Backups/Backups.backupdb/foo/2016-08-10-015922

I have 130 backups I want to remove this device and even at an optimistic 30 minutes per deletion, that's still 65 continuous hours of this script running (for something that should take less than an hour IMO).

What's wrong?

Base Station/Time Capsule OS version: 7.6.9 [11] (latest)

Best Answer

I don’t think anything is wrong. The hard link directory nature of a time machine backup is extraordinarily iops constrained and coupled with the limited power of the disk controller in AirPort, you’re far better off copying off the files you want to keep and then erasing the volume.

Each backup has a directory entry for each and every file present on the source so each backup interval deletion is actually a ton of work (whereby a ton is defined as 250,000 directory entries with ACL, permissions, date metadata, etc...)

Your network measures are spot on, and I worry your TimeCapsule drive could be failing if a simple ls is lagging so badly.

Modes and ownership

Ideally, use chmod(1) and chown(8) to have the mode and ownership, of the copy of the disk image, consistent with how Mountain Lion normally creates a local disk image for Time Machine.

Example

GPES3E-gjp4-1:~ gjp22$ sudo ls -al /Volumes/tall/com.apple.backupd/GPES3E-gjp4-1.sparsebundle/
Password:
total 16672
drwx------@ 3 root   staff     10  7 Jun 19:07 .
drwxr-xr-x  8 gjp22  staff     10  6 Jun 18:57 ..
-rw-r--r--  1 root   staff    500  7 Jun 18:03 Info.bckup
-rw-r--r--  1 root   staff    500  7 Jun 18:03 Info.plist
drwx------  2 root   staff  78855  7 Jun 19:07 bands
-rw-r--r--  1 root   staff    444  7 Jun 18:02 com.apple.TimeMachine.MachineID.bckup
-rw-r--r--  1 root   staff    444  7 Jun 18:02 com.apple.TimeMachine.MachineID.plist
-rw-r--r--  1 root   staff   1473  6 Jun 21:28 com.apple.TimeMachine.Results.plist
-rw-r--r--  1 root   staff  10698  6 Jun 22:24 com.apple.TimeMachine.SnapshotHistory.plist
-rwx------  1 root   staff      0 19 Mar 19:36 token

– and for each band, you should have:

-rw-------  1 root  staff

Attaching the copy of the disk image

With Terminal, for the example above:

sudo hdiutil attach -readonly /Volumes/tall/com.apple.backupd/GPES3E-gjp4-1.sparsebundle/

If you use Terminal from within Recovery OS: you'll probably not need the sudo prefix to the command.

Additional detail

… whether I can still restore …

You require:

a copy of a Time Machine destination, a copy that will be good for restoration
not an additional Time Machine destination.

Assumption

You wish the copy to be usable, for restoration only, in the event of loss or failure of the Time Capsule.

If the disk is attached from a local image where modes and ownership vary from the norm for a local image:

OS X or Recovery OS might use that disk without difficulty; I can't be certain.

Thoughts

If you're preparing for the possibility of loss or failure of a Time Capsule – and restoration from a copy of what was there – then think a step further, to backing up without the original Time Capsule. (If you wish the copy to be writeable by Time Machine, that could be a separate question.)

All things considered

It's probably quicker and simpler to use the external hard disk, or a part, as a Time Machine destination.

Mac – Can Time Machine backup two HDDs to Time Capsule

Yes, by default Time Machine will backup all internal HDD's whether they are SSD or not. Just make sure your time capsule is big enough.