Daily Archives: 27.Aug.11

Fix Time Machine Sparsebundle NAS Based Backup Errors

Time Machine

This is a modification of an original post for use when you have a corrupt sparsebundle backup on a NAS (as opposed to an external drive attached to a router) and it needs to be repaired. The NAS is likely a hardware product from the likes of Netgear, Synology, Buffalo or QNap – or for those of us with a home-grown backup server running FreeNAS.

The error you may see is “Time Machine completed a verification of your backups. To improve reliability, Time Machine must create a new backup for you.” This can be fixed by following the below.

From your Mac, connect to the network share that houses the sparsebundle.

At the top level of the drive are the various sparsebundles that make up your individual computer backups.

Do not double click on these sparsebundles or try to repair with Disk Utility.

Open Terminal and then switch to root by typing

sudo su -

and then enter your password.

The verication that has already run has marked your sparsebundle as bad, so first we need to make it look normal.

From the command line

chflags -R nouchg /Volumes/{name of your network share}/{name of}.sparsebundle

This may take a little while.

Now type

hdiutil attach -nomount -noverify -noautofsck /Volumes/{name of your network share/{name of}.sparsebundle

You will then see something like

/dev/diskx Apple_partition_scheme
/dev/diskxs1 Apple_partition_map
/dev/diskxs2 Apple_HFSX

Where x is the disk id for the external disk. You are interested in the one labeled Apple_HFSX or Apple_HFS. It might be 2, 3, 4 or higher.

At this point, I have found that the filesystem check is already happening. You can check for activity by tail’ing the fsck_hfs.log

tail -f /var/log/fsck_hfs.log

If fsck is going then in my experience it will be able to repair the sparsebundle. Go away for a few hours and let it chug away.

When it is done, you will either see

‘The Volume was repaired successfully’


‘The Volume could not be repaired’

If the latter you can run disk repair again:

fsck_hfs -drfy /dev/diskxs2

(Optionally if you have the available RAM, you can set a RAM cache in the command above to help speed up this command like so:

fsck_hfs -drfy -c 750 /dev/diskxs2

This will use 750MB of RAM – feel free to change this amount to best fit your system (amount of RAM vs size of your Time Machine Sparsebundle). If you are unsure about this, use the first command.

Make sure to replace x with whatever number your disk is from the output above.

The letters “drfy” tell the filecheck utility different things. d for ‘Show Debug’ – r for ‘Rebuild Catalog Tree’ – f for ‘Force’ and y for assume ‘yes’ to any prompts.

Now go do something for an hour or two. Come back and

tail -f /var/log/fsck_hfs.log

If all went well, the last output you will see is

‘The Volume was repaired successfully’

Now you need to type
hdiutil detach /dev/diskxs2

You can redo the above for any other Time Machine sparse bundles you have permission to modify while you have the network share attached to your computer.

Final step.

When complete, you need to edit an plist file within the sparsebundle that records the state of the backup. On the top level of the sparsebundle find a file called com.apple.TimeMachine.MachineID.plist. Edit it and remove these two nodes


Finally you want to change



Now you can eject the network share and have Time Machine give it another go. After the (long) verification step, backups should proceed once again.


Ideally this should be done over a gigabit wired network connection. Do not attempt using Wi-Fi. You also want to make sure your machine does not go to sleep during the above operation.

[Update: 1.1.2013]

I appreciate all the warm feedback from people all over the world who have been helped by this post. This site helps to fund my hobbies, so if this post has helped you please consider a USD $1.99 donation to my hobby fund.


[Update: 12.23.2012]

If after running the initial

fsck_hfs -drfy /dev/diskxs2

command you get a message in the fsck_hfs.log along the lines of

RebuildBTree – record x in node y is not recoverable.

then try

fsck_hfs -p /dev/diskxs2

followed by

fsck_hfs -drfy /dev/diskxs2

And see if that works.  It did for me today.


iTunes Home Theater – How to integrate with iPad, iPhone, other iOS devices, AV Receiver and TV

I’ve been asked a few times to explain how iTunes runs everything in the house. So here it is.

We have an always-on computer (a mac, but could be an old PC) – which is always running iTunes and this is where we keep all of our homemade and purchased media – Movies, TV Shows, Music.

The iTunes folder is stored on an external disk that has an internal RAID-1 mirror (One drive can die and you are ok) — like this one

LaCie External Raid

Each iPod, iPad, iPhone in the house that wants media, syncs to this machine – with the relevant tabs in iTunes adjusted per device.


We have two Apple TV’s – one for each TV. We have an old model and a new model. New model is here:

Apple TV 2

The new Apple TV is connected via HDMI to the AV Receiver (Yamaha RX-V667) and the receiver is then connected to the main TV set. Apple TV is also connected to the house network.

Using the Apple TV software everything on the aforementioned iTunes computer can be watched on the main TV on demand. Apple TV can also buy individual TV Shows or Movies from the iTunes store and you watch them on your TV. The new Apple TV also allows you to stream shows from Netflix. You also have access to YouTube, Vimeo, Flickr and MLB tv and NBA tv streaming.

As a bonus, if the iTunes computer is a mac and you have iPhoto – you can setup Apple TV to use your digital photo library as a slideshow on the TV – which is nice to have just running in the background.

And another bonus, Apple TV becomes a ‘speaker’ destination for iTunes. From the iTunes computer you can play any of your music and then choose to stream to Apple TV and the sound will come out of your TV or home stereo (however your TV sound is setup). This is called Airplay – formerly called AirTunes. Another feature of Airplay is the ability to send video from the iTunes computer or your iPad straight to the TV for watching – pretty much any video you can watch on your iPad — YouTube/Vimeo/iTunes/etc.

I recently added outdoor speakers to the back deck and that was a little tricky as they would be run through the Yamaha receiver but I also wanted a separate volume control so they would not just be the same volume as what was playing in the Living Room. To solve this, I had to use another Airport Express (AX). So the Airport Express sits in the AV Cabinet and the Airplay name is ‘Back Deck Speakers’. The AX is then connected to the AV Receiver via a 3.5mm to RCA cable. On the iTunes computer, I then select the ‘Back Deck Speakers’ and turn on Zone 2 on the Yamaha and I have amplified sound that is separate from what is playing on the Yamaha.

Finally, Apple has a free Remote app for iPad/iPhone/iPod Touch that can control all of the above and also makes any typing you need to do on the Apple TV much easier.