04-08-2012, 07:18 AM

Originally Posted by pendlewitch

Some good points here thank you.

This thread raises some very important questions that have bothered me since I had a system problem whilst doing a first time TM back up on a new external HD. I was advised that the TM back up was probably corrupt.

How do we know that a regular TM back up is not corrupt? Can we test the integrity of the back up ? Should we be running Disk Utility regularly on the external HD ? (That in itself may be a facile question but how many of us do it?)

I share your concern but I guess Time Machine has that covered.
What I see happening ( automatically ) is that sometimes Time Machines says " Verifying Backup " ( and then a rolling percentage ) prior to " Preparing backup ".
For me the verifying step takes about 45 minutes ( Wireless ).
I am not an expert and I don't know the inside of that process, but it looks like TM is checking the integrity of its backup database somehow.
That leaves the physical integrity of the disk and there, I guess the usual DiskUtility stuff comes in. I am not an expert but your points are very valid.
So far, TM has saves my bacon a couple of time when I accidently deleted a complete folder instead of a file :-) so I trust the Apple engineers a lot.


Cheers ... McBie

04-08-2012, 10:16 AM

Originally Posted by McBie

I share your concern but I guess Time Machine has that covered.
What I see happening ( automatically ) is that sometimes Time Machines says " Verifying Backup " ( and then a rolling percentage ) prior to " Preparing backup ".
For me the verifying step takes about 45 minutes ( Wireless ).
I am not an expert and I don't know the inside of that process, but it looks like TM is checking the integrity of its backup database somehow.
That leaves the physical integrity of the disk and there, I guess the usual DiskUtility stuff comes in. I am not an expert but your points are very valid.
So far, TM has saves my bacon a couple of time when I accidently deleted a complete folder instead of a file :-) so I trust the Apple engineers a lot.


Cheers ... McBie

Thanks McBie,

Some sources that I have read say that there is no verification phase in the TM process, it doesn't look like there is one in a standard back up in the sample I attach. I've gone back a week and can't find anything more interesting than this.

What I have discovered is that if you hold down the 'Option' (alt) key whilst clicking the cursor on the TM icon in the menu bar it will bring up a 'Verify BackUps' option, which in my instance is greyed out (I'm running Lion) and don't know why this would be unless there is no need?
There is also no Disk verification phase either so I guess we need to do this separately and when TM is turned off.

04-08-2012, 11:07 AM

You can verify your backups from the TM menu bar icon. Simply hold down option and click the icon to reveal a "Verify Backups" menu option.

04-08-2012, 11:11 AM

Originally Posted by vansmith

You can verify your backups from the TM menu bar icon. Simply hold down option and click the icon to reveal a "Verify Backups" menu option.

But my option is greyed out as per above.

04-08-2012, 11:20 AM

Originally Posted by vansmith

You can verify your backups from the TM menu bar icon. Simply hold down option and click the icon to reveal a "Verify Backups" menu option.

My "Verify Backups" menu option is greyed out.

04-08-2012, 11:23 AM

Originally Posted by pendlewitch

But my option is greyed out as per above.

Haha, whoops, missed that.

After some investigation, the option is only available for networked TM backups. I really wish that was more clear.

04-08-2012, 11:29 AM

Originally Posted by vansmith

Haha, whoops, missed that.

After some investigation, the option is only available for networked TM backups. I really wish that was more clear.

That's OK. The external HD I use for Time Machine backups is directly attached to my iMac via USB.

04-08-2012, 12:07 PM

This is what I get when it is doing verification.
Don't know why it does that or can not predict when it does that .....

Apr 1 15:55:44 MDNMBP com.apple.backupd[37845]: Attempting to mount network destination URL: afp://Marc%20De%20Neef@MDN-TC01.local/TC01-DSK
Apr 1 15:55:46 MDNMBP com.apple.backupd[37845]: Mounted network destination at mountpoint: /Volumes/TC01-DSK using URL: afp://Marc%20De%20Neef@MDN-TC01.local/TC01-DSK
Apr 1 15:55:49 MDNMBP com.apple.backupd[37845]: Running backup verification
Apr 1 15:55:51 MDNMBP com.apple.backupd[37845]: QUICKCHECK ONLY; FILESYSTEM CLEAN
Apr 1 16:48:12 MDNMBP com.apple.backupd[37845]: Backup verification passed!
Apr 1 16:48:16 MDNMBP com.apple.backupd[37845]: QUICKCHECK ONLY; FILESYSTEM CLEAN
Apr 1 16:48:19 MDNMBP com.apple.backupd[37845]: Disk image /Volumes/TC01-DSK/MDNMBP.sparsebundle mounted at: /Volumes/Time Machine Backups
Apr 1 16:48:19 MDNMBP com.apple.backupd[37845]: Backing up to: /Volumes/Time Machine Backups/Backups.backupdb
Apr 1 16:49:36 MDNMBP com.apple.backupd[37845]: 1.49 GB required (including padding), 33.86 GB available
Apr 1 16:54:36 MDNMBP com.apple.backupd[37845]: Copied 16409 files (692.0 MB) from volume Macintosh HD.
Apr 1 16:54:36 MDNMBP com.apple.backupd[37845]: 552.7 MB required (including padding), 33.21 GB available
Apr 1 16:55:07 MDNMBP com.apple.backupd[37845]: Copied 661 files (26.6 MB) from volume Macintosh HD.
Apr 1 16:55:10 MDNMBP com.apple.backupd[37845]: Starting post-backup thinning
Apr 1 16:56:03 MDNMBP com.apple.backupd[37845]: Deleted /Volumes/Time Machine Backups/Backups.backupdb/MDNMBP/2012-02-17-194645 (64.9 MB)
Apr 1 16:56:03 MDNMBP com.apple.backupd[37845]: Post-back up thinning complete: 1 expired backups removed
Apr 1 16:56:04 MDNMBP com.apple.backupd[37845]: Backup completed successfully.
Apr 1 16:56:08 MDNMBP com.apple.backupd[37845]: Ejected Time Machine disk image.
Apr 1 16:56:08 MDNMBP com.apple.backupd[37845]: Ejected Time Machine network volume.


Cheers McBie

04-08-2012, 01:50 PM

Originally Posted by vansmith

Haha, whoops, missed that.

After some investigation, the option is only available for networked TM backups. I really wish that was more clear.

No probs van. Just getting my head around it. I'd read that it was Time Capsule specific somewhere earlier.

So the way I'm looking at it, I need to build a disk verify/repair for the TM backup HD into my maintenance regime , check the backed up folders and files on the HD randomly to see if they are what they say they are and do an occasional restore using a few of those files.

04-09-2012, 03:17 AM

Originally Posted by McBie

This is what I get when it is doing verification.
Don't know why it does that or can not predict when it does that .....

Not sure either..but it looks like a network drive specific regime. Mine's wired.
It would help if we could find a definitive explanation for what's going on.

04-09-2012, 06:35 AM

Maybe TM is doing this verification only over wireless.
I will search around a little bit and when I find something, I will post back.

04-13-2012, 12:53 AM

Originally Posted by Oneironaut

For things I want to backup permanently, I create a separate folder on my Time Machine drive and keep them on there. At any given point I have two of everything I need. I've never had a hard drive crash on my, but if I did, I'd go out and replace it immediately so I'd still have two of everything.

yeah i think that is the best way to go until we all transition into SSD disk drives.

04-14-2012, 05:41 AM

So to summarize, this is the strategy others have adopted and I am assembling (credit to chas):

1. One external hard drive for hourly Time Machine backups, excluding some big files that would bog my iMac every hour.
2. Another external hard drive for manual periodic backups (archiving) of big files and other critical files when I want more redundancy. And Aperture vault backups.
3. Another external hard drive for a periodic full clone of the hard drive using Super Duper or Carbon Copy (need to pick one).
4. A subscription to an offsite backup cloud service.

This method:

• Allows for recovering recent versions (Time Machine).
• Archives critical files redundantly.
• Creates a backup option in case the local backup/archive external hard drives are lost in a disaster.
• Creates a bootable clone that would get me up and running in minutes if the iMac's main hard drive failed, then I could use the Time Machine backup to fill gaps since the last time I made a clone.

04-14-2012, 08:00 AM

Originally Posted by Demapples

So to summarize, this is the strategy others have adopted and I am assembling (credit to chas):

1. One external hard drive for hourly Time Machine backups, excluding some big files that would bog my iMac every hour.
2. Another external hard drive for manual periodic backups (archiving) of big files and other critical files when I want more redundancy. And Aperture vault backups.
3. Another external hard drive for a periodic full clone of the hard drive using Super Duper or Carbon Copy (need to pick one).
4. A subscription to an offsite backup cloud service.

This method:

• Allows for recovering recent versions (Time Machine).
• Archives critical files redundantly.
• Creates a backup option in case the local backup/archive external hard drives are lost in a disaster.
• Creates a bootable clone that would get me up and running in minutes if the iMac's main hard drive failed, then I could use the Time Machine backup to fill gaps since the last time I made a clone.

This is what a hunter will do to kill a deer with automatic gun with 16 shots a minute, foul proof.