Do not trust your Time Machine backups

That's so wrong! I installed beta software, yes, now say my hard drive crashed, I would have got the exact same issue : files are missing from the backup, you can't blame the beta, really.

You are basically telling me : oh, yes, well, if you need a reliable backup, make a clone... Well, that's my point, Time Machine should provide reliable backups at all times, unless an unexpected event corrupts the drive, and in that case, I want a way to check.

See, I understand file system breaks, it happens, so I would like that Apple checks the backup on regular intervals or let me do it myself, I would accept that

I don't know if both disks are working properly, and I would almost say that's not the point.

Let me explain : Time Machine backups were running without warning, to me, it means everything is fine. There should be some kind of regular verification, and a way to manually check that a given backup is valid.

I ran a disk utility Verify on the TM drive, it finished without issue.

Yes, the files were missing from the TimeMachine disk, for example, /usr/share/shadbox was complete if I looked at a backup from end january, but most files were missing looking at any after that. Same thing for /System/Library/CoreServices/logind

I did a complete restore because I installed a beta release of the OS, I'm a developer, but realizing that one key product I need was not working (VMware Fusion), I decided to roll back. Following that bad experience, I searched for a way to verify backup and was astonished to find out that there is no such thing, Apple provides a flawed software with no mean to very integrity of the backups, that's just very, very bad.

To be completely honest, I should mention that while installing beta software, a few file system inconsistencies were detected and fixed by the installer, maybe that is the cause, but in no condition should you have a system that works perfectly in one hand, and a corrupted backup on the other hand, especially if the used backup disk is healthy.

So, Time Machine breaks, silently, it happens... This is bad enough... And the only way I have to make sure a backu is usable is to go into the TM hard drive and manually check my files...

This is awesome, thanks Apple!

So, I'm a developer, I guess I can write my own weekly script to compare files and dates and report any missing files from the backup that would have not been created recently...

That's a good point.

Well, honestly, I think I can affort 99%, as long as I can manually check from time to time that all data are stored, that's a process that can be achieved with a 100% hit rate and can provide confidence.

I had a time machine Backup (Mavericks)

I unplugged my TM disk

I installed "you-know-who" (breaking NDA would actually be talking about features or specifics of you-know-who, the fact there is such a beta is actually public and not NDA)

I wanted to revert

I plugged the disk back and boot off-it to restore my backup.

So, to clarify, and since it looks like it became a sensitive matter in that topic : I'm not breaking any NDA.

The only way to verify a backup, is to compare byte-for-byte each file in the live file system with the one backed up. That's the only way.

Restoring a backup is good enough to see if you can boot your system off your backup, doesn't even mean the backup is current or if it contains all your files.

Plus, to do that, you need another drive with enough space to hold the restoration... really ?

So, back to the basic : verifying a backups consists of checking every single file with the backup... pretty intense right? Maybe I'm not asking that much. But maybe an option in Time Machine or Disk Utility that would do a "Basic consistency check" (say, check files are here and dates matches) or "Deep consistency check" (heavy, painful, and lenghty file comparison), that, is what I consider reliable solution.

From now on, I'm back in the 90's having to manually manage my backup because Apple sold me a solution that, not only is not reliable, but is not auditable by itself (meaning I have to check it myself).

I would actually do better than that and continue using Time Machine, but not without running a monthly file comparison. I wish I had enough time to make a software and sell it to people tha care about their backups!

I will reward your answer since this is the one that makes more sense, and unfortunately, I don't think there is much more to say on that matter, that's a shame.

It is 2014, I work for a storage vendor that provides reliable, block-level, deduplicated and efficient backup of your your storage for many years, but a multi billion company like Apple still relies on a ancient file system, archaic backups, not even better than file incremental backups, just easier to browse (directory level hard links... really? I mean, it is 2014... time to move on).

I still love Apple, I really do, I'm just smacking myself for trusting them for more than they can do, fooled by the marketing slides :-)

Well, I was naïvely thinking like a basic user : Apple sells me that solution to backup my data, as long as it is running and that little menu says "Last backup today at 2pm", I'm safe.

Only power users like me (now) would doubt the ability of the backup to be restored, that especially what makes it a system *not* aimed at newbies.

Thanks for your comment Michel