Time Machine

[Al]

I wonder what happened yesterday?  I only got one back up at approx. 3 am all day.  That's not like TM.  Sounds like a special April Fools easter egg....

[Gregg]

...and now it's back to normal?

[Al]

Yeah, all yesterday, April 2nd, hourly back ups.  Just, on the 1st, only once.

[DaveF]

My Time Machine had made twelve back ups on April 1st. I had to use it late that day, so luckily I can verify the number of backups.   Now it only shows one for each day before yesterday (April 2), including April 1st.  

Like you, I was surprised since in preferences it says Time Machine keeps:

- Hourly backups for the past 24 hours
- Daily backups for the past month
- Weekly backups until your backup disk is full

I thought that March would have daily backups and April would have hourly backups until May arrived.  That would take a lot of disk disk though, so I guess it gives two days of hourly backups, daily backups for the previous thirty days and weekly before that until the disk is full.

Dave

[Al]

There it is!  Oh, how ironic..... I guess, it's a bit new to me.... Thanks Dave.

Since my HD is so small, TM machine probably had already discarded my other hourly back ups as I had noticed this pretty late on the 2nd.

Case closed.

[Xairbusdriver]

"Hourly backups for the last 24 hours." Time marches on, don't expect to see 25 daily backups at any time, much less 48. To me that says TM will delete all daily backups before 24 hours ago, leaving the last one of the day as the daily backup for the previous day. The previous day doesn't end until the end of "today," however. So, you should be able to get anything from the last 24 hours via TM. Those will, logically, span more than one calendar day, for a while.

Unfortunately, I'm find TM to be somewhat less than perfect. Several times, on some days, I get an alert saying the backup "failed." With absolutely no indication of why or how. Sure, there may be something in one of its logs but if it can be written there, why not write it in the dialog? I usually just force a backup manually and that always seems to work. Maybe some files being written while the backup is in progress and TM gets 'behind' in its tasks?

I have also had mixed results when attempting to find a file in its backup files. I've had no more than about a 75% success rate finding the file(s) I was looking for. Not because it was hidden or I had forgot where to look but because that day/hour had no files/backup!

It's still better than only daily backups, when it works, but it has got to work better before I'll trust it to take over for SD or CCC. Eye wand purfecktlei opureighting soffwhere!

OTOH, my System was not perfectly stable before this week...we'll see how things go after the reinstall.

edited a stoopid statement.

[DaveF]

The specs say hourly backups, but I assume this means every hour that the contents of the HD has changed.  Early on, out of curiosity, I checked the number of hourly backup, and they varied from a few to twelve.  For example, today there was a twelve plus hour gap from 12.53AM to 1.24PM when the computer was not being used.

I've maybe been lucky, but so far I've had no "failed" backups and have been able to find any file I looked for.  I've only needed to use a backup file once so far, but being curious I randomly check whether a change to an important file has been backed up.  So far, so good.

The wireless TM sure is handy when using a laptop as ones main computer.  

Dave

[Xairbusdriver]

I gave up on TM yesterday, not a single successful backup all day, manual or automatic. Decided to simply dump the whole backup which actually was empty back to March 8! That meant deleting almost 200,000 files which, if you've never done it, takes an enormous amount of time! I ended up using Onyx to delete the empty the trash.

TM has been running fine since the clean up/restart.

You're probably correct that it doesn't actually back up anything if there is no change in any file. But during normal usage, that would be rare. Even during non-human use (with certain apps running 24/7) there will probably be file changes. Assuming there is a period of time when absolutely nothing changes, I think TM will still need to check everything you have asked it to backup which may be where the most time/cpu use is, anyway.