Resolved Why Time Machine backs-up so much when nothing has changed?

[Akarin]

Hi all,

I have a little question regarding time machine (and yes, I am new to Mac). I noticed that every hour, it does its back-up on my external 1TB drive but... ...when nothing has changed (and I mean nothing as I was not using it), it still backs-up about 15GB of files. Why is that? Isn't it a differential back-up based on filesystem that would just copy the new/updated files?

Thank you for your answers.

 

[r.j.s]

Are you not using the computer at all?

Do you have a virtual machine running during that time?

 

[AcesHigh87]

It make sense for TM to run a backup even when nothing has been done, it's scheduled to do so. Something does seem up though if it's backing up that much. 15GB is a huge backup for me even when I have been using my mac. If it I haven't been the backup is usually only a few MB.

 

[Akarin]

Are you not using the computer at all?

Do you have a virtual machine running during that time?

Nope. Nothing.

It make sense for TM to run a backup even when nothing has been done, it's scheduled to do so. Something does seem up though if it's backing up that much. 15GB is a huge backup for me even when I have been using my mac. If it I haven't been the backup is usually only a few MB.

Not doing anything at all. For example, I left it on this night, did nothing, nothing running, no downloads in progress and I manually backed it up before going to bed. This morning, I log in (it was still on), I click on "back up now" on the Time Machine icon in the status bar at the top and bam : copies 15GB. Is it strange?

 

[ctucci]

Nope. Nothing.

Not doing anything at all. For example, I left it on this night, did nothing, nothing running, no downloads in progress and I manually backed it up before going to bed. This morning, I log in (it was still on), I click on "back up now" on the Time Machine icon in the status bar at the top and bam : copies 15GB. Is it strange?

Same here, but I do run a VM. I've always assumed TM had detected changes in that big VM file.

I don't suppose it could be something like the equivalent of a large email database file ( like the one outlook 2011 for mac uses )? Something that could change frequently enough just by normal automatic email program checking?

 

[Akarin]

Same here, but I do run a VM. I've always assumed TM had detected changes in that big VM file.

I don't suppose it could be something like the equivalent of a large email database file ( like the one outlook 2011 for mac uses )? Something that could change frequently enough just by normal automatic email program checking?

It's exactly that ! My Outlook 2011 db is about 15GB and I have tested this:

- manual back-up with Outlook closed: ±1MB
- manual back-up after receiving ONE mail in Outlook: ±13GB

I wouldn't have thought of that but you nailed it. Thanks for that. It is not a problem as I don't mind my external drive running and copying, I only use it for back-ups but I wanted to know why

 

[ctucci]

It's exactly that ! My Outlook 2011 db is about 15GB and I have tested this:

- manual back-up with Outlook closed: ±1MB
- manual back-up after receiving ONE mail in Outlook: ±13GB

I wouldn't have thought of that but you nailed it. Thanks for that. It is not a problem as I don't mind my external drive running and copying, I only use it for back-ups but I wanted to know why

Glad to contribute!

 

[AcesHigh87]

Glad you figured that out. I would say exclude wherever that is saved or, better yet, just use the mac mail application. works better and doesn't have that problem.

 

[garycurtis]

I have the same question. With little activity, backups to TM over a Firewire 400 cable take nearly 1/2 hour.

Most of my email is Google mail, so that's in the Cloud. But I have Apple Mail (OS 10.5.8). Which are the data files there to exclude (including the complete path)?

Thanks