Time Machine - Storage

Hi, where does Time Machine store it's files. Am i right in saying there is a copy on the local disk and then a back up on the designated external drive.

I understand that when i plug my external drive in, Time Machine copies files to it BUT

01 - does Time Machine have some sort of other copy / back up of my files on my local machine too... for instance, if i do not have my external drive plugged in and i want to re-call a deleted file from last week, i can do this through Time Machine... so where is it getting the file from, as it cannot locate it from my external drive...

02 - how do the backups differ between what is copied to my external drive and what TM accesses on my local disk when retrieving a previous file... are both backups the exact same and are the files transferred to my external drive just an update of the local backup copy...

03 - if the system keeps a backup of all of the files on the local disk... how does it not eat up my hard drive...

Thanks in advance to anyone who can explain any of the above as i am completely confused

Normally Time Machine stores its files on the external drive. Under Lion if Time Machine cannot find your chosen external drive it will store its backup files on your main (boot) drive until you reconnect the external drive.Earlier versions of Time Machine did not behave this way and it can be turned off. If Time Machine is backing up to your local (internal) drive and the space is needed some of the backup may be deleted.

I think these two articles will answer most of your questions:

OS X Lion: About Time Machine's "local snapshots" on portable Macs
OS X Lion: Time Machine overview

01 & 02
-- Open time machine then you'll see pink and white lines. PINKS are from External, WHITES are from Internal (local snapshots). Both will backup at the same time so when you remove your External you still have the whites available. When external is connected again, time machine will back-up by copying the whites into your external. This time Pinks and Whites are available again. Whites will be only up to one week and it'll be deleted (as I recall, not sure). Hope this did not confuse you.

03
-- Yes it will eat up a little bit but very negligible. If your internal HD is running out of space it'll will delete by itself. Mine, I disable it. Local snapshots can be disabled using Terminal command. if you're interested I can give you the command.

CebuCity said:

01 & 02
-- Open time machine then you'll see pink and white lines. PINKS are from External, WHITES are from Internal (local snapshots). Both will backup at the same time so when you remove your External you still have the whites available. When external is connected again, time machine will back-up by copying the whites into your external. This time Pinks and Whites are available again. Whites will be only up to one week and it'll be deleted (as I recall, not sure). Hope this did not confuse you.

03
-- Yes it will eat up a little bit but very negligible. If your internal HD is running out of space it'll will delete by itself. Mine, I disable it. Local snapshots can be disabled using Terminal command. if you're interested I can give you the command.

Click to expand...

Hi, thanks for your reply... if it is disabled locally... I presume that the external drive will need to be plugged in in order to retrieve a previous files... can you give me the command please

This should get you going in the right direction. It covers restoration and a few other basic. Thought posted it earlier sorry Mac 101: Time Machine

oo7ml said:

Hi, thanks for your reply... if it is disabled locally... I presume that the external drive will need to be plugged in in order to retrieve a previous files... can you give me the command please

Click to expand...

Exactly. You can try it. Once you disabled the local snapshots then you open time machine with external removed, you can't get into the backup files.
Disable time machine local snapshots
All about local snapshots