Time Machine HDD

Hello everyone,

I wanted to back-up my macbook using time machine. I already have an external Western Digital 160 GB HDD. It has most of my files, tv shows and stuff like that. When I connected it to back-up with time machine, it prompted me that the HDD would be first formatted and then backed-up. I had to cancel that since I can't afford to lose my files and stuff. I have heard macs usually don't as such have serious issues but since its better to be safe than sorry thats why I was wondering if I get a new HDD specially for time machine purposes, how much space would be sufficient enough for that?

Other than that, after how much time would you suggest me to back-up since I am a student so you can somewhat imagine the type of work I do. I'd really appreciate your help here.

Thank you.

Ideally the TM back-up drive should be larger than your Macbooks hard disk, so I have a 160 gig Macbook and my time Machine disk is 250 gig.

Once it is set up Time machine will back-up every hour, if you disconnect the drive it will just wait until the drive is connected again.

I try and do a back-up once a day

My macBook internal hard drive is 120GB and I have external 300GB (part of 1TB partition) for Time Machine and at times it says the back up disk is full and it deletes the previous back up file.

You asked "how much time would you suggest me to back-up". If you mean by that how long does it take to backup the drives, it could take a while for the first backup since all the drives you need backed up have to be transfered. If you mean "how far back should you have backups?" then you have to know that TM does incremental backups. That means after the first entire backup of the drives it only backs up what changes. If you add or change a lot of files on a regular basis you need more space to be able to recover from months back. TM keeps each hour for 24 hours, daily for a month , weekly for a month, and weekly before that.

I currently have 250HD on iMac, and a 320 external HD that i backup. they only have 400M used, i have 2 HD i use for TM that i switch between every week or so. I lost a drive many years ago, so i like to have one backup offline at all times. One is a 500mb and the other is a 750mb. I am thinking of buying a 1tb raid to replace them, so I won't have to switch.

Thanks a lot guys for your help and support. Just one more question.

If we have an external HDD for time machine, can we use that for other purposes as well or should it only be used for TM purposes?

You can use the external for anything you want in conjunction with TM. TimeMachine creates it's own file image (sparse bundle) that won't interfere with anything. Just keep in mind that the more tasks/data you keep using for the drive the more space you will reduce to use for TM.

As a general rule I give TM a complete drive (or at the very least a complete partition) and do not use it for anything else (movies, music etc0.

Oh alright.

Thank you

I just bought an external HD for my macbook. It required to be formatted first use, which was fine, now I just plug it in every few days when I have updated images or software to back up. Its great!

Oh alright.

Thanks for sharing that piece of information