how much space does time machine require?

[Kristalghost]

hi I'm going to buy the new 15 inch mbp with a 500gb hd and its going to be my first mac.
I have a 500gb external hard drive that I'm am going to partition for time machine.
my question is now how much space do I reserve for time machine?
its because I have allot of data stored on my 2th external hard drive and id like to postpone buying a new external hard drive for as long as possible so being able to still put data on that hard drive would be a big plus.
what would be recommended as space reserved for backup?
and is there any way for me to exclude curtain maps because I do allot of transferring from laptop to external and to other computers so the files are on my computer very briefly and not worth the space on my backup disk.

 

[turkay]

Get a 1.5 or 2 TB SATA HD and connect it through a SATA to FW/USB2 docking station.

 

[McShizzel]

It depends how far you want to go back (a larger HD will allow you to go further back in time).

Time Machine drives fill up fast and yes you can exclude certain folders and files from being backed up by adding them to the exclusion list within the Time Machine preferences.

I would recommend having a dedicated drive for Time Machine of around 1 TB but if money is tight or you don't want to buy another HD right now then I'll suggest that you give Time Machine at least 320 GB of that 500 GB external.

One final thing, if you plan on backing up your Mac's HD and your 2nd HD (the one with a lot of stuff) to Time Machine then you'll need much more than 320 GB most likely.

 

[Kristalghost]

response

hmm interesting, I had a discussion a while back with a friend of mine.
Maybe you guy's can help out.
If I were to buy a new HD would you buy a firewire 800 or a network drive?
and is there much difference in cost?

 

[turkay]

hmm interesting, I had a discussion a while back with a friend of mine.
Maybe you guy's can help out.
If I were to buy a new HD would you buy a firewire 800 or a network drive?
and is there much difference in cost?

If that drive's gonna be for just backup purposes, even a FW400 should suit fine.

But i strongly recommend you to go for a dockable solution.

 

[mugtastic]

just a heads up from my experience. i used my 250gb ext fw drive to back up my 250gb macbook w/time machine with about 120gb on the drive at the time.

then i plugged in later when i wanted to backup (i don't need the constant backups time machine can do).

there was maybe 10gb more on the computer at the time and time machine wouldn't perform the backup. from what i read it requires double the free space to update the info. i'm back to super duper for back ups.

if i'm wrong about the space requirements i'd love to know, but from my experience get a drive twice as big as you will ever use.

 

[McShizzel]

With a Firewire 800 connection you'll get the benefit of having that speed for the backups which is especially useful for your first Time Machine backup since that usually takes a while after that most of the time backups are done quickly regardless of your connection/drive unless there's a huge change between backups for example you install GBs of new stuff.

A USB 2.0 connection is often enough although I'd prefer Firewire as for a network drive that's really up to you and is more for convenience then anything else although I don't know how long backups take through a network HD.

 

[mugtastic]

there was maybe 10gb more on the computer at the time and time machine wouldn't perform the backup. from what i read it requires double the free space to update the info. i'm back to super duper for back ups.

could someone confirm (or dispel) this info. does the time machine drive always have to have as much empty space as the drive it's backing up has used?

 

[JNB]

could someone confirm (or dispel) this info. does the time machine drive always have to have as much empty space as the drive it's backing up has used?

Well, only if you want to back it all up.

TM doesn't do any compression AFAIK, so you should have IMHO twice what is currently used. That should take you back several months of backups before it starts deleting the oldest stuff.

 

[mugtastic]

to clarify - my macbook had 100 gb on it. i used time machine once and backed up on a 250 gb ext. drive.

the next time i plugged it in there was less than 10gb more stuff on the macbook and time machine refused to do the backup because of lack of room on the ext. drive.

there was more than 100 gb free on the ext. drive!

so time machine can't incrementally back up a computer without as much free space as the total (mostly unused) size of the macbook's internal drive?

 

[Kristalghost]

doesn't it delete older backup's if there isn't any room?

 

[mugtastic]

yes it's supposed to. that's the thing.

it seems to me (and i could be wrong) that it needs as much free space as the total original hard drive is using, then proceeds to backup/manage/delete old stuff etc.

i know the 2x free space is needed for the initial backup, but it seems ridiculous to require that for incremental backups.

i hoped i had a setting wrong and someone will clarify.
then i'd try time machine again.