Time Machine

I'm thinking of buying an external drive for time machine back-up.
1.What specs should I look for? Ie., how big a memory , formats etc etc?
2. I have a MacBook Pro and a MacBook Air. Can I use the same external drive for both computers?
thanks

Hi.

1. My personal rule of thumb is to buy the maximum computer you can afford, with priorities to RAM and disk space.

2. Yes. Just make sure you buy a disk big enough to handle that kind of load. I prefer my backup disk to be at least 2X the size of the source drive. So, in your case, you'll want to make sure it's at least 2X the aggregate size of your source drives, plural.

Good luck,

Z

question #2 it is preferable to use one machine for one external drive for time machine.

Depending on how much your budget is, I would recommend the following:
1. 1 drive for each machine. Label them so you don't get them mixed up.
2. Each drive being at least 2x the size of the drive you are backing up.

The drives will fill up eventually. before it does, Time Machine will notify you that it will be writing over the oldest backup files. I just had a 1TB drive flip for my 500gb MBP drive. No biggie, I let it continue on.

Now, if you want to use a drive that will be connected to a network and give you plenty of room, I would look into a Western Digital My Book Live. It will plug into your router and can be used for multiple Time Machine backups. I have a friend who has one for 3 machines, with the drive set up with 3 partitions of 1 TB each. This is done on the drive, not the computer - do not let the Mac format the drive. The drive has a web interface to configure it. I have one of these drives, but do not use it for Time Machine, I use it for network storage with 4 different shares set up. You could get the 3TB model, set up 2 1TB paritions for your MacBooks' TM's and still have 1TB for network storage. The problem with this is that if the WD drive goes bad, you lose EVERYTHING in one shot.

I still recommend 1 and 2 that I mentioned at the start of the message.

Budget - is key - but remember that your backup is still a point of failure if you only have one. Consider getting a raid system with at least mirroring so that you have a chance if one of the drives fails. Right now I have my backups on a Time capsule and an external hard disk I keep at work - so it doesn't have to be RAID. I do this because my original Time Capsule died (Luckily the hard drive was OK and I was able to put that into an enclosure and still have all my backups) but that taught me that if you only have 1 drive for backups - and that drive goes - you are toast.

EDIT:I am echoing what Deckyon said - but that single point of failure is a very important message.

Lacie makes some raid boxes that have worked pretty well for a friend of mine.
LaCie is the premier manufacturer of high quality digital storage.

If you want low hassles the Time Capsule is a good wifi/router that works with everything Apple. I back up multiple computers to my TC.

Synology is another one - but I haven't bought anything from them yet. They do support AFP for network backups and raid on the box itself.
Synology Network Attached Storage - NEW NAS Experience

If you are going with just external USB I like seagate - I have external drives from them from 2005 still working. YMMV. I have bought several Western Digital external drives and they have been working since 2007 ro so. YMMV again.

I do like the Seagate goflex system where you can change out the interface to the drive. I bought a firewire cable which works well. They now make a thunderbolt interface but it is expensive. Also - the thunderbolt is single so you can't daisy chain the drive.

The next backup drive I buy (just to consolidate some of my other backup drives really) will be put in a FW800 case. I figure that will hold me even when I move to a machine with TB because adapters will be relatively cheap and FW800 is still quite swift.

ok question about back-up, me and my wife both have MBP 750gb each, we have had our systems since January of this year. I havent backed these up yet and I am wanting to do this, is there anything I should do to prepare them before I run Time Machine on these systems?

No, you don't need to do anything. Just plug in an external drive, it will ask if you want to use the drive for Time Machine, you say yes. I recommend leaving it alone during the first backup, since that will take a long time. After that it just does its thing for a few seconds every hour. It's as no-brainer as it gets (though for some reason people DO seem to enjoy making the process as complicated as possible!).

Thank you all, guys!! All your suggestions very helpful.