External Back Up Capacity

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Hi guys,
Apologies for asking a question that is probably already covered however I am switching from Windows and unsure of the answer despite reading loads!

I have a 750Gb MacBook Pro with about 250Gb of music, photos and documents that grows in small increments weekly.

What size external back up should I use? I am going to use TimeMachine and CarbonCopyCloner to ensure I don't lose anything should the worst happen.

My understanding is I need 2x the size of my drive for TM and 1x for CCC - so I need a 3TB external drive. Is this right?

Or will a 2Tb drive be sufficient?

Thanks in advance!
 
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I'd say a 2TB external would be sufficient.
 
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Time Machine will leave a history of backups on your external drive. When it runs out of space, it deletes the oldest backup. So, the answer to your size question depends on how many backups you want to keep around. TM will backup once per hour by default. You can get an "add-on" application to change that, but cannot change it within TM itself. I have mine set to do backups while I'm having dinner. TM will slow everything down while it is running a backup. With that much to do (750MB) I don't know if it would finish in an hour, so without a scheduler, you'd be backing up all the time, and always feel a drag on performance.
 
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Hi,
Thanks for the comments so far - as I mentioned, I am new to Macs to I really appreciate it.

Initially I think it'll only have about 200Gb to back up so shouldn't take too long. However, it is for a MacBook and I'll probably only back up once a week unless I have done a significant piece of work/added a significant amount of music/photos etc.

I presume CCC take up exactly the same space as the size of my hard drive - any ideas how much space TM takes up if it is backing up 200Gb of files? Does it compress them or just make copies of them?

Does TM only make new copies of the files with recent changes?
 
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MacInWin

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What toMACsh said is true, but after the first TM backup, it only backs up what changed since the last backup. So if you have little change, the incrementals are really small and quick. I use TimeMachineEditor to set TM to backup twice a day, noon and midnight. CCC is set to backup once a day, just after midnight.
 
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By default, TimeMachine does not compress files. A full (initial) backup with either TM or CCC will take about as much space as the files take on your internal HD. If you have 250GB of space being used on your HD, the CCC and TM backups will be ~250GB each, using ~500GB of your external. As time goes by, TM will add to its space usage with its incremental backups. The CCC backup will continue to take about as much space as the the files on the internal HD.
 
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chas_m

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Putting all your (backup) eggs in one basket seems to me like a bad idea. What if the backup drive fails -- now both your TM *and* clone backups are gone.

I recommend using different external drives for the Time Machine backup and the clone backup.
 
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J
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That is actually something I hadn't thought of. Worryingly!

Would you suggest a couple of 1Tb drives then?
 
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chas_m

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Yes, that should do. The 2x suggestion for TM is likely overkill, based on how insanely cheap hard drives are these days.

Cheers
Chas
 
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J
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Great and thanks.

Has any one had use of the WD or LaCie brands sold on the Apple store? Seem to have good reviews everywhere but even so I am more of a recommendation man.

Worth getting a couple of those? Can probably source them from cheaper elsewhere but more concerned with the reliability.
 
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My opinion is that worrying about a backup drive failing, as in the above scenario, is a bit unwarranted. If the external drive fails, you just get another one. As long as you do so quickly, there would be no problem. The chances of the internal and backup drives failing at the same time is probably 1 in several billion. But what increases the odds dramatically is some catastrophic event, like a house fire. If you want to put some of your worrying brain cells to work on something, use them for that scenario, not for one where you have your computer and multiple different backup mediums all sitting inches apart in the same location.
 
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J
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Another valid point. I do like a good discussion. I presume TM and CCC would let me know if the back ups had failed for any reason?
I also presume that a 2TB external drive will cost significantly less than buying two 1TB drives which would make things financially easier.
 
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MacInWin

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As one who has, in fact, suffered from a double drive failure (Internal HD and backup drives), I would agree with chas_m on this wholeheartedly. What saved me that time was I had a third drive with a clone of my system on it.

I have TM on one external drive and CCC making clones to a different external drive. The concerns raised by ron4mac are also pertinent, and I do have an off-site storage for the most critical stuff. Basically the off-site is just a USB memory stick with the "business" stuff of accounts, passwords for financial accounts, family pictures, etc. I refresh it every few months. Nothing magic in the off-site storage, I just give the stick to my daughter, who lives about an hour away. It's more for a "what if something happens to me" backup, but if there was a catastrophe that destroyed all my hardware here, I'd have the essentials to keep going there. I also use the cloud for storing passwords through 1Password and the syncing it does through Dropbox and iCloud.

The idea is NOT to put all your eggs in one basket, to spread out the risk.
 
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More salient points - thanks. The more information I have, the better informed my decision is - rightly or wrongly!

Don't get me started on 1Password - that is my next project!
 
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1Password

Hi there JesmondJester, this is the 1st time I've ever made a reply, or any comment, other than ask questions that I felt I should already know the answer too, I have been helped countless times and not just on this site, (which is *Great*). Anyway more to the point, I am as thick as 2 short planks, so I tried 1Password based on the reviews, (forewarned is forearmed ). I had a series of strokes and was forgetting everything I needed to remember. 1Password in my view, and I stress, only my view, based on using it, (now 1Password4) and I've forgotten for how long. It has never let me down. It's not just passwords it will fill all forms for you, and I feel it's very safe and secure, I've never had a problem with security issues while using 1Password4. There is an identity section which is great, you can keep your Passport, Driving licence, cards info. N.I No, anything at all it's super. I am aware My iMac could get hacked. If I'm buying over the phone, in 3 sec's, I have all I need on screen, without having to squint to read the small stuff, (my eyes have followed my cognitive reasoning in a downward spiral). Anyway I suggest you get it, and if I'm ever proved wrong about it, tell me and I'll commit Hari-Kari with a rusty bread knife. Cheers for now, and thanks to those that have helped me in the past, and I'm sure I'll need to pick someones brains in the future. TTFN. Ron :)
 
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JJ...you asked about brands of ext hdds. I highly recommend WD just because I have had great experince with WD in the past. I currently have 2...one for TM and the other with my CCC. As chas_m suggests...use separate ext hdds. I use a Firewire 800 WD for my CCC backup since it is bootable and runs just a bit slower than the internal hdd. The WD I use for my TM backup is USB 2.0 and that is good enough.
Probably all ext hdd's come with some kind of manufacturer's software that is not required for operation and is optional to install...my advice is...DON"T!
 
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Hi DB & JJ, listen to the man JJ, he's spot on, I currently use 2 My Passport for Mac USB3 2TB each, I got those because long ago I read from the lads & lassies on here that WD were about the best and the way to go. I've never had one fail me...(YET)... That's it, nuff said. TTFN Ron :)
 

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