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How to back up a Mac: Four types of backup all Mac users should be using

David Fanning | March 8, 2016
What's the best and most secure method of backing up a Mac?

What's the best and most secure method of backing up a Mac?

Mac users would be forgiven for forgetting about backup. Hard disk technology means they are bigger, faster, cheaper and more reliable than ever before; and if you haven't had a failure lately, it's easy to become complacent. But there's nothing like a catastrophic failure of your storage to concentrate the mind on backup.

Anybody feeling safe because they are using the latest technology may find their faith may be misplaced. For example, many laptops now use SSDs. Solid State Drives are super fast, and getting cheaper by the day. So they are a popular option in laptops, and the MacBook Air insists you use one. But as much as SSDs act like HDDs, they are not disks, and have their own inherent volatility - so if anything does go wrong with an SSD, it is far more likely to lose all the data than an HDD. 

This is part of a series of articles that should help you in the event of data loss.

Why failed SSDs can be a data-loss nightmare

Despite being incredibly resilient to being dropped or run over, SSDs can still suffer similar problems to the ones you might expect on an HDD. But things that are relatively simple to fix with an HDD simply aren't possible with an SSD. When files are deleted on an HDD, they aren't really deleted; there is a directory that keeps track of what files live where. Instead of going to the file and setting each block to zero it just tells the directory the file isn't there. That means the blocks where the file lives can be over written. So long as you haven't overwritten those files, they are retrievable with data recovery software.

SSDs on the other hand, are handled differently. Unlike HDD blocks, SSD cells can't be overwritten, they must be empty before they can store data. So SSDs use a system to manage empty cells, and erase cells that are available to record data. If they didn't use that system, they would quickly become very slow.

With an HDD, so long as the disk is still spinning, and the read head is still controllable, there's still a good chance data recovery software will be able to retrieve some data. With an SSD, if the operating system has lost track of files, either through deletion of through other problems, the data that once lived in those cells will be erased forever.

Disk Utilities don't work on SSDs

Disk utilities don't work the same way on SSDs. In fact they don't work at all for SSD data recovery. So if you had, in the back of your mind, a thought that you might be able to retrieve data from a failed SSD, think again - because you can't. Which is a very scary thought.


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