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What size drive for Time Machine?

ifman

ifman

macrumors member
Original poster
Mar 30, 2011
52
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I just bought the Seagate 4TB backup drive for my new imac (27" 5K with 2TB). I only have about 500gb on the computer, which I transferred from my old PC. I'm retired, so I won't generate a lot of work files, but I do want to scan and digitize all the old family photos....I guess that may take some space.

My question is....Will I want TimeMachine to use the full 4TB of the Seagate to make backups, or should I reformat the Seagate and partition so I can use 1 or 2 TB for regular file storage? In other words, do I need 4TB for endless TimeMachine backups.....or less? What is the normal setup?
 
the general rule is, double the size of the volume being backed up. this gives TimeMachine room to hold version history and deleted files as well as perform it's tasks. TimeMachine will just keep filling up the available space and dump the oldest versions as the drive fills up.

question, if you have over a TB available on your main drive maybe just put your files there (and TimeMachine will keep the backed up). and, if you use part of your TimeMachine drive for general storage, where are those files backed up to? I'd leave a TimeMachine drive dedicated to just that task and get other drives if you need work or dump space.
 
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ifman said:
In other words, do I need 4TB for endless TimeMachine backups.....or less?
Click to expand...

No you do not. Most people suggest 2X the amount of data you have, so if you have around 500GB of data, a 1TB partition would leave you plenty of room for Time Machine versioning. Then you can use the other partition(s) for whatever you want.

The only issue with that is if you have vital data on that second partition, it is not really being backed up anywhere since the Time Machine data is on the same physical drive. If you don't mind that, there is no problem making and using partitions.
 
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Another option is to use a caddy and hdd dedicated to the Imac. Beauty of the caddy is that you can use either 2.5 or 3.5 hdd which alot of people have just lying around. It's a good and inexpensive way of using redundant hdd.
 
Time machine will eventually fill any size drive given enough time.

Currently I have 623gb used on my iMac. My TM backup is 686. This dates back to March 22, 2016. So a 63 gb delta over ~8 months with my particular usage.

I'm generally careful to keep my scratch work in a non backed up folder so I don't inadvertently fill up the time machine.

Since I'm using a NAS I can add terabytes to my TM with a few clicks should it fill up. Highly recommend using a NAS for this and other various reasons (data redundancy).
 
An SSD is kind of a waste for a backup drive. Better to spend that money on multiple back drives that can be swapped.

Anything that is on the same drive as your backups is by definition at risk. If your backup drive fails you also lose anything on any other partition.

Best to have backup drives being single use items. Better to have a second one and swap out occasionally. Keep one at office/family members home/safety deposit box as a disaster recovery. If you house burns down or thief breaks in and takes both system and attached drives.
 
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afctee said:
...you actually just gave me an idea. I have a 3TB SSD for my Time Machine. I might partition it, and then run my VMWare VMs, from there...
Click to expand...
Where will you back up your VMs from?

As for using SSDs for backing up, I'd not use them for that purpose
 
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afctee said:
Oops, good point about VM backups...!
Back to the drawing board, leaving all as is
Click to expand...
I back up my VMs outside of TimeMachine because they can clog up your backups, because as you use the VM, they'll be flagged for backup, every hour. I exclude them, and them and back them up on a different volume.
 
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