How much space should I give Time Machine on the partitioned external drive?

[PicnicTutorials]

How much space should I give Time Machine on the partitioned external drive? I have 512G SSD internal on the imac.

I was originally thinking I just needed a 3T external drive. But now I have read it may be best to partition the drive and give a portion strictly to time machine. If I only need to give it 500G then I could get away with 3T drive. But if I should give it 1T then I would need to go to 4T drive.

Thanks!

 

[Ei kukaan]

The more you will give the longer history of files you will get. 2xSSD size will be OK.

 

[PicnicTutorials]

The more you will give the longer history of files you will get. 2xSSD size will be OK.

So right now I only use like 60G of my imac. How much space does each time machine backup use? So roughly how many continual backups would I get with 1T of space?

 

[Tomorrow]

In my experience, a lot of estimates for how much Time Machine space you need are overstated.

My iMac has a 1 Tb drive. I'm using a 1.5 Tb external drive, I have backups going back 3 1/2 years, and I'm using about 500 Gb of space on the external drive.

YMMV, of course.

 

[PicnicTutorials]

In my experience, a lot of estimates for how much Time Machine space you need are overstated.

My iMac has a 1 Tb drive. I'm using a 1.5 Tb external drive, I have backups going back 3 1/2 years, and I'm using about 500 Gb of space on the external drive.

YMMV, of course.

So each backup is just a couple Gigs then?

 

[Weaselboy]

So right now I only use like 60G of my imac. How much space does each time machine backup use? So roughly how many continual backups would I get with 1T of space?

You first backup will be slightly less than 60GB as TM does not backup certain cache and swap files. Subsequent backups will be small consisting only of new or changed files.

The size of your internal drive is only tangentially related to this. All that really matters is how much data you have or expect to have. So if you think all you will ever have is say 200GB of data, a 2x200 or 400GB partition would give you plenty of space for a full backup plus versions of your data.

So just estimate how much data you think you will have and make a partition 1.5 or 2X larger than that. Larger if you want to keep more/older versions of files.

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So each backup is just a couple Gigs then?

Not even that. If you just added a couple documents and maybe saved a new bookmark, then next backup can be as small as less then one megabyte.

 

[PicnicTutorials]

You first backup will be slightly less than 60GB as TM does not backup certain cache and swap files. Subsequent backups will be small consisting only of new or changed files.

The size of your internal drive is only tangentially related to this. All that really matters is how much data you have or expect to have. So if you think all you will ever have is say 200GB of data, a 2x200 or 400GB partition would give you plenty of space for a full backup plus versions of your data.

So just estimate how much data you think you will have and make a partition 1.5 or 2X larger than that. Larger if you want to keep more/older versions of files.

Thank you much sir!

 

[PicnicTutorials]

oops one more question. Is it nessisarry I partition the drive for time machine? Sorry for the stupid question but never partitioned a drive before. If partitioned will it show up as two drive icons on my mac? Or two folders within the drive? So say I don't partition it. If it runs out of space is there ever a chance time machine will erase my other files on the drive in order to make way for new backups? So I guess more than one question lol. Thanks!

 

[Tomorrow]

oops one more question. Is it nessisarry I partition the drive for time machine? Sorry for the stupid question but never partitioned a drive before. If partitioned will it show up as two drive icons on my mac? Or two folders within the drive? So say I don't partition it. If it runs out of space is there ever a chance time machine will erase my other files on the drive in order to make way for new backups? So I guess more than one question lol. Thanks!

If you plan to use the drive for Time Machine AND anything else simultaneously, you should partition the drive. Time Machine should reside on its own partition.

If you plan to use the drive ONLY for Time Machine, just format the drive without partitioning it.

 

[PicnicTutorials]

If you plan to use the drive for Time Machine AND anything else simultaneously, you should partition the drive. Time Machine should reside on its own partition.

If you plan to use the drive ONLY for Time Machine, just format the drive without partitioning it.

So I plan to use it for both. So partition it is. in that case...

If partitioned will it show up as two drive icons on my mac? Or two folders within the drive?

 

[Weaselboy]

So I plan to use it for both. So partition it is. in that case...

If partitioned will it show up as two drive icons on my mac? Or two folders within the drive?

It looks like two drives on your desktop. I have a 750GB external with a Backup and a Other partition and here is how it looks:

Disk Util

Finder

Desktop

Also a suggestion. Make the TM partition the first one so you can always non-destructively resize it later if you want. The second partition cannot be resized to be larger non-destructively.

 

[PicnicTutorials]

It looks like two drives on your desktop. I have a 750GB external with a Backup and a Other partition and here is how it looks:

Disk Util

Image

Finder

Image

Desktop

Image

Also a suggestion. Make the TM partition the first one so you can always non-destructively resize it later if you want. The second partition cannot be resized to be larger non-destructively.

Oh good tip thank you. Well I don't like that it shows up as two drives. Don't ask me why. Just makes more logical sense to me - one drive - one icon. In which case I need to ask... If I use the drive for time machine and my other files, why must (or should) I partition it? Thank you for humoring my obsessiveness.

 

[Weaselboy]

Oh good tip thank you. Well I don't like that it shows up as two drives. Don't ask me why. In which case I need to ask... If I use the drive for time machine and my other files, why must (or should) I partition it? Thank you for humoring my obsessiveness.

You don't really have to have two partitions. The idea of two is just so you don't accidentally copy something over top of your backup. Technically, there is nothing wrong with it.

You can just make one partition and use it for TM then just put a folder on the partition to use for your other files. It won't cause any issue.

If having those two icons on the desktop is bothering you, you can disable that in Finder preferences though.

 

[hfg]

If you use the disk for other storage, it is best to "contain" your TimeMachine space with a partition, otherwise TimeMachine will slowly gobble up all of the available space.

Keeping in mind that TimeMachine will not discard a single-copy file, even if old, without warning you, what is filling all the space is older versions of the same multiple files. Usually, really old versions of a file have no practical value to the user, who is probably more interested in the current version, or the last few recent updates. Therefore, a TimeMachine volume size would ideally be 1.5 to 2 times the size of the data-set you are backing up.

The first backup will be lengthy, but subsequent backups are usually short as they only handle changed files.

NOTE: If you have a Windows VM (Parallels or VMware Fusion), they are huge files which are modified each time you run them. You may want to mark them to be skipped under TM Options to avoid having a 30GB file backed up each hour!

 

[GovtLawyer]

Here's What I Did

I had used about 300 GB on my old iMac for Time Machine. Since my new iMac is almost exactly the same as the old, I partitioned a 2T drive to 850GB for Time Machine and 1.15 for files etc. It is easy for me in that it appears as two drives so I can always put new stuff in the right place.

My TM partition has used 362 and has 487GB left. I'm sure that will last me for quite a bit longer.

 

[colodane]

You probably won't need as much space on the Time Machine partition as you expect unless you make lots of BIG changes to your data over time. My iMac is about 2.5 years old, and I currently use a total of 56 GB on my main SSD. As others have correctly stated, the first Time Machine backup will use about as much storage as you have on your main drive, but subsequent ones will use a LOT less. In my case, my Time Machine drive has a total of 78 GB on it - only 22 extra GB after making new updates many times a day for 2.5 years. The incremental updates are quite small. I do not store movies or other exceptionally large files, but do have about 10 GB of music.