Does time machine compress data

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Hi all,

Perhaps a stupid question but I have a 1TB drive on my imac and am wondering which size drive to buy as a backup for time machine as I am unsure if it compresses the data or makes an exact copy?

Thank you :)
 
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Oh and a related question if I may, with multiple user accounts on the mac will everyone be able to access all of the data copied by time machine or can it be restricted?

Thanks again
 
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Hi. I would go for a bare minumum 1.5TB drive as a Time Machine back up for your system, as it will give plenty of room for several back ups, rather than just one (assuming you eventually fill your internal to that level). It does not compress data at all, it is like for like.
As for the other question, if they only have access to their own account, then they shouldn't see the TM back up if it's not part of their system folder.
 
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Thank you very much! :)
 

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But note: Time Machine will not backup except when you are logged in to the account that has TM set up.
 
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But note: Time Machine will not backup except when you are logged in to the account that has TM set up.

Oh yeah, forgot to mention that, nice pick up Bob, Thanks.
 
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Thanks guys I really appreciate the advice!
 
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Hi all,

Perhaps a stupid question but I have a 1TB drive on my imac and am wondering which size drive to buy as a backup for time machine as I am unsure if it compresses the data or makes an exact copy?

Thank you :)

It does not compress data. It uses a "sparse disk image" which does not save free space, so you do get a tiny amount of savings, but basically the answer to your question is no, it does not compress data.


Oh and a related question if I may, with multiple user accounts on the mac will everyone be able to access all of the data copied by time machine or can it be restricted?

Thanks again

Users should be only able to access TM data that pertains to their account.
 

bobtomay

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Users should be only able to access TM data that pertains to their account.

This one I don't know about. I know I can browse through my wife's TM backup from my machine. The TM backups are not encrypted. Have never checked from her computer to see if she can browse mine, but I'll bet she can.

I'll do a couple of tests and post back.
 
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Thanks again guys, the reason for me asking about the other users is I am a photographer and some of the images I shoot are not child friendly so I don't want the kids stumbling on them if they click on the drive.

I know that when I have a normal drive connected it's accessible on any account, I thought perhaps the TM backup may be different but if it's not there's no point in having separate private accounts.
 

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I use a Time Capsule for my TM backups. The other user accounts on my machine cannot access that hard drive at all. The TC is set up as a password protected server and without the password, no other account has access.

Sorry, can't test it on a external drive connected directly to my Mac as I use that for bootable clone backups rather than TM.

My wife's MB also does TM backups to the same TC. She can enter her own Time Machine backup, but her computer also does not have the required password to connect to the TC in Finder and cannot browse that drive.

All I can suggest is experiment. Do a TM backup, log into another account and see if you can browse it from there. If so, a Time Capsule might be worth the investment in your situation, just for the simple access control it provides preventing other accounts/users from accessing the drive.

I can tell you, I have full access for browsing my wife's TM backup in Finder. But then, I have the password to the drive.
 
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Thank you bobtomay, that's very helpful and very much appreciated!
 

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One other note just so it's clear if you decide to go the TC route - the other user accounts on my machine and my wife's MB do use the wifi network on the TC but have no access to browse the drive there as these are two separate passwords.

You are probably already set up with a router. You would not need to replace it with a TC. I use a D-Link router which is the one connected to the modem and handles all the DHCP in the house. The TC is set up in bridge mode connected via ethernet to the D-Link at the opposite side of the house. I run two wifi networks, one from the D-Link and a 2nd on the TC. Makes for easy switching between networks as I move around inside and outside the house with my mobile devices. One network is set up as a combo g/n for the devices that don't have n capability and one network is n only.
 

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