Time machine backup multiple Macs to the same external storage

[s2s]

A little bit confused, to backup multiple Macs to the same external SSD, do I need to partition the SSD to multiple APFS volumes first? Or a single APFS volumes will host multiple time machine backups?

Must the size of external SSD be same or greater than total hard disk size of all Macs? 3 Macs for example, with disk size of 512GB, 256GB, 256GB, each uses less then 50%, do I need a 1TB SSD to initiate TM backup for all 3 Macs?

 

[chabig]

I don't think you need to partition, but do create multiple volumes, one for each Mac. This works because APFS can have multiple volumes in one partition, all sharing the same space. What you think of as a partition, is now called a container, and they are fixed size. This article explains it pretty well:

Should you add a new APFS Container or Volume?

Adding volumes in APFS is quick and simple. But why would you ever want to add a container to a disk? An exploration of their differences, and when containers are useful.

eclecticlight.co

 

[bernuli]

A little bit confused, to backup multiple Macs to the same external SSD, do I need to partition the SSD to multiple APFS volumes first? Or a single APFS volumes will host multiple time machine backups?

Must the size of external SSD be same or greater than total hard disk size of all Macs? 3 Macs for example, with disk size of 512GB, 256GB, 256GB, each uses less then 50%, do I need a 1TB SSD to initiate TM backup for all 3 Macs?

I don't think you need to partition. 1 HFS+ volume will do it. I have not yet tried Time Machine with APFS targets. 1 TB should work for what you are doing but I recommend 2TB so you can have a little history.

 

[s2s]

I don't think you need to partition. 1 HFS+ volume will do it. I have not yet tried Time Machine with APFS targets. 1 TB should work for what you are doing but I recommend 2TB so you can have a little history.

I know single volume works with HFS+, but I am trying to make use of advantages of APFS.

 

[s2s]

I don't think you need to partition, but do create multiple volumes, one for each Mac. This works because APFS can have multiple volumes in one partition, all sharing the same space. What you think of as a partition, is now called a container, and they are fixed size. This article explains it pretty well:

Should you add a new APFS Container or Volume?

Adding volumes in APFS is quick and simple. But why would you ever want to add a container to a disk? An exploration of their differences, and when containers are useful.

eclecticlight.co

Thanks, it is a great article. Sounds like I don't need to create partition (container) unless I want to make 3 bootable volumes in the same SSD, which looks cool, but not necessary to me as it won't take much time by Internet Recovery, all I need is data recovery).

 

[gilby101]

Thanks, it is a great article. Sounds like I don't need to create partition (container) unless I want to make 3 bootable volumes in the same SSD, which looks cool, but not necessary to me as it won't take much time by Internet Recovery, all I need is data recovery).

Time Machine backups are no longer bootable volumes. The backups only contain the -Data volume and not the read only system volume.

This decision by Apple will be the cause of frustration to those with slow (or no) Internet connection. I really think this strengthens to case for using other backup products (e.g. CCC) in place of or as well as TM [I have not done this yet].

Personally I will be keeping an external small SSD with a current working version of BS along with a copy of the BS installation app and some diagnostic tools.

 

[s2s]

Time Machine backups are no longer bootable volumes. The backups only contain the -Data volume and not the read only system volume.

This decision by Apple will be the cause of frustration to those with slow (or no) Internet connection. I really think this strengthens to case for using other backup products (e.g. CCC) in place of or as well as TM [I have not done this yet].

Personally I will be keeping an external small SSD with a current working version of BS along with a copy of the BS installation app and some diagnostic tools.

Yeah just read this in the other thread here... it won't affect my use case but I am sure many others will get frustrated by this change.

 

[dcmaccam]

Time Machine backups are no longer bootable volumes. The backups only contain the -Data volume and not the read only system volume.

This decision by Apple will be the cause of frustration to those with slow (or no) Internet connection. I really think this strengthens to case for using other backup products (e.g. CCC) in place of or as well as TM [I have not done this yet].

Personally I will be keeping an external small SSD with a current working version of BS along with a copy of the BS installation app and some diagnostic tools.

Hi, So am I correct in thinking if I totally wiped my drive in the machine I would need to do an internet recovery to get a bare system and then use Time Machine to replace my data. If I just want to replace my system to a previous date I just use Time Machine as normal and it will only erase and restore my data.

 

[gilby101]

So am I correct in thinking if I totally wiped my drive in the machine I would need to do an internet recovery to get a bare system and then use Time Machine to replace my data. If I just want to replace my system to a previous date I just use Time Machine as normal and it will only erase and restore my data.

Yes. And recovering all your data includes applications and settings.

 

[HDFan]

disk size of 512GB, 256GB, 256GB, each uses less then 50%, do I need a 1TB SSD to initiate TM backup for all 3 Macs?

You need a minimum of 2x the size of your source. Assuming at some point you fill all those disks that would be 2 TB minimum.

1. TM often way over estimates the amount of space that it will need and backups will fail if you don't have enough space.

2. If you have a lot of churn there is going to be a lot of history and you will need more.

3. When you run out of space TM will start deleting backups. The more space you have, the longer TM will have historical backups. I use a 6 TB drive backing up maybe 3 TB. Since I have plenty of extra space I have backups from May 2020. Actually I would have even earlier ones but I had to keep starting TM from scratch every few months as I was filling up the disks, discarding backups. Looking at the backups via Daisydisk I realized that I was backing up terabytes of IOS backups (~/Library/Application Support/Mobilesync directory) and disk protection (TechTool Protection). Just added them to the exclusions so we'll see how it goes.

4. An SSD for TM backups is a waste of money. A hard disk (assuming you aren't in an enviroment where an SSD would be indicated) is a far better use of your money. You can get a much larger hard disk for the same money as a small SSD giving you much more history. The initial backup will be slower, but incrementals will be relatively fast. Since it runs in the background the time to run a backup normally is not interesting.

5. Make sure you have a 3-2-1 backup strategy, where TM is only 1 of the 3 backups. TM backups get corrupted. Ideally one should be a clone, made by Carbon Copy cloner or its equivalent. If you have a failure a restore from a cloned drive is way faster than from TM.

 

[gilby101]

Make sure you have a 3-2-1 backup strategy, where TM is only 1 of the 3 backups.

3-2-1 strategy is: 3 copies of your data, 2 of which are local, and 1 off-site.
The two local being the source data and a backup usually to NAS or DAS. The off-site can either be a physical disk or stored in the cloud.

 

[.max]

do I need to partition the SSD to multiple APFS volumes first? Or a single APFS volumes will host multiple time machine backups?

macOS will do this for you. When you try to backup to an APFS Time Machine with existing backup from a different Mac, it will ask if you:

• Inherit existing backup (that is when you migrate to a new Mac and will no longer need to restore to the old one)
• Start new backup (when you want backups for two independent Macs)

The second option will create a new APFS volume.

I’ve had the same question and stumbled on this thread.

 

[BulldogMac]

Would the answer and approach be any different on Mojave or Catalina? Thanks

 

[gilby101]

Would the answer and approach be any different on Mojave or Catalina?

Yes. Mojave and Catalina do not use APFS format on TM destination, rather HFS+. But using a share for TM destination is much the same.

 

[hariv]

A little bit confused, to backup multiple Macs to the same external SSD, do I need to partition the SSD to multiple APFS volumes first? Or a single APFS volumes will host multiple time machine backups?

Must the size of external SSD be same or greater than total hard disk size of all Macs? 3 Macs for example, with disk size of 512GB, 256GB, 256GB, each uses less then 50%, do I need a 1TB SSD to initiate TM backup for all 3 Macs?

I would like to backup internal iMac. to a external time machine volume A and then external SSD drive to a different volume B to the same time machine drive. so that I can keep backup of internal SDD and another external drive backup separate .
how can this be done ? any idea.
I am not able to setup this option in timemachine.
It can backup two different drives , but not seen an option for the above.

 

[bernuli]

I would like to backup internal iMac. to a external time machine volume A and then external SSD drive to a different volume B to the same time machine drive. so that I can keep backup of internal SDD and another external drive backup separate .
how can this be done ? any idea.
I am not able to setup this option in timemachine.
It can backup two different drives , but not seen an option for the above.

I don’t think possible without manual intervention before each backup. Which is not something I would suggest

 

[KenMDT]

Hi everyone - Loooong time listener, 1st time caller. Thank you all for such great information. My question is a little more complicated and probably moronic if I'm being honest.

I have an older MacBook Pro (2013) running High Sierra that I need to keep running HS for some platform things I can't upgrade and continue to use.

I have a newer MBPro (2019) running Big Sur

I have an older iMac (2014? I think) running Catalina. I haven't upgraded it to Big Sur, but don't think it'll be a problem. At the time it was the most beefed up iMac I could possibly buy with i7 max cpu & 32gb ram. It's still a great workhorse for us.

I would like to be able to use a single 8TB External Drive as the 1st level Backup for all 3 machines but currently they're all running 3 different OSX's - is that a problem? Can I still do the same thing using a single drive I already have?

Thanks in advance for your help!

 

[bernuli]

That should work but I have not tried it so can’t say for sure.

you definitely want all on one drive? If were me I’d buy a separate portable USB drive for each machine. Then use the 8TB drive for CCC images of all machines

 

[dcmaccam]

Hi everyone - Loooong time listener, 1st time caller. Thank you all for such great information. My question is a little more complicated and probably moronic if I'm being honest.

I have an older MacBook Pro (2013) running High Sierra that I need to keep running HS for some platform things I can't upgrade and continue to use.

I have a newer MBPro (2019) running Big Sur

I have an older iMac (2014? I think) running Catalina. I haven't upgraded it to Big Sur, but don't think it'll be a problem. At the time it was the most beefed up iMac I could possibly buy with i7 max cpu & 32gb ram. It's still a great workhorse for us.

I would like to be able to use a single 8TB External Drive as the 1st level Backup for all 3 machines but currently they're all running 3 different OSX's - is that a problem? Can I still do the same thing using a single drive I already have?

Thanks in advance for your help!

I have backed up 2 different machines to one drive using Time Machine, but now I use an external drive on each. This is due to the fact I had to unplug and replug the drive. So I found it better to use single drives.

 

[gilby101]

I have an older MacBook Pro (2013) running High Sierra that I need to keep running HS for some platform things I can't upgrade and continue to use.

I have a newer MBPro (2019) running Big Sur

I have an older iMac (2014? I think) running Catalina. I haven't upgraded it to Big Sur, but don't think it'll be a problem. At the time it was the most beefed up iMac I could possibly buy with i7 max cpu & 32gb ram. It's still a great workhorse for us.

I would like to be able to use a single 8TB External Drive as the 1st level Backup for all 3 machines but currently they're all running 3 different OSX's - is that a problem? Can I still do the same thing using a single drive I already have?

I see 2 ways you could do this with Time Machine.

1. Partition the drive into 3 partitions. Connect to each Mac in turn and configure TM to backup to one of the partitions. Not ideal as you will need to be forever connecting the drive to the Macs.

2. Connect the drive permanently to the iMac and keep it running all (or most of) the time. Partition in two. Use one for the iMac backup. Set up file sharing (including options for TM) for the other partition and configure the two MBP to backup over the home network to that iMac. This would be my preferred choice, but may need some fiddling to get the network backups working reliably.

Definitely not a moronic question. The complications for you are likely to arise because of different versions of macOS and TM.