Time Machine - Create Duplicate Backup to Start Dual Backups

[Le Big Mac]

I have a time machine backup going (network). I'd like to get a second drive to have a second backup, and then alternate which drive Time Machine backs up to every so often, preserving the other offsite.

That first backup takes forever, especially over a network. Is there a way to copy/clone the current backup to a new drive, and then work it into the A/B backup system? Ideally, I could just copy the contents of the existing drive to the new one and then go from there. But I suspect that will create some sort of problem.

 

[Bigwaff]

I have a time machine backup going (network). I'd like to get a second drive to have a second backup, and then alternate which drive Time Machine backs up to every so often, preserving the other offsite.

That first backup takes forever, especially over a network. Is there a way to copy/clone the current backup to a new drive, and then work it into the A/B backup system? Ideally, I could just copy the contents of the existing drive to the new one and then go from there. But I suspect that will create some sort of problem.

No. Each TM backup destination will require a first back up. If your second is an external drive (i.e. USB), the first back up should be pretty quick. I implement this pattern as well, except I have three TM destinations - a NAS for daily back ups, an external SSD for weekly back ups, and an external HDD for monthly back ups, which I then store offsite.

 

[HobeSoundDarryl]

My opinion is just let Drive #2 take the abundant time to create its own TM backup (too). In other words, let one "take forever" and when it is done, let the other "take forever" again. After those lengthy backups, subsequent TM backups will be very fast. Suggestion: get each going at night and go to bed, letting it take those "forevers" while you sleep. Both forevers will pass much more quickly if you sleep through them.

And good job on adopting an onsite-offsite arrangement with regular rotation. Keep that offsite one reasonably fresh and you can sleep well. Even in the worst scenarios like fire-flood-theft, that one fresh backup offsite can almost entirely save the day-ta.

 

[Le Big Mac]

Frustrating but not surprising!

To be clear, I already have a full backup/TM history on Drive A, so I just need to start a new backup on Drive B . . .

(While I'd like the older history on both, that's less important. I don't tend to delete things I need to get back.)

 

[HobeSoundDarryl]

Yes. Pretend like you don't have A, plug in B and let it create a full TM backup (too). You can let it back up while you sleep so that it doesn't seem to take so long.

Go ahead and take A to the safe offsite location.

At whatever pace of drive rotation you desire (my choice is about every 30 days, or just before I do any extended travel), swap the offsite for the onsite drive and then let what was the offsite take over as the TM backup drive for the next period. Then, repeat this switch when it is time to swap again.

KEY: be diligent about those rotations. You don't want to tire of offsite-onsite swaps such that the offsite one is 6-12 or more months old and thus all new files you've created or added since it was last used are in full danger of being lost in a fire-flood-theft or similar scenario. Those scenarios are very likely to take out BOTH the master files on the Mac and the current TM drive sitting near it. The offsite TM backup drive must be fairly fresh to really make this work well.

Also, there's no loss if you are doing these new backups one after the other. They will basically be identical backups unless you are creating or adding new files to the Mac between backups. I'll presume by "older history" you probably mean you've been backing up to A for some period of time, so a new backup to B will have less "back in time" history. However, that will eventually take care of itself because when A is in use it will eventually start deleting oldest versions to make room for new version backups while B will continue filling until it too must start doing that. Once both are doing that, they are likely to be VERY SIMILAR in terms of what they hold (assuming they are both the same size storage). More simply, they will likely have just about identical "back in time" histories available to you.

 

[Le Big Mac]

Follow-up question - I have this going, so I now have two backup disks, call them A and B.

Currently B is connected and A is offsite. Time Machine still wants to backup to A, at least every other time, so I get an error. I can then backup to B.

Any way to make this smoother?

 

[ThrowerGB]

Try going into TM Settings. From there, remove one of the two disks, say TM B. Then next time, add TM B and remove TM A. This way takes about a minute or so and shouldn't give any errors.

 

[HobeSoundDarryl]

That's exactly how to do it. Since B is your current TM drive, you can go into TM settings, choose the A disc, hit the minus sign to tell TM to stop trying to use A. Then get A offsite for the time period until you want to rotate the drives.

When the time comes, bring A back, do the same removal of B, add A as TM disc and get B to the offsite location. Then A will be in charge of backups until you want to rotate them again.

What will happen when you switch is the first new backup to the offsite one will take a little longer than "normal" because there will be more to backup to "catch up" the replacement drive. But it won't be nearly as long as the first-time backup. It's not starting over each time, just "adding to" since the last time it was connected. If that's a week, it will need enough time for a week's changes. If that's a month, it will take a bit more time to "catch up" for a months changes.

Incidentally, if you ever add a THIRD drive to the mix such as a Synology NAS or even just one more drive, you can have the 2 selected that are at home and TM will automatically switch between the two every hour. If we invent "C" for this example, B & C would be getting new TM backups every other hour respectively... until you rotate A for B and then A & C would be getting new TM backups every other hour respectively.

 

[Le Big Mac]

Thank you both - I’ve seen the behavior with two on-site drives. I’ll delete the A drive for now - I was worried doing so would create a mess when I rotate A back in, but appreciate it won’t. (Yes, understand why it will take longer.)

Only issue for me is this is a network backup with spouses laptop using it too … so I’ll have to get onto her laptop to switch as well each rotation.

 

[HobeSoundDarryl]

Yes, you'll need to do it on both Macs. It's quick & easy.

However, with that bit of information, I encourage you to start saving up for a NAS like Synology. That would give you network storage you can share between both Macs all the time and never need to "eject" it. And Synology in particular has very nice support for TM.

Your post reads like you probably are connecting a single drive to- I presume- a router. But you might want to eventually mix in a NAS like that and let it be your network TM backup. It's "for dummies" easy to let it be your long-term, multi-Mac backup. It is your always "at home" TM backup and either or both drives can then be your offsite backup drives, perhaps even just using one of them for each of your Macs: A for yours and B for the wife's. Bring both home, hook them up, do a manual backup, get them back offsite ASAP.

Or perhaps back up to A on your Mac when ready to swap, then hers, go swap it and then keep B around until time to swap again and backup your computer to B, then hers then go swap again.

This is not an urgent need since you are already doing a smart thing of having a fresh backup working at home and a pretty fresh backup stored offsite. But when you can, this is a very easy TM option that can just always be available for backups of multiple computers and "just works."

 

[BigBlur]

I agree that a NAS would be the most ideal solution. You can back up multiple computers to the NAS without having to physically connect anything.

Then for the secondary backup, you have a few options:

• Backup the NAS to an external disk. My Synology NAS has a feature where you just plug in a disk and then push a button on the NAS itself to start the backup.
• Get a second NAS to put somewhere else, like at a family/friend's house or business if you have one, and sync/backup to the second NAS over the internet.
• Backup the NAS to some cloud storage provider, like Backblaze.

 

[Le Big Mac]

My setup is external HDDs connected to a Time Capsule, with TM over our network. IE more or less NAS.

 

[HobeSoundDarryl]

OK, so both you and your wife's Macs can dynamically back up to that Time Capsule (TC) NAS drive. I'd just leave that connected at all times and not really think of it is as one to swap to offsite. That will be easy, always available for backups, always available for "back in time" restorations, etc.

Then, I'd allocate at least 1 more DAS (standalone) drive and dynamically connect it to each Mac regularly (maybe weekly?) and manually TM backup each Mac to it. After both backup, get it to a secure offsite position. When it's time to freshen up the offsite, fetch it, do manual backups to it again, then right back to the offsite location again.

If I could swing TWO such drives, I'd allocate one (drive) to your Mac and one to your wife's and then do it the same way. TWO drives would be going back & forth to the offsite location.

OR, I could do the manual backups of both Macs to Drive B, take it with me when I go to where A is stored, leave B and bring A back with me. Then, when it's time to swap them again, TM backup both Macs to A, take it with me to where B is stored, switch A for B there, bring B back with me and thus be ready again.

Between the 2, I'd probably just allocate an individual drive to each Mac and run both to the offsite storage after freshening up the backups. Why favor this option? See below...

NOW, if I really want this to be flawless, I'd do something a little different than just described:

I'd split the disc attached to TC, basically allocating dedicated space to your Mac and your wife's Mac. This might be "partition" or "volume" but the idea is to take total space and actually split it into dedicated space for each Mac.

WHY? Because two Macs sharing the same space will eventually have one of the Macs hog up most of the space. One Mac will end up with lots of "back in time" capability while the other will hardly have any "back in time capability." Splitting the space into 2 separate TM storage spaces allocates a fixed amount of space to each Mac so there is no "competition" for that shared space.

For example, if the TC NAS drive is- say- 16TB and both Macs should have the SAME amount of space, I partition or otherwise split 16TB into two 8TB halves. Then each Mac gets 8TB worth of space for TM on that drive. If your Mac has huge data and your wife's has only a little data, your 8TB portion will soon be near full, while hers would be barely used at all at that point in time.

And for my DAS drives, that's why I probably favor allocating each drive to each Mac vs. also sharing space on them. If I want to share space on them for both Macs, I do the same thing: split the total space into 2 halves so that each Mac has it's own dedicated space for what will be it's offsite backup. For example, drive A might be thought of as A (part) 1 and A 2... or A 0-50% and A 51-100%.

The main idea here is that purely sharing space on NAS or DAS will eventually have one Mac backup dominating the other. One will consume almost all of the space and the other will have hardly any space... thus one will have much more "back in time" capability than the other.

 

[Le Big Mac]

OK, so both you and your wife's Macs can dynamically back up to that Time Capsule (TC) NAS drive. I'd just leave that connected at all times and not really think of it is as one to swap to offsite. That will be easy, always available for backups, always available for "back in time" restorations, etc.

...

The main idea here is that purely sharing space on NAS or DAS will eventually have one Mac backup dominating the other. One will consume almost all of the space and the other will have hardly any space... thus one will have much more "back in time" capability than the other.

1) Okay, so you're suggesting a different model. A "live" backup that's always running, plus a periodic offsite backup that I bring home every so often to perform a backup. Right?

2) I've already partitioned both drives. That said, it appears in Sequoia you can achieve the same by setting a size limit on the backup. I haven't tried that, because old habits die hard, but wouldn't that work for those who actually update their ways?

 

[HobeSoundDarryl]

1. Yes, I didn't understand your full situation in prior posts. I do think that "live" backup that's always running on that Time Capsule is fine to just leave there at all times. And then, yes, a periodic backup (or two if you like) to be stored OFFSITE. Fetch, update, return to safe offsite location.

2. And yes, my apologies, I forgot that TM can set the size limit. Mine has been set up for a good while. That size limit can cover that base of not letting one Mac backup dominate the other over time. So yes, use the size limit vs. jumping through the new hoops I offered in the prior post (they would work too but time limit is just as good). The key concept is simply making sure that both of your Macs have a reasonably good amount of "back in time" capability too. That should work fine.

Again, my apologies- I had forgotten about that option. Good catch on your part.

 

[Le Big Mac]

Then, I'd allocate at least 1 more DAS (standalone) drive and dynamically connect it to each Mac regularly (maybe weekly?) and manually TM backup each Mac to it. After both backup, get it to a secure offsite position. When it's time to freshen up the offsite, fetch it, do manual backups to it again, then right back to the offsite location again.

Back with a follow-up, as I'm seeing your point here.

I now have two full backups, one slightly more updated than the other (currently attached). Both are network backups.

Can I connect the "B" drive (let's say the one I'll keep offsite and periodically backup onsite) via USB even though it's a sparsbundle? Or will that make a mess of the backups I already have? Of course, I could start all over again . . .

 

[HobeSoundDarryl]

Yes, no problem. Attach it, add it as a TM backup just like you are doing it for the first time. Mac will assess it and then add to the existing sparse bundle.

Then when it is time to swap them, you disconnect it as a TM drive and put the other one back in charge. My own approach to DAS HDDs is to backup to an "A", disconnect it as a TM backup drive and take it with me to the offsite location (bank safe deposit box), swap it with "B", bring "B" back with me and re-add it to TM. Now "B" basically "rules" as the DAS TM backup until it's time to repeat this process.

Or if the question is can BOTH be attached at the same time, yes! Instead of backing up to one every hour, Mac will automatically alternate to each… such as A on the even hours and B on the odd hours. The negative here is that during this time you have NO backups offsite, so the odd risk of a fire/flood or similar could take out all backups. So if you are thinking this, I'd encourage you to NOT do this but instead do as described in the prior paragraph. During the swap time, you'll have two OFFSITE instead of two onsite, so you'll technically be a bit MORE secure against data loss during that swap time.

Don’t imagine sparse bundle issues. Mac is smart enough to recognize an old sparse bundle and then update it when reconnected as if it was never disconnected… EXCEPT that it wouldn’t be exactly the same as if you left it connected all of the time because there won’t be multiple versions of select files as there would be if you have updated some files many times since it was last connected.

For example, let's say you are writing a paper in Pages and working on it over many days. The local DAS is capturing file updates every hour. Obviously, the offsite is not. Let's imagine there has been 20 file updates during this time. You swap your TM drives and now the one that was offsite takes over as onsite. It can't magically add 19 versions of the file now- only #20 (latest) version. Let's imagine you have 20 more version updates before next TM swap day. This local drive may then hold #20-#40. When you bring the offsite back to take over again, it can't match that (#20-#40) so it will update starting with #40 when it takes over again. Conceptually, it will still have #1-#20 and now #40 in its TM archive. The offsite one now has #20-#40. No issue with this. This is just how TM works in this scenario.

Ask more questions if these don’t quite cover it.

 

[Le Big Mac]

Basic question, which I think you said yes to, is if Mac will back up over direct USB connection to a sparsebundle originally created over network.

 

[HobeSoundDarryl]

I haven't done THAT in a long time but last time I did, it did. In fact, I often did it mostly the OTHER way: create the initial big backup locally (direct connect to USB, for the added speed of creation) and then moved that to a network connection, making it a NAS. No problem with that. I don't think the connection type matters as much as the sparse bundle itself. When you add a new drive local or network, Mac will assess the existing sparse bundle, recognize it and start using it for future TM backups.

Update: with a bit more thinking, I now THINK I recall that I might have had to create the TM backup on the drive attached as a NAS to get basic setup in place. Then stop the TM Backup and bring it to the Mac for a DAS connection (faster initial TM backup). Let it do the full backup and then back to the NAS again where it remained for the rest of the time I used it for backup. But again, it's been a LONG time since I've done this, so I may not be perfectly recalling this.

Ultimately, you can just try and see what happens. If it can't do it, you can have it make a brand new "first" backup while you sleep and then use it as a DAS. If you are worried about preserving some files on it, perhaps switch to a new drive for a DAS backup, use it for a few weeks to build up some history and THEN see if your NAS drive will continue backing up when switched to a DAS. If it says it can't and offers to create a new backup, you could reject that option to preserve the NAS backup for longer if you need to preserve the files. But if it "just works", you can put away the temp DAS you were using for those few weeks as an additional, recent, complete backup.

 

[ignatius345]

I have a time machine backup going (network). I'd like to get a second drive to have a second backup, and then alternate which drive Time Machine backs up to every so often, preserving the other offsite.

I do exactly this, but I have the drives connected directly via USB. The swap takes all of 2 minutes.

IMO doing Time Machine backups over a network adds a ton of fragility and slowness to the process and doesn't really get you anything except, I guess, the ability to back multiple Macs up to one destination. I don't need that, myself, and the wired connection is massively faster.

 

[ignatius345]

KEY: be diligent about those rotations. You don't want to tire of offsite-onsite swaps such that the offsite one is 6-12 or more months old and thus all new files you've created or added since it was last used are in full danger of being lost in a fire-flood-theft or similar scenario.

I rotate mine every 30 days to my desk at work. I have a location-based reminder that triggers every 30 days when I get to work and that seems to work quite well for me. All my most important stuff is also synced via iCloud Drive. I know that's not a backup service, in a full on home disaster scenario (which I had once, ages ago, when my Mac and backup drive were stolen in the same burglary) those synced files would plug the gaps quite well in what's on my offsite backup.

 

[HobeSoundDarryl]

You’re the perfect case story for onsite-offsite. Fire-flood-theft happens. Sorry for that loss but glad you covered yourself in this way. Hopefully, all the people that read this thread over time will see the post, think about that real example and get their own onsite-offsite backup system in place BEFORE they actually need data recovery in any such scenario.