Recommendation on disk storage device sought

plug into the back of the existing Time Capsule *or* the USB port of another router (so that when the Time Capsule dies I can plug it into my cable company's router).

The Time Capsule can break.. when it does you can remove the hard disk (assuming that wasn't the broken bit).. plug it into a USB enclosure or adapter of some sort.. very cheap ones are plentiful. Then plug it into your computer.. You can then access the TM Backup or whatever files you like.

You can backup the TC by archiving it to a USB drive.. so plug a Mac formatted (HFS+) into the TC.. and in airport utility go to the disk tab and select archive.

NOTE.. you cannot plug the USB drive into your cable company router. It will not be able to read HFS+ OR Time Machine will not work.

However you can plug it straight into the computer. Time Machine can then read the backup.

I'm looking to purchase an external drive to use as a backup to my backup

Let me suggest backup your backup.. is not a great plan. It's like photocopy of the photocopy.. it keeps getting worse on each generation. Errors simply get copied.

It is much better to plug the USB drive into your computer and use a better backup software.

I recommend Carbon Copy Cloner as best balance between cost, features and performance. SuperDuper is also popular but not as comprehensive.. Chronosync is more complicated and expensive. (I get no kickback.. and buy a license like anyone else). It is free to use for a month.. and you can make a bootable clone of your computer. This is far far superior to making another Time Machine backup. You can simply boot the computer from the clone immediately after it is created before you load Mojave.

As far as I can tell, Time Machine only allows one backup device. I don't see any way to have a second backup device.

This is not visible in the interface.. but is easy peasy.

Click on Add or Remove Backup Disk.

A list of available disks will pop up.

Select the one you wish to use.

Click use disk.. you will get asked for password for network drive and it will be added to the list.

That would give me a total of three disks.. so I simply remove what I just did.

You also should get a warning about continuing to use the old disk or deleting it.

Any suggestions?

For long term.. a Synology NAS is a great solution for network backup. I also use one like Tesserax and recommend them.

It is expensive and a router with USB drive is also possible.. the best is Synology again.. RT2600AC. But there are other brands that do support Time Machine.. with varying reliability. Most testing does not go long enough. I found many router were not reliable past a few months. So be a bit watchful of any claims made without long term testing in real world conditions.

What I want to have happen is that after Time Machine writes a backup to the Time Capsule that it writes a SECOND backup on the second drive with the SAME (or essentially the same) information.

Just to clarify here, you can have Time Machine back up to as many different drives as you want. For example, if you already have the Mac set up to back to the Time Capsule, simply add another drive to the network (assuming that your router supports Time Machine backups at the USB port on the device)......or......preferably directly to the Mac. Then click the Add button in Time Machine Preferences to have the Mac back up to that new drive as well.

Backups to a drive connected directly to a Mac will go faster and be more reliably, so is the recommended method for backups. Depending on the drive that you choose, you may need to add an Apple adapter to mate with the available ports on the Mac.

The first backup to the new drive will copy everything on your Mac over to the backup drive.

Once that is completed, Time Machine will automatically alternate backups to each drive. So, rather than having Time Machine back up once an hour to the Time Capsule,, Time Machine will back up to the Time Capsule one hour and then backup to the other drive the next hour and so forth.

If you had 3 backup drives set up, Time Machine would go in a 1, 2, 3 sequence automatically then start over again with #1 etc.

I would suggest that you consider getting a dedicated NAS device that supports Time Machine. I have been using NAS's, provided by Synology, for this purpose. It does not connect by USB, but by Ethernet which both the current Time Capsule and just about every other make of routers out there ... so getting it connected to your network will not be an issue.

The Synology NAS is basically a mini computer with drive bays. Depending on the model, it can have as few as two drives to four, and more, if you get the extended drive bay option.

FWIW, I use mine for a number of purposes, including Time Machine for my Macs, an equivalent backup app for my Windows PC, a media server, a file server, and to perform as a VPN server.

I have a Macbook Pro and, as you know, Apple has decided to remove traditional USB ports from the Mac, as well as ethernet ports. Unless the device I buy comes with the correct USB cable type connection, I cannot connect it to my Mac.

You did not indicate the MBP was post 2015 model.

Tesserax has indicated you can in fact buy USB-C hard disks although they are more expensive than standard USB3 this is now much more common than Thunderbolt1 or 2 and prices will come down.

For now it would be better value IMHO to buy a thunderbolt3 dock like OWC models with lots of useful ports and include charging on them.

https://eshop.macsales.com/shop/docks/owc-thunderbolt-3-dock

At the moment you are stuck in a hard place. Apple has dropped the Time Capsule from their lineup but have not so far introduced a cloud based alternative. Since their plan is to change to cloud computing at some point they will fix this hole. For now you can use cloud storage for all your user files. It does not cancel out the need for whole backup which is much less useful if your internet speed is slow. Some backup software is offered which will do a full Mac OS backup to cloud. Cost wise it will hit you in monthly fees though.

With your budget the best I can suggest is to buy a USB portable drive.

When they advertise the drive as Time Machine compatible that simply means it is Mac formatted.. and that applies to any hard disk.. it can be Mac formatted. Since you don't want to buy anything else just make sure it is Mac formatted before you buy.

You can plug it into the Time Capsule and setup Time Machine to use the USB drive as a separate backup as I posted in the previous reply. No issues doing that. As Bob remarked it will simply backup in sequence.. each hour it will backup to one and then next backup to the other. If the TC breaks down.. hopefully not for the next couple of years.. getting your files back will require purchase of an adapter if not a full dock.

From a reliability stand point.. I would not buy portable disk greater than 2TB. There are plenty to choose from.. WD, Seagate, Toshiba, LaCie etc. The LaCie can be a good choice if they are not too much more expensive.

I do not think it be without issues. You may need to unplug the USB drive fairly often to get it recognised by the system. There is no fix because Apple have given no access to controls in the Time Capsule.

The rest of your points have been covered.

My favourite external drive is Toshiba or HGST Touro.

Experience says they are very reliable but NOT to plug into a Time Capsule. I tried and was very disappointed.

The issue was not the Touro Deskpro which plugged directly to the computer works superbly well, but rather Apple's extremely limited USB driver set in their routers.. particularly the latest models.

I even tested with a USB hub but the issues of losing connection persisted.

Go with the LaCie USB-C which should also fit USB-A and plug straight into the TC. There is a luck of the draw in these things though because the USB chipset is often changed without any notice to end users.

Self-powered drives do have limitations and the AC model TC (last one made) still uses USB2 with limited power output. So as with everything your YMMV.

It is impossible to get 5Gbit/s out of a mechanical hard disk.. unfortunately what is written on the drive case is rubbish. It has nothing to do with the size of the disk.. the speed is the Max speed of the interface.. a mechanical disk with slow RPM like that used is most external drives should be capable of close to 100MB/s (ie 800Mbits/s) but the write speed can easily be just half that.

Be careful not to confuse bits and Bytes. We try to be consist and use b for bits and B for Bytes. Bus speeds and network speeds are given in bits/s and file transfers are measured in Bytes/s just to make life confusing.

USB3 is capable of 5Gbit/s but it is seldom possible.. and never with mechanical disks.. that is shear fantasy and no company should advertise what are effectively false numbers.

You can create a large file to test with in Disk Utility.

https://support.apple.com/en-au/guide/disk-utility/dskutl11888/mac

I still need to get an external drive to supplement the Time Capsule drive. Now I'm back to square one and I'm leery about LaCie.

Do the speed test before you send it back..

NOTE you can have activity monitor open while you do the transfer and check the speed after it is completed.. or just use a stop watch in your phone.

Here is the whole test procedure I have just run.

Create a large disk image using Disk Utility.

I made it 3GB

It saves as test.dmg on your local hard disk.

With activity monitor open copy it to the USB disk.

You can then copy it back again to the computer replacing the existing one.. the DMG is empty but it still takes the same time to be written.

Then you can see the speed in the activity monitor. The file is first written to the USB.. then gap then written back to the computer. You can see the write speed in the second test is slightly faster.. due to read speed being better than write on the mechanical external drive.. but this is limited by using USB2. Still I can get 40MB write and about 43 read.

Create a new user. Give full admin rights.

Then log out of your current user and login again with this new user. That often gets around setup issues.

Otherwise what you really need is a clean install of the OS. Which I know is where you started this whole discussion.

I suggest you download Carbon Copy Cloner. It is free to use for a month. Based on rsync it is a hugely better app. Create a bootable image of your drive to the USB. And test it.. simply hold down option key at the chime and select the USB as boot.

You can then make sure you have all your files, emails, passwords etc.. everything should be intact.

Then I recommend you download mojave and make a bootable installer on USB stick. Do not upgrade install.

https://support.apple.com/en-us/HT201372

Format your main drive in the Mac and clean install mojave.

You can then use migration assistant to recover your files and settings from the CCC clone.

Is this a desktop LaCie with external power supply? Or portable using USB power.. in which case it is using SMR disk.. and I indicated above not to buy disks >2TB in 2.5" format.

Time Machine estimated time can be wildly wrong at the start of a backup.

You should just run the backup.. Time estimates like 13min are based on average speed of a single large files.. but file transfer speeds for lots of tiny files will exceed that 10x due to the time spent filling indexes. And Time Machine is very slow.. first backup usually runs around 50GB/hr.. so I would expect your 480GB of data to run at around 10hours. Much more than copying takes place.. it verifies files and does spotlight index.. all of which take time. Incremental backups once you complete the full backup will only take a minute or two unless you have monster files like bootcamp or parallels virtual disks.

Do a speed check.. This is completely apart from Time Machine.

I have 5x video files of 1GB each. I copy these to do real world speed measurements. So in Finder create a new folder.. e.g. test.. copy a file of 1GB min to the disk and back from the disk. You can rename it so then you have two files and so on or replacing the originals. You should easily get speeds of >100MByte/s. You can open activity monitor to the disk tab to check speed.

You can also download a speed test software like Black Magic. I prefer copying real files as it gives me a better idea.

If the speed is very slow.. <50MByte/s write you do have a problem..

Check with LaCie or return the disk to the store. Make sure it is formatted correctly.. Mac OS Extended Journaled. And the disk is GUID partitioned. Disk Utility first aid will be able to check it.

Return via Amazon is easy peasy. Just make a return request if you are not happy.

You cannot use any tools while the backup is going on.. so cancel the backup.. 10GB/hr is too slow.

Do the tests I listed.

Make sure you can mount the drive in finder. You cannot use black magic unless the drive is mounted.

Sorry you have not had much luck with this.

It uses an SMR disk (a much more compact data format which is SLOW) which is why I said DO NOT ORDER portable disk over 2TB.

I can copy files to it manually.

What speed do you get? Move one or two very large files and give me the speed or the graphs as screenshot from activity monitor.

Black Magic refuses to do a test to the device saying the device is "read only".

That is really odd. Format the drive using disk utility.

Create a folder in Finder.. Make sure your login user has full admin rights.

Test again. If it still has read only something is wrong .. and to test you really need to give it a try on another computer.