Finder can't see see a USB drive connected to a Time Capsule

[I would also much appreciate answers to the following additional more-general questions:

1. Once I have the new drive in the TC, will I be able to also connect a USB drive to the TC and have Time Machine alternate backups between these two drives?

Yes, you can do that.

#2 Can I use Disk Utility to repair or partition these drives while they are connected to the TC?

No, the drive connected to TC is now a network drive. Only the TC firmware has control of the internal disk. USB disk has no control from TC or computer.. it must be unplugged and connected back onto the computer to do anything. Disk Utility is for local drives, ie plugged into the computer to SATA, USB, Thunderbolt etc.. but not ethernet or wireless which is over network.

#3 Can I also use these drives for non-time machine data?

Yes and no.. mixing TM and normal files is not great idea. The TC is not a NAS and has lots of limitations.

Apple certainly never intended it to be used this way. It was a dumb hard disk in a router for Time Machine backup of laptops over wireless. Certainly people try.. and sometimes succeed and proclaim loudly their success. Others follow and lose said files.. You should see people sweat when they realise their entire photo collection is now lost. Because using photos library live on the TC corrupted it. As a place to park files.. sure .. never use it for active files.. and especially anything stored in library.

In the end if you want a NAS buy a NAS. Expensive but can back itself up. TC cannot.

#4 Can these drives also be backed up to the cloud, e.g. using BackBlaze or Carbonite?

You can backup to anywhere via the computer.. but TC is dumb as board remember.. no smarts. So backup via computer over wireless is exceedingly slow.

Something like this.

Copy file to computer from TC.

Copy file from computer back to TC.

Copy file from TC to storage.

Check file from Storage to TC to Computer to TC.

Back to start for next file.

Over wireless (half-duplex) this will give you lessons in patience... deep dark lessons.

A NAS has the brains internally to backup to cloud storage or USB drive or another NAS.

Hi Tony..

Here we go.

[Mine is not bridged to any 3rd party router]

If the TC is the main router and you are plugged into a simple modem (single ethernet port) it is perhaps a sign of time and its age that the hard disk died and you are having issues.. It might be time to move to a better router.

[Model A1470. Can't recall how old, but the serial number is C86KX8W2F9H5]

Time capsule is classed as a peripheral and not easy to get info from serial number. Yours is the last one,, we call it Gen5 but it is called 802.11AC wireless version by Apple. Such a catchy name.

It must be more than 3 years with a dead hard disk.. and could be up to 6 years. Normal lifespan is 3-5 years with the Time Capsule to the shorter end of that being a more complicated unit than the Extreme.

Right up front my advice would be time to buy a new router. Apple is out of the business so you need to buy another brand sometime soon anyway. I like the Asus high end models as well as the Synology RT2600AC.

Either of those support time machine to a USB drive which is USB3 and just as fast as the TC internal drive. The wireless performance particularly Asus is much better than Apple routers.

For backups you can also consider adding a NAS. Synology is again the one we have tried and recommend around here. Not cheap but it will give you better performance and a lot more functionality.

Setup how.. you gave me the info I require. It is setup as main router and you only use wireless.

[Please clarify which Name you recommend changing.]

All of them.. but in particular the name of the TC. Due to changes in network protocol Apple started way back but is now beginning to bite since High Sierra the TC is much less reliable as a network target for Time Machine.

Apple is now using SMB protocol (yes that one from MS). Naming is a lot tighter.

[Would it work if I used Carbon Copy Cloner instead of Finder to do the copy?]

No .. it is irrelevant what application you use.. You cannot prepare the disk for insertion into the Time Capsule using disk utility in the Mac. It used to be possible and I have instructions on how to do it.

https://discussions.apple.com/thread/4278497

That was 2012 and I have tried all sorts of things since but nothing worked even from command line. You must put the disk into a Time Capsule.. any model will do. When you erase a drive it creates 3 partitions APconfig, APswap, Data. It then formats correctly. If you partition and format on the computer it will create hidden EFI partition and cause issues.. if you delete the EFI with command line it still throws up errors.. so no go. Once a hard disk has been erased in the TC you can pull it out again and copy files.. but even then it is not easy to get files into the share correctly. Overall I recommend copy files in situ.

[I have already done that since Gigabit Ethernet is faster than Wi-Fi, but it still took almost a day to do the first backup from the 15" MacBookPro, which has a very full 1TB SSD.

Time Machine backup to a USB drive plugged into the TC is slow.. much slower than the TC internal disk. On a good day (with a tail wind and crescent moon in the east..) you can get about 60GB/hr to the internal disk of a TC. Lucky to get 30GB/hr to the USB drive. So as you can quickly figure out a 1TB disk is going to take a while no matter where you backup to or how.

Neither Carbon Copy Cloner nor BackBlaze will copy this Backups.backupdb folder because of proprietary Apple mechanisms in it, but are apparently OK with sparsebundles. So I will do any future backups to NAS only.]

That is our general experience. Copying a backup is bad idea. Errors in the backup just end up copied to the new target anyway. You are much better using CCC to do a clean backup to a new target. CCC is hugely superior reliability wise cf Time Machine. I have already moved to CCC as my reliable backup.. I still use Time Machine to 3 or 4 different targets to keep track of errors and help people in the forum here.. but it regularly throws up the

"I just shat in my own nest. All previous backups are now useless and I am going to start over until I do it again in a week, month, year's time"

Q1: Any idea how to fix that problem?

It is not uncommon for the Mac to have issues especially if the TC is bridged to a third party router.

You need to give a bit more details..

What model TC? How old?

Setup how?

Can the 15" MBP which cannot mount the TC disk in Finder also have issues with Airport Utility?

Let me suggest a name change.. Short no spaces and pure alphanumerics. <8 characters. Password same rules but 8-20 characters.

Regardless of the above..

In Finder use top menu, Go, Connect to Server. Type in AFP://10.0.1.1 (or whatever is the actual IP address of the TC).

Make sure you save the password into the keychain.

Q2: Before I bury the new 4TB NAS drive in the Time Capsule, should I copy the sparse bundles from the 2TB USB drive to it, connected through a SATA to USB adaptor?

NO.. don't do copy before the install. The partitioning is special. After you install the disk in the TC you need to do a quick erase. This will partition and format the disk for TC use. Otherwise you have disk errors forevermore.

If you copy before this you will end up wiping everything you copy. You can pull the disk after the install and copy the sparsebundles to correct Data partition. Although I am guessing your use of the term bury rather than install suggest you have a Gen5 TC and installing the disk is rather a pain. And it is.. painful. I would almost say get an earlier model TC second hand.. you can pickup a Gen3 or Gen4 really cheap.. and they are much easier to work with.

I would buy a thunderbolt to ethernet dongle so you can copy files directly from the USB disk plugged directly to the computer over to the installed hard disk in the TC.. this is not as fast as direct copy but better than using wireless by miles.

Installing a replacement drive in the AC tower model TC is messy. Instructions on ifixit are available.

https://www.ifixit.com/Guide/Airport+Time+Capsule+A1470+Hard+Drive+Replacement/61924

Be very careful not to tear the ribbon cable.. and be prepared to remount the disk with your own foam rubber inserts because the old ones will not fit. Getting all the connector off and on without tearing off the socket is also not easy. These things are poorly designed internally. The older model was far superior.

Also just note that WD red is excellent drive but you don't need a NAS drive.. any 3.5" drive will work and a cheaper desktop one is usually fine.. low power slower type being good for the situation. Apple just uses desktop drive.

What model of Asus router were you referring to?

I run RT-AC88U which is big and ugly. Very industrial. I love it.

Stuck in the workshop so a no go zone for unqualified personal. (No oversight by SWMBO.. she who must be obeyed!!)

I recommend anything later or above that model. AC86U is much later domestic style with red racing stripes (Ugly x 3 cf the older one IMHO) New AX88U is worth a look.. but AX wireless standard is not 100% yet. Asus produces new firmware regularly so bugs will be fixed.. but you are buying bleeding edge.. expect to bleed a bit.

If i connect a USB3 drive to it's USB port, will it become a NAS drive?

NO.. a NAS is dedicated box. It will be faster and more robust with lots of functionality in the firmware you won't get in a router. In fact the better end NAS will run a Celeron 4 core processor or even higher. It will run loads of apps that would have required a dedicated server in the past. e.g. Survelliance software. A router will run a 1.8ghz dual core arm processor say. It will only have enough RAM and ROM to do the job of a router.. plugging in a hard disk is a convenience. For many people sharing files and backing up is perfectly fine using a USB hard disk on a router. NAS is a much bigger outlay but you get what you pay for!!

Can I use a powered USB3 hub to add a second NAS drive?

Yes, although it can be tricky. Remember there are disk size limits, Speed and latency of USB will never match NAS with SATA connected drives.

The Synology Router is a step above most though since its firmware is derived from NAS and is built with far more ROM than any other standard router I know of. 2GB. Most NAS will start with 4GB now.

Is there a way to set it up so that the two drives operate as RAID1? Disk utility can do that for local drives, but probably not NAS drives.

Correct. For Raid setups you need a NAS.