Time Machine on zvol tutorial needs updating for Big Sur

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Time Machine on zvol tutorial needs updating for Big Sur

Postby tangent » Sun Aug 08, 2021 8:45 am

I tried to follow the zvol option in this wiki guide, but I kept running into a problem at step 4 where the Time Machine settings panel complained "Zero KB available" and thus refused to start the backup.

I discovered several things that needed changing to make it work:

  1. Time Machine now prefers APFS
  2. It won't work with a zvol that you format as APFS Encrypted within Disk Utility. This is what gives the bogus "zero KB available" message, apparently because Disk Utility uses a different method of creating the encrypted container than the wiki's manual method.
  3. But the manual method of encrypting an existing formatted volume currently in the wiki doesn't work with APFS. You have to say "sudo diskutil apfs encryptvolume [Disk ID] -user disk" instead. It takes the passphrase interactively, not on the command line, and it does a background conversion in place, which is apparently how Time Machine likes it.

Here's a bonus tip: at the command line, say "open /System/Library/CoreServices/CoreTypes.bundle/Contents/Resources/GenericTimeMachineDiskIcon.icns", select the first icon in the resulting window, ⌘-C, then say Get Info on the disk icon and ⌘-V the copied PNG to the disk to "bless" it as a Time Machine disk. For some reason, Time Machine won't do that by itself, as it does with normal external volumes when it first starts using them for Time Machine.
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Re: Time Machine on zvol tutorial needs updating for Big Sur

Postby srirangav » Tue Aug 10, 2021 3:51 pm

Hi,

I have tried to update the wiki based on your comments (see https://openzfsonosx.org/wiki/Time_Mach ... kups#zvols). Can you see if the revised instructions for apfs work? They seem to work for me, but my setup is pretty simple and I don't regularly use Time Machine.

Thanks,

-ranga
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Re: Time Machine on zvol tutorial needs updating for Big Sur

Postby tangent » Wed Aug 25, 2021 6:57 am

It seems to be a fair merge of what I did here and then wrote about with what was already presented.

I hope we can soon get to a point where all commentary about JHFS+ just goes away. Based on download numbers for the latest 2.1.0 release, though, it looks like we have an amazing number of people on years-old releases of the OS. 10.13 seems to be unaccountably popular, for instance.
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Re: Time Machine on zvol tutorial needs updating for Big Sur

Postby nodarkthings » Thu Aug 26, 2021 1:48 am

tangent wrote:it looks like we have an amazing number of people on years-old releases of the OS.

It's not necessarily because of HFS+, as you can imagine, but because an essential app won't run on newer OSes, for example. ;)
This has led me to change my use of ZFS, unfortunately, until maybe 2.x work on 10.9... Until then I stick to 1.9.4, to be on the safe side. :)
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