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Time machine problem

Avatar Michael Corgan
A new SSD designated as my Time Machine Disk is not accepting back-up attempts. I have so far connected it a) direct to the iMac, and b) via the Apple keyboard, to no avail. I have tried repairing the drive using Disk Utility but that failed. I have followed Apple's instructions to verify backups, but the option to do this is greyed out. Incidentally, the new SSD was bought because a previous SSD went the same way, though that one functions perfectly as a storage drive.Has anyone a suggestion to overcome this problem.

Re: Time machine problem

Avatar Trevor Hewson
What format is your SSD? I believe Time Machine prefers APFS.

Re: Time machine problem

Avatar Michael Corgan
It, and its predecessor, are both formatted as APFS drives Trevor.

Re: Time machine problem

Avatar Mick Burrell
What was the message you got when formatting failed?

What form is the SSD? (Is it one you've put in an enclosure or one that has its own enclosure? How is it powered?)

I think that TM will format the disc if it's not the correct format when you "choose" that disc.

Re: Time machine problem

Avatar Michael Corgan
The message is "Time Machine couldn't back up to Time Machine Disk". The SSD has is own enclosure. The puzzling thing is that Time Machine succesfully backed up to the disk 8 imes while connected via the Apple keyboard before going on strike. Nothing was changed, I tried connecting direct to the iMac - same message.Obviously some change must have taken place, but I can't think what it might be. This disk and its predecessor have gone the same way - indeed the current one was purchased specifically to replace what I thought was a faulty drive, which, however, is functioning perfectly as a normal external hard drive. Both were formatted as APFS drives.

Re: Time machine problem

Avatar John Nicholas
When I moved to a new external drive, I wanted for convenience of positioning the drive to use the USB cable I had used with my earlier powered drive, rather than the shortish one supplied with the new drive.

I got a similar message as I recall. But using the shorter cable supplied all is fine. Something to do with the new drive using the cable both for data and for power. Too long a cable means power loss.

Re: Time machine problem

Avatar Richard I
I am just working out how to use an SSD externally on my mac. I found that the following help page from Crucial covers some interesting issues arising between SSDs and Macs which may help you: https://uk.crucial.com/support/articles-faq-ssd

I also read somewhere that if TM fills up the SSD (including the last 10%), then the SSD cannot do it's housekeeping (such as levelling wear etc) and this can lead to drastic slowdowns.

Re: Time machine problem

Avatar Michael Corgan
Thanks both. I am using the cable that came with the SSD, John. As the drive functioned perfectly for the first few back-ups I have to assume reformatting it in APFS worked, and of course the drive is filled to less that 5% at the moment. So, no nearer an answer! There seems to be nothing relevant on the Crucial site. Maybe I'll try and contact them direct. Watch this spot!

Re: Time machine problem

Avatar Tony Still
What can you see if you just open the drive in Finder?
Have you tried 'Repair' in Disk Utility on the drive, lest it's had trouble dismounting or whatever (yes, I know APFS is supposed to cope with all that).

If you are on an older version of macOS, you might do better to format in HFS+ (macOS Extended Journaled).

I would always advise connecting an external drive directly to the computer: intervening devices (eg your keyboard) can bring a variety of confounding issues (ironic that you have had more success the other way about). Do you think you might have a 'bad' socket on the computer perhaps?

Re: Time machine problem

Avatar Michael Corgan
Opening the drive shows the backups made after the drive was installed. The iMac is running Big Sur. The socket on the computer to which I connected the SSD is used by the printer hub and works perfectly for that.

It seems to me that some process takes place that somehow alters the connection between these SSDs and the Mac. Running First Aid, as Repair is now called fails with a report theat the SSD could not be dismounted and the message that "the repair could not be performed because one or more volumes are mounted"

Re: Time machine problem

Avatar Michael Corgan
Forgot to say that Disk Utility shows just one volume for the Time Machine drive.

Re: Time machine problem

Avatar Euan Williams
Peripherally: If Disk Utility First Aid / Repair fails ("can't unmount") I manually use the Unmount button (further along) to unmount and then Disk Utility works properly.

Re: Time machine problem

Avatar Tony Still
One more long-shot if Euan's idea doesn't help, check the disk's permissions. In 'Get Info', my back-up disk has:
Read & Write for the users 'system' and 'wheel'
Read Only for users 'everyone'

Re: Time machine problem

Avatar Michael Corgan
That didn't work, Euan. Got the same message as the previous repair attempt. Still can't understand why the two drives functioned initially and can't think what might have changed their operation.

Re: Time machine problem

Avatar Richard I
When I recently set up a time machine drive (not SSD) I formatted it to macOS Extended Journaled - this worked fine. You could try doing that….

Re: Time machine problem

Avatar Tony Still
macOS Extended Journaled is the better choice for a rotating hard drive but APFS is the direction that Apple is going. APFS is designed for SSDs and is the better choice there unless the Mac is running an older OS (I would say High Sierra or older).

However, if you're desperate, you could still try it.

Re: Time machine problem

Avatar Michael Corgan
An update:

Having disconnected the recalcitrant SSD for nigh on a fortnight I thought I would give it another go. Plugged it into the Mac wired keyboard and it worked. I wonder how many backups it will do before going back on strike. Watch this spot for the next thrilling instalment.

Re: Time machine problem

Avatar Eric Jervis
Hmm, sounds to me as if its contracted a Variant of Concern; have you informed Savij Javid, (AKA Gollum) the Minister of Health?

Re: Time machine problem

Avatar Lionel Ogden
Could it be that there is a dodgy connector either on the SSD or your Mac which is giving you an intermittent performance.

Re: Time machine problem

Avatar Michael Corgan
This problem has occurred with 2 SSDs, Lionel, and the later one was connected via an external USB hub, the Apple keyboard and directly into the iMac, so I do wonder where a faulty connection might be. I'm peeved that I binned the first SSD! The current one is behaving itself as Time Machine at the moment, so the other one might have rejoined the ranks of the conscious had I persevered.
 
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