timemachine backup extremely extremely slow

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Level 1

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timemachine backup extremely extremely slow

I'm migrating to an M2 Mac mini from a trusty old Late 2012 i7 Mac mini with SSD boot-drive. I figured the fastest way would be to make a time machine backup using an attached hard drive. I formatted a bare drive as HFS+ and set it up to run. 24 hours later it had backed up 90GB of a 900GB backup. I abandoned that backup as tried again using an existing Time Machine backup of the older Mac mini. I figured it would only need an incremental backup. 24 hours later I have backed up 92GB of an 800GB backup. It's tricking along at 2mb per second, on a different drive, with a different port connection and different cable. At this rate its going to take 10 days to do a TM backup of less than 1TB. Any suggestions?

Earlier Mac models

Posted on Oct 2, 2023 3:14 AM

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Answer 1

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woodmeister50

Level 7

21,527 points

Oct 2, 2023 5:16 AM in response to Ardpatrick

Have you tried using any of the free disk speed test apps like BlackMagic to see what transfer speeds are to the external drives? Also, try doing a a transfer of a very large file (1 GB or larger) to the external drives to see what sort of transfer speed you are getting.

FWIW, 900GB will take a while to transfer when copying just files but Time Machine has will take a bit longer because there is quite a bit of bookkeeping that needs to be done. Also, how long the backup takes will depends on the nature of the files being backed up, i.e. a single 1 GB file will be faster than 100,000 2KB files. With that said however, 2 MB/sec seems to be a bit slow which is why I suggested the above tests to determine if there is a Time Machine issue or if something on your system is causing a slow down.

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Answer 2

den.thed

Level 10

96,716 points

Oct 2, 2023 8:10 AM in response to Ardpatrick

I started using a Clone made with CarbonCopyCloner on a USB 3 external SSD, to migrate anything over 200GB instead of Time Machine.

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Answer 3

Ardpatrick Author

Level 1

8 points

Oct 2, 2023 3:54 AM in response to Ardpatrick

I could skip TM and set up both Mac Mini's on my home network and migrate that way. The network isn't super fast - but can certainly handle higher data rates than 2 mb per second. The question is whether the issue is to do with Time Machine itself, or whether its a transfer speed bottleneck issue. I've been using TM for over 20 years and I know its slow at times, but this is extreme.

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Answer 4

Ardpatrick Author

Level 1

8 points

Oct 2, 2023 5:49 AM in response to woodmeister50

Thanks for the suggestions. I can't test either disk right now because both volumes are listed as "ready-only". I assume this is connected to the partial TM disk images on both volumes. I might be wrong there.

But I am familiar enough with the drives to be sure that even conservatively they are well capable of 40-50 MB/Sec. Both are HDD, connected via USB 3 ports. It's hard to believe its a hardware issue.

I know small files slow down these processes, and I'm just wondering if TM is doing all the small files first, and then will speed up transferring the big files later, or something! For the moment its still dragging along at 2.5 MB/Sec. Since I first posted this morning, its backed up no more than 20 GB additionally. Very very slow.

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