ddrescue: Unaligned read error. Is sector size correct?

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AW_shmbhami
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ddrescue: Unaligned read error. Is sector size correct?

Post by AW_shmbhami »

I have an iMac 2017 with a FusionDrive consisting of 1 HDD 1TB plus a SSD 28GB. I want to clone the FusionDrive as one entity to an image-file on an external USB drive with DDRescue-GUI running on independently booted Mojave. The desination volume is case-sensitive APFS device block size 4096 Bytes and allocation block size 4096 Bytes.

It is possible to clone physicals drives HDD and SSD without any problem and error.

When cloning the synthesized FusionDrive /dev/disk2 with DDRescue-GUI process starts and runs for some minutes. Suddenly process stops and throws error message: "ddrescue: Unaligned read error. Is sector size correct?" DDRescue-GUI aborts with status 1 and asks also if destination is full, but there is plenty of space.

Device block size for HDD is 512 Bytes. For SSD device block size is 4096 Bytes. SSD size is 54687504 512-Byte-units.

I think DDRescue starts with SSD 4096 Bytes and then should switch to HDD 512 Bytes, but can't.

How can I clone the FusionDrive? Should I try to clone to disk instead of image file? Does not using "direct disk access" handle this?

Rgds
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hamishmb
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Re: ddrescue: Unaligned read error. Is sector size correct?

Post by hamishmb »

Hi there,

Interesting question, but unfortunately I have never had a fusion drive so can't test my hypothesis, but I suspect you may need to run macOS-specific tools to do this.

Hamish
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