New verification algorithm for NC?

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JayB
Posts: 192
Joined: Sun Jan 08, 2017 4:38 pm

New verification algorithm for NC?

Post by JayB » Wed Mar 10, 2021 10:47 am

When copying large bundles (especially apps) from a DMG to the main volume, NC (even on fast modern Macs) often takes a long time (several looong minutes) to verify if the copy process was successful. I assume that NC is using a hashing algorithm and compares source & destination file hashes.

I would strong advise switching to BLAKE3: https://github.com/BLAKE3-team/BLAKE3 … afaik this is the fastest algorithm available at the moment. It's actually insane how fast the b3sum CLI implementation already is. Moreover, to increase speed further by a couple of milliseconds per file, you can also set the length to 4 (à la CRC-32).

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mike
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Location: Exeter, UK

Re: New verification algorithm for NC?

Post by mike » Wed Mar 10, 2021 11:11 pm

This process is I/O bound, so changing a hashing algorithm is unlikely do much.
CPUs are insanely fast these days comparing to peripherals.

JayB
Posts: 192
Joined: Sun Jan 08, 2017 4:38 pm

Re: New verification algorithm for NC?

Post by JayB » Thu Mar 11, 2021 11:14 am

Would the fact that some DMGs are super-compressed play into this? E.g. an app expanded & installed would be around 800 MB, and the DMG is only 250 MB. (But once mounted, it should imho be available for read access like any other directory.)

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mike
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Re: New verification algorithm for NC?

Post by mike » Fri Mar 12, 2021 9:09 pm

I'm not sure how compression could affect the verification process...

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