Local rsync disk to disk slow

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Local rsync disk to disk slow

Michael Lemke
I am copying a large directory tree from one internal disk to another USB 3 connected disk on the same computer with this rsync line:

rsync -ahPvzHA --delete /d/Images /q/

This copies files at a rate of 20MB/s. If I copy the same tree with Windows Explorer I get about 90MB/s.

Why is this? The chosen options don't seem to affect the result much.

I noticed three rsync processes one of which is CPU bound at a single core and therefore limiting the performance. This process reads the source files. The other two rsync processes don't consume a noticable amount of CPU time and one of them writes the destination files.

Are there any options to speed up the process? The reason I use rsync is to preserve hard links.

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Re: Local rsync disk to disk slow

Michael Lemke
On Sun, 04 Nov 2018 13:59:34 +0100, Michael Lemke <[hidden email]> wrote:

> I am copying a large directory tree from one internal disk to another USB 3 connected disk on the same computer with this rsync line:
>
> rsync -ahPvzHA --delete /d/Images /q/
>
> This copies files at a rate of 20MB/s. If I copy the same tree with Windows Explorer I get about 90MB/s.

I take this back. Apparently, rsync ins't good at averaging transfer speeds. The files were too small for computing the real transfer rate. For files large enough to take longer to copy rsync computes 90MB/s as well.

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