On Wed, Nov 16 at  3:05, Anatoly wrote:
Good day,

The speed of send/recv is around 30-60 MBytes/s for initial send and 17-25 MBytes/s for incremental. I have seen lots of setups with 1 disk to 100+ disks in pool. But the speed doesn't vary in any degree. As I understand 'zfs send' is a limiting factor. I did tests by sending to /dev/null. It worked out too slow and absolutely not scalable. None of cpu/memory/disk activity were in peak load, so there is of room for improvement.

My belief is that initial/incremental may be affecting it because of
initial versus incremental efficiency of the data layout in the pools,
not because of something inherent in the send/recv process itself.

There are various send/recv improvements (e.g. don't use SSH as a
tunnel) but even that shouldn't be capping you at 17MBytes/sec.

My incrementals get me ~35MB/s consistently.  Each incremental is
10-50GB worth of transfer.

cheap gig switch, no jumbo frames
Source = 2 mirrored vdevs + l2arc ssd, CPU = xeon E5520, 6GB RAM
Destination = 4-drive raidz1, CPU = c2d E4500 @2.2GHz, 2GB RAM
tunnel is un-tuned SSH

I found these guys have the same result - around 7 Mbytes/s for 'send' and 70 Mbytes for 'recv'.

Their data doesn't match mine.

Eric D. Mudama

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