zfs send/receive: is this slow?

[Sean]

On 02/10/2010, at 11:43 AM, Artem Belevich wrote:

>> As soon as I opened this email I knew what it would say.
>> 
>> 
>> # time zfs send storage/bacula at transfer | mbuffer | zfs receive
>> storage/compressed/bacula-mbuffer
>> in @  197 MB/s, out @  205 MB/s, 1749 MB total, buffer   0% full
> ..
>> Big difference.  :)
> 
> I'm glad it helped.
> 
> Does anyone know why sending/receiving stuff via loopback is so much
> slower compared to pipe?


Up and down the entire network stack, in and out of TCP buffers at both ends... might add some overhead, and other factors in limiting it.

Increasing TCP buffers, and disabling delayed acks might help. Nagle might also have to be disabled too. (delayed acks and nagle in combination can interact in odd ways)


> 
> --Artem
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