[OpenIndiana-discuss] ZFS remote receive

Sebastian Gabler sequoiamobil at gmx.net
Wed Oct 31 09:58:19 UTC 2012

> Message: 7
> Date: Tue, 30 Oct 2012 22:03:13 +0400
> From: Jim Klimov<jimklimov at cos.ru>
> To: Discussion list for OpenIndiana
> 	<openindiana-discuss at openindiana.org>
> Subject:
> Message-ID:<50901661.9050606 at cos.ru>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 2012-10-30 19:21, Sebastian Gabler wrote:
>> >Whereas that's relative: performance is still at a quite miserable 62
>> >MB/s through a gigabit link. Apparently, my environment has room for
>> >improvement.
> Does your gigabit ethernet use Jumbo Frames (like 9000 or up to 16KB,
> depending on your NICs, switches and other networking gear) for
> unrouted (L2) storage links? It is said that traditional MTU=1500
> has too many overheads with packet size and preamble delays between
> packets that effectively limit a gigabit to 700-800Mbps...
> //Jim
> ------------------------------
The MTU is on 1500 on source and target system, and there are no 
fragmentations happening. On the target system I am seeing writes up to 
160 MB/s with frequent zpool iostat probes. When iostat probes are up to 
5s+, there is a steady stream of 62 MB/s. At this time I am not sure if 
that is indeed a networking issue. I am also not sure how jumbo frames 
could provide an intersting benefit here. The usually alleged 15% (which 
are already on the high side) are not in the scope of making or breaking 
the use case.



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