[Samba] Re: CTDB + Samba: Tune Read Performance

Volker Lendecke Volker.Lendecke at SerNet.DE
Fri Jan 30 21:52:50 GMT 2009

On Fri, Jan 30, 2009 at 02:34:27PM -0700, tim clusters wrote:
> Currently, a SMB server is able to handle sustained 300MB/s on writes and
> 200MB/s on reads. Performance remains constant as you scale clients with no
> time-outs and performance scales as you add another server. Iam still not
> sure if we can extract more from SMBD as CPU/memory/IO subsystem is less
> than 30% saturated. Seems like the performance bottleneck is network-related
> + SMB packet-size as raw network yields 450MB/s for 64KB packet-size.

Not having followed what you already tried, but I can assure
you that smbd is not the bottleneck for the raw transfer
tests. Just this week I was at a customer with 10GigE.
Tested a get operation with smbclient from master. First run
120MB/sec. Increased window size, got around 300MB/sec.
Activated jumbo frames, got around 600MB/sec. To get this,
we had to make sure the file was already in RAM. It seemed
that above 450MB/sec the file system (ZFS on top of some SAN
with 192 disks in that case) started to be the bottleneck.

With pure netcat we got a difference of less than 5%,
definitely below the normal variation.

I'm stressing the use of latest smbclient a bit, because
this should really squeeze what you cat get out of your
hardware, it completely the network latencies.

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