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Re: [Nbd] Performance tuning of nbd !?

Dirk von Suchodoletz wrote:

When I try it over cable (okay, might be a little bit perverted - 25Mbit/s ping of 15ms) or DSL (14Mbit/s ping of 35ms) the results drop to less than 200kByte/sek. It is still possible to run a stateless client that way (squashfs ontop of nbd), but you have to be patient while an app is starting the first time.

Is there any chance to get above the 10Mbit/s LAN rate in the WAN DSL or cable scenarios!?

Yes. I think you should be able to use about 70% of the bandwidth (I can get about 32Mb/s out of 45Mb/s (T3) with 100ms latency). You might need to increase your TCP window size and/or change the I/O scheduler you're using for NBD. Switch to "deadline" scheduler if you're not using that one already. And set the TCP window size, as follows:

In order to raise the window size to about 1 MB, the following sysctl settings should be changed:

net.core.rmem_max = 500000
net.core.wmem_max = 500000
net.ipv4.tcp_rmem = 4096 87380 1333000
net.ipv4.tcp_wmem = 4096 16384 1333000

The window size should be a little above your network "pipe size":

pipe = bandwidth * latency


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