On 4/24/14, 10:22 AM, Cedric Blancher wrote:
On 24 April 2014 05:12, Jim Rees <rees@xxxxxxxxx> wrote:
Cedric Blancher wrote:
Are there any options to improve the Linux NFSv4 performance over a
high latency connection?
We did some work along these lines at CITI years ago. As I remember, the
main thing was to increase net.ipv4.tcp_[rw]mem on the server side, because
tcp auto-tuning was being defeated. This may be less of an issue with your
work load, which sounds like many small files rather than one big one. In
theory, NFSv4 delegations should help, but I don't know how well that works.
Along with Jim's work, we followed up with a fair bit, but in general we
found that nfs clients just can't do well over large rtt due to the slow
window ramp up time and adverse reaction to packet loss. Unfortunately
the only way to overcome these issues (other than using a custom udp
protocol which isn't supported) is to use multiple TCP connections,
which is what we do by using multiple nodes....
I have some basic instructions here on what we do in our environments:
http://researcher.watson.ibm.com/researcher/view_person_subpage.php?id=4427
Dean
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