~1300ms latency touching file on nfs mount

Asked Sep 28 '18 at 17:01

Active Sep 28 '18 at 17:01

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I have an NFS mount where the server is on the same subnet as the client. When I time touch testempty from the client, I get:

touch testempty  0.00s user 0.00s system 0% cpu 1.325 total

The time follows an bizarre pattern - Most of the time it's just over one second, but approximately once per minute it spikes to around 1.3. See this graph, compiled from time it takes to touch a nonexistent file, once every ten seconds:

graph of latency

When I rm testempty then time touch testempty from the server, I get:

touch testempty  0.00s user 0.00s system 29% cpu 0.005 total

So disk isn't the problem. Ping shows sub-200us latency, so network isn't the problem either. I've found that this still happens when the server mounts its own share.

Here is my /etc/exports:

/data           192.168.0.0/16(rw,no_subtree_check,async,no_root_squash,insecure,sec=sys,fsid=0)
/data/dba_work  192.168.0.0/16(rw,no_subtree_check,async,no_root_squash,insecure,sec=sys,fsid=1)

Any idea what's causing this?

Server is running CentOS 7. Have tried multiple different Linux clients, including the server itself.

asked Sep 28 '18 at 17:01

Dessa Simpson

you can check with wireshark which request are slow. 1.3 sec is tooooo much. – kofemann Oct 20 '18 at 14:50
It sounds like server side processing time and not the network. No network should have 1s or more RTT - heck, not even the Internet across the globe is that bad. – Pedro Perez Oct 23 '18 at 14:53
@PedroPerez As my post said, I am fully aware of that. – Dessa Simpson Oct 23 '18 at 15:05
Not sure how I´ve missed that, apologies! – Pedro Perez Oct 23 '18 at 16:34

~1300ms latency touching file on nfs mount

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