Hi, Am 02.01.2018 um 15:20 schrieb Wei Xu: > On Tue, Jan 02, 2018 at 12:17:29PM +0100, Stefan Priebe - Profihost AG wrote: >> Hello, >> >> currently i'm trying to fix a problem where we have "random" missing >> packets. >> >> We're doing an ssh connect from machine a to machine b every 5 minutes >> via rsync and ssh. >> >> Sometimes it happens that we get this cron message: >> "Connection to 192.168.0.2 closed by remote host. >> rsync: connection unexpectedly closed (0 bytes received so far) [sender] >> rsync error: unexplained error (code 255) at io.c(226) [sender=3.1.2] >> ssh: connect to host 192.168.0.2 port 22: Connection refused" > > Hi Stefan, > What kind of virtio-net backend are you using? Can you paste your qemu > command line here?
Sure netdev part: -netdev type=tap,id=net0,ifname=tap317i0,script=/var/lib/qemu-server/pve-bridge,downscript=/var/lib/qemu-server/pve-bridgedown,vhost=on -device virtio-net-pci,mac=EA:37:42:5C:F3:33,netdev=net0,bus=pci.0,addr=0x12,id=net0,bootindex=300 -netdev type=tap,id=net1,ifname=tap317i1,script=/var/lib/qemu-server/pve-bridge,downscript=/var/lib/qemu-server/pve-bridgedown,vhost=on,queues=4 -device virtio-net-pci,mac=6A:8E:74:45:1A:0B,nedev=net1,bus=pci.0,addr=0x13,id=net1,vectors=10,mq=on,bootindex=301 > 'Connection refused' usually means that the client gets a TCP Reset rather > than losing packets, so this might not be a relevant issue. Mhm so you mean these might be two seperate ones? > Also you can do a tcpdump on both guests and see what happened to SSH packets > (tcpdump -i tapXXX port 22). Sadly not as there's too much traffic on that part as rsync is syncing every 5 minutes through ssh. >> The tap devices on the target vm shows dropped RX packages on BOTH tap >> interfaces - strangely with the same amount of pkts? >> >> # ifconfig tap317i0; ifconfig tap317i1 >> tap317i0 Link encap:Ethernet HWaddr 6e:cb:65:94:bb:bf >> UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 >> RX packets:2238445 errors:0 dropped:13159 overruns:0 frame:0 >> TX packets:9655853 errors:0 dropped:0 overruns:0 carrier:0 >> collisions:0 txqueuelen:1000 >> RX bytes:177991267 (169.7 MiB) TX bytes:910412749 (868.2 MiB) >> >> tap317i1 Link encap:Ethernet HWaddr 96:f8:b5:d0:9a:07 >> UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 >> RX packets:1516085 errors:0 dropped:13159 overruns:0 frame:0 >> TX packets:1446964 errors:0 dropped:0 overruns:0 carrier:0 >> collisions:0 txqueuelen:1000 >> RX bytes:1597564313 (1.4 GiB) TX bytes:3517734365 (3.2 GiB) >> >> Any ideas how to inspect this issue? > > It seems both tap interfaces lose RX pkts, dropping pkts of RX means the > host(backend) cann't receive packets from the guest as fast as the guest > sends. Inside the guest i see no dropped packets at all. It's only on the host and strangely on both taps at the same value? And both are connected to absolutely different networks. > Are you running some symmetrical test on both guests? No. Stefan > Wei > >> >> Greets, >> Stefan >>