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Sudden loss of connectivity

Discussion in 'CloudLinux' started by gvard, Apr 20, 2012.

  1. gvard

    gvard Well-Known Member
    PartnerNOC

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    Hello,

    I'm facing a strange issue where the server suddenly loses internet connectivity. The server does not hang, I reboot it with a simple Ctrl-Alt-Del (no hard reset) and when I reboot it the problem gets solved until the next time it appears. I'm writing this issue in case you faced it and solved it without contacting cPanel or CloudLinux, since I contacted both of them and they haven't faced it before.

    About 20 days ago we installed kernel 2.6.18-408.el5.lve0.8.58PAE and on late January we installed kernel 2.6.18-374.12.1.el5.lve0.8.54PAE patched with ksplice. Since late January, on random days and times, the server NIC card becomes unresponsive with no information written on /var/log/messages. When I reboot the server, everything comes back online. The server is rebooted via a single Ctrl+Alt+Del, so the server doesn't hang itself. The issue appeared less with 2.6.18-374.12.1 but was more frequent (about every other day) with 2.6.18-408 kernel.

    The other day I left the server for 5 minutes with "Request timed out" on "ping -t (server IP)" and suddenly I saw the server come back online for 1 minute, got disconnected for 1 minute again, back online for 20 seconds and then I soft rebooted it. When the server came back online, I logged in and saw no load issues, nothing on dmesg and /var/log/messages.

    Is there something strange with kernel 2.6.18-408 or 2.6.18-374.12.1 and r8168 network cards, which wasn't brought up with ksplice patches? Has this been seen by you before? I reverted back to 2.6.18-339.19.1 kernel for the time being with no issues reported up until now (of course patched with ksplice).

    Some output that might help you:

    Code:
    root@de-1 [~]# ethtool -i eth0
    driver: r8168
    version: 8.024.00-NAPI
    firmware-version:
    bus-info: 0000:06:00.0
    root@de-1 [~]# ethtool -S eth0
    NIC statistics:
    tx_packets: 9900980
    rx_packets: 7407719
    tx_errors: 0
    rx_errors: 0
    rx_missed: 0
    align_errors: 0
    tx_single_collisions: 0
    tx_multi_collisions: 0
    unicast: 7407681
    broadcast: 38
    multicast: 0
    tx_aborted: 0
    tx_underrun: 0
    root@de-1 [~]# ethtool -k eth0
    Offload parameters for eth0:
    Cannot get device udp large send offload settings: Operation not supported
    rx-checksumming: on
    tx-checksumming: on
    scatter-gather: off
    tcp segmentation offload: off
    udp fragmentation offload: off
    generic segmentation offload: off
    generic-receive-offload: off
    root@de-1 [~]# 
    
    Also I'd like to point out that I had a cron job run every minute logging the "ifconfig" command to see if the network card was taken offline, but the output logged at the time of the incident is the following (which is similar as the output at the time there is no issue:

    Code:
    Thu Apr 19 23:25:01 EEST 2012
    eth0      Link encap:Ethernet  HWaddr 40:61:86:F3:D9:95
              inet addr:XXXXXX  Bcast:XXXXXX  Mask:255.255.255.255
              inet6 addr: fe80::4261:86ff:fef3:d995/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:122623769 errors:0 dropped:0 overruns:0 frame:0
              TX packets:212375081 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000
              RX bytes:693026835 (660.9 MiB)  TX bytes:3945493725 (3.6 GiB)
              Interrupt:82 Base address:0xc000
    
    eth0:cp1  Link encap:Ethernet  HWaddr 40:61:86:F3:D9:95
              inet addr:XXXXXX  Bcast:XXXXXX  Mask:255.255.255.0
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              Interrupt:82 Base address:0xc000
    
    eth0:cp2  Link encap:Ethernet  HWaddr 40:61:86:F3:D9:95
              inet addr:XXXXXX  Bcast:XXXXXX  Mask:255.255.255.0
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              Interrupt:82 Base address:0xc000
    
    eth0:cp3  Link encap:Ethernet  HWaddr 40:61:86:F3:D9:95
              inet addr:XXXXXX  Bcast:XXXXXX  Mask:255.255.255.0
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              Interrupt:82 Base address:0xc000
    
    lo        Link encap:Local Loopback
              inet addr:127.0.0.1  Mask:255.0.0.0
              inet6 addr: ::1/128 Scope:Host
              UP LOOPBACK RUNNING  MTU:16436  Metric:1
              RX packets:1410530 errors:0 dropped:0 overruns:0 frame:0
              TX packets:1410530 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0
              RX bytes:495445042 (472.4 MiB)  TX bytes:495445042 (472.4 MiB)
    
     

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