我们有几个运行 VMWare ESXi 4 的服务器，这些服务器上的虚拟机运行着 OpenSUSE 和 Windows 2008r2。我们还有一个使用 OpenNMS 监控这些虚拟机的服务器。对于几个 OpenSUSE 虚拟机，我们会定期收到丢弃数据包百分比的高阈值消息。
检查图表显示，只有传入的包被丢弃。丢弃率最高可达 10%。并非所有 Linux VM 都会发生这种情况。没有发生这种情况的是运行稍旧的 OpenSUSE 11.3 的虚拟机，而其他的是 11.4 或 12.1 的虚拟机，然而，也确实存在此问题的虚拟机负载很小，而负载最重的虚拟机去年丢弃的数据包为零。
Windows 2008 服务器似乎根本没有这个问题。
那么，造成这种情况的可能原因是什么？当比例达到多少时，我应该开始担心？
编辑： 我想知道 snmp 或 opennms 是否显示不正确的数据。当我查看 netstat -s 的输出时，我看到：0 个传入数据包被丢弃
以下是完整的输出（正常运行时间为 137 天）：
Ip:
89907150 total packets received
5047 with invalid addresses
0 forwarded
19748 with unknown protocol
0 incoming packets discarded
89882355 incoming packets delivered
93223508 requests sent out
133 dropped because of missing route Icmp:
4121 ICMP messages received
37 input ICMP message failed.
ICMP input histogram:
destination unreachable: 162
echo requests: 3950
timestamp request: 9
24159 ICMP messages sent
0 ICMP messages failed
ICMP output histogram:
destination unreachable: 20200
echo replies: 3950
timestamp replies: 9 IcmpMsg:
InType3: 162
InType8: 3950
InType13: 9
OutType0: 3950
OutType3: 20200
OutType14: 9 Tcp:
309309 active connections openings
175665 passive connection openings
582 failed connection attempts
19123 connection resets received
27 connections established
89397500 segments received
98178773 segments send out
39585 segments retransmited
7 bad segments received.
256696 resets sent Udp:
448836 packets received
524 packets to unknown port received.
0 packet receive errors
448854 packets sent
RcvbufErrors: 0
SndbufErrors: 0 UdpLite:
InDatagrams: 0
NoPorts: 0
InErrors: 0
OutDatagrams: 0
RcvbufErrors: 0
SndbufErrors: 0 TcpExt:
1897 invalid SYN cookies received
441 resets received for embryonic SYN_RECV sockets
ArpFilter: 0
125024 TCP sockets finished time wait in fast timer
123 packets rejects in established connections because of timestamp
2365891 delayed acks sent
5221 delayed acks further delayed because of locked socket
Quick ack mode was activated 1517 times
76762 packets directly queued to recvmsg prequeue.
32782 packets directly received from backlog
148216 packets directly received from prequeue
81827955 packets header predicted
11453 packets header predicted and directly queued to user
TCPPureAcks: 2002864
TCPHPAcks: 81030906
TCPRenoRecovery: 3
TCPSackRecovery: 5098
TCPSACKReneging: 46
TCPFACKReorder: 31
TCPSACKReorder: 17
TCPRenoReorder: 0
TCPTSReorder: 25
TCPFullUndo: 31
TCPPartialUndo: 599
TCPDSACKUndo: 1712
TCPLossUndo: 691
TCPLoss: 5407
TCPLostRetransmit: 201
TCPRenoFailures: 0
TCPSackFailures: 286
TCPLossFailures: 101
TCPFastRetrans: 11936
TCPForwardRetrans: 493
TCPSlowStartRetrans: 3237
TCPTimeouts: 15424
TCPRenoRecoveryFail: 0
TCPSackRecoveryFail: 165
TCPSchedulerFailed: 0
TCPRcvCollapsed: 0
TCPDSACKOldSent: 1569
TCPDSACKOfoSent: 5
TCPDSACKRecv: 7543
TCPDSACKOfoRecv: 6
TCPAbortOnSyn: 0
TCPAbortOnData: 249150
TCPAbortOnClose: 1391
TCPAbortOnMemory: 0
TCPAbortOnTimeout: 160
TCPAbortOnLinger: 0
TCPAbortFailed: 0
TCPMemoryPressures: 0
TCPSACKDiscard: 15
TCPDSACKIgnoredOld: 2257
TCPDSACKIgnoredNoUndo: 739
TCPSpuriousRTOs: 129
TCPMD5NotFound: 0
TCPMD5Unexpected: 0
TCPSackShifted: 38802
TCPSackMerged: 24929
TCPSackShiftFallback: 16027
TCPBacklogDrop: 0
TCPMinTTLDrop: 0
TCPDeferAcceptDrop: 87963
IPReversePathFilter: 0
TCPTimeWaitOverflow: 0 IpExt:
InNoRoutes: 0
InTruncatedPkts: 0
InMcastPkts: 2
OutMcastPkts: 0
InBcastPkts: 31370
OutBcastPkts: 0
InOctets: 17194554126
OutOctets: 21418612641
InMcastOctets: 72
OutMcastOctets: 0
InBcastOctets: 3492814
OutBcastOctets: 0