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由于DNS查询失败、客户端自动挂载偶尔会失败

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适用场景

机载DNS负载平衡
 

问题描述

  • 在挂载风暴环境中、绑定版本等于或大于 bind-9.9.9.4-69.el7 且开始支持 0 TTL的外部Linux DNS服务器 可能会将DNS查询请求转发到非侦听器机载DNS服务器LIF
  • 如果外部DNS服务器将DNS查询请求转发给非侦听器机载DNS服务器LIF、则ONTAP 会拒绝初始连接请求
  • 最终会导致客户端DNS查询失败
 
示例：
 
//IP信息
 
NFS客户端：
192.168.0.61
外部DNS服务器IP：
192.168.0.188
存储IP：
192.168.0.134
192.168.0.135 (仅允许使用此IP来处理DNS查询请求。listen-for-dns-query:true)
192.168.0.136
192.168.0.137
192.168.0.139
 
//OTNAP配置
 
cluster1::*> net int show -vserver svm2_cluster1 -fields listen-for-dns-query,dns-zone,address
(network interface show)
vserver  lif   address  dns-zone  listen-for-dns-query
------------- --------------------- ------------- ----------------------- --------------------
svm2_cluster1 lif_svm2_cluster1_433 192.168.0.135 storage_hostname.test.com true
svm2_cluster1 lif_svm2_cluster1_453 192.168.0.137 storage_hostname.test.com false
svm2_cluster1 lif_svm2_cluster1_583 192.168.0.134 storage_hostname.test.com false
svm2_cluster1 lif_svm2_cluster1_858 192.168.0.136 storage_hostname.test.com false
svm2_cluster1 lif_svm2_cluster1_996 192.168.0.139 storage_hostname.test.com false
 
///分区文件配置
 
/var/named/test.zone
------------------------------------------
;TR guide setting
$ORIGIN storage_hostname.com.
@   IN   NS   storage_hostname.com.
IN   NS   ansible.seccae.com.
storage_hostname.test.com.  IN   A  192.168.0.135
 

///日志分析

NFS客户端返回SERVERFAIL错误和自动挂载失败消息 

Sun Jun 26 15:14:06 UTC 2022
storage_hostname.test.com has address 192.168.0.134
Host storage_hostname.test.com not found: 2(SERVFAIL)
Host storage_hostname.test.com not found: 2(SERVFAIL)
Sun Jun 26 15:14:07 UTC 2022
Host storage_hostname.test.com not found: 2(SERVFAIL)

May 9 07:55:12 client_hostname automount[1364] : add_host_addrs: hostname lookup for storage_hostname failed: Name or service not known

外部DNS服务器从 named.run日志返回连接被拒绝的信息级别消息

6-Jun-2022 15:10:02.301 resolver: debug 1: fetch: storage_hostname.test.com/AAAA
26-Jun-2022 15:10:02.335 resolver: debug 1: fetch: storage_hostname.test.com/MX
26-Jun-2022 15:14:06.990 resolver: debug 1: fetch: storage_hostname.test.com/A
26-Jun-2022 15:14:07.004 resolver: debug 1: fetch: storage_hostname.test.com/AAAA
26-Jun-2022 15:14:07.005 lame-servers: info: connection refused resolving 'storage_hostname.test.com/AAAA/IN': 192.168.0.134#5326-Jun-2022 15:14:07.005 resolver: debug 1: fetch: storage_hostname.test.com/AAAA
26-Jun-2022 15:14:07.005 query-errors: debug 1: client @0x7f5362edac20 192.168.0.61#60563 (storage_hostname.test.com): query failed (SERVFAIL) for storage_hostname.test.com/IN/AAAA at ../../../bin/named/query.c:8580
26-Jun-2022 15:14:07.005 lame-servers: debug 1: lame server resolving 'storage_hostname.test.com' (in 'storage_hostname.test.com'?): 192.168.0.188#53
26-Jun-2022 15:14:07.005 resolver: debug 1: fetch: storage_hostname.test.com/MX
26-Jun-2022 15:14:07.006 lame-servers: info: connection refused resolving 'storage_hostname.test.com/AAAA/IN': 192.168.0.134#53
26-Jun-2022 15:14:07.006 lame-servers: info: connection refused resolving 'storage_hostname.test.com/MX/IN': 192.168.0.134#53
26-Jun-2022 15:14:07.006 query-errors: debug 1: client @0x7f53600aa070 192.168.0.61#57471 (storage_hostname.test.com): query failed (SERVFAIL) for storage_hostname.test.com/IN/MX at ../../../bin/named/query.c:8580
26-Jun-2022 15:14:07.017 resolver: debug 1: fetch: storage_hostname.test.com/A
26-Jun-2022 15:14:07.017 lame-servers: info: connection refused resolving 'storage_hostname.test.com/A/IN': 192.168.0.134#53
26-Jun-2022 15:14:07.017 query-errors: debug 1: client @0x7f5362edac20 192.168.0.61#48698 (storage_hostname.test.com): query failed (SERVFAIL) for storage_hostname.test.com/IN/A at ../../../bin/named/query.c:8580

存储端pakcet跟踪在
此处清楚地记录了此行为、只有192.168.0.135是机载DNS列表程序IP

72   2022-06-26 23:14:19.572835   6.154698   192.168.0.188   38078    192.168.0.135   53   DNS   Standard query 0x1d9c A storage_hostname.test.com OPT
73   2022-06-26 23:14:19.585266   0.012431   192.168.0.135   53   192.168.0.188   38078   DNS   Standard query response 0x1d9c A storage_hostname.test.com A 192.168.0.134 NS storage_hostname.test.com OPT
74   2022-06-26 23:14:19.586980   0.001714   192.168.0.188   33860    192.168.0.134   53   DNS   Standard query 0x88a9 AAAA storage_hostname.test.com OPT
75   2022-06-26 23:14:19.587027   0.000047   192.168.0.134   33860    192.168.0.188   53   ICMP   Destination unreachable (Port unreachable)

可以通过从外部DNS服务器捕获的数据包跟踪检查完整行为

  • 查询成功
    • 客户端向外部DNS服务器发送查询请求
    • 外部DNS服务器将此查询请求转发到机载DNS IP 192.168.0.135
    • 对外部DNS服务器发出查询响应的机载DNS回复(此时、外部DNS服务器似乎记住IP 192.168.0.134)
    • 外部DNS服务器使用查询响应响应响应客户端(使用192.168.0.134挂载存储系统)
  • AAAA查询失败
    • 客户端向外部DNS服务器发送AAAA查询请求
    • 外部DNS服务器将此AAAA查询请求转发到机载DNS IP 192.168.0.134
    • 机载DNS回复 Destination unreachable 到外部DNS服务器
    • 外部DNS服务器使用响应客户端 query failed (SERVFAIL)
  • MX查询失败
    • 客户端向外部DNS服务器发送MX查询请求
    • 外部DNS服务器将此MX查询请求转发到机载DNS IP 192.168.0.134
    • 机载DNS回复 Destination unreachable 到外部DNS服务器
    • 外部DNS服务器使用响应客户端 query failed (SERVFAIL)
  • 查询失败
    • 客户端向外部DNS服务器发送查询请求
    • 外部DNS服务器将此查询请求转发到机载DNS IP 192.168.0.134
    • 机载DNS回复 Destination unreachable 到外部DNS服务器
    • 外部DNS服务器使用响应客户端 query failed (SERVFAIL)

967   2022-06-26 23:14:06.989631   0.000501   192.168.0.61   36365    192.168.0.188   53   DNS   Standard query 0x6fea A storage_hostname.test.com
969   2022-06-26 23:14:06.990708   0.000557   192.168.0.188   38078    192.168.0.135   53   DNS   Standard query 0x1d9c A storage_hostname.test.com OPT
970   2022-06-26 23:14:07.003287   0.012579   192.168.0.135   53   192.168.0.188   38078    DNS   Standard query response 0x1d9c A storage_hostname.test.com A 192.168.0.134 NS storage_hostname.test.com OPT
971   2022-06-26 23:14:07.003852   0.000565   192.168.0.188   53   192.168.0.61   36365    DNS   Standard query response 0x6fea A storage_hostname.test.com A 192.168.0.134 NS storage_hostname.test.com
972   2022-06-26 23:14:07.004491   0.000639   192.168.0.61   60563    192.168.0.188   53   DNS   Standard query 0x47bc AAAA storage_hostname.test.com
973   2022-06-26 23:14:07.004892   0.000401   192.168.0.188   33860    192.168.0.134   53   DNS   Standard query 0x88a9 AAAA storage_hostname.test.com OPT
974   2022-06-26 23:14:07.005017   0.000125   192.168.0.134   33860    192.168.0.188   53   ICMP   Destination unreachable (Port unreachable)
975   2022-06-26 23:14:07.005451   0.000434   192.168.0.188   53   192.168.0.61   60563    DNS   Standard query response 0x47bc Server failure AAAA storage_hostname.test.com
976   2022-06-26 23:14:07.005710   0.000259   192.168.0.61   57471    192.168.0.188   53   DNS   Standard query 0xe348 MX storage_hostname.test.com
977   2022-06-26 23:14:07.005742   0.000032   192.168.0.188   59080    192.168.0.134   53   DNS   Standard query 0xde2d AAAA storage_hostname.test.com OPT
978   2022-06-26 23:14:07.005809   0.000067   192.168.0.134   59080    192.168.0.188   53   ICMP   Destination unreachable (Port unreachable)
979   2022-06-26 23:14:07.005901   0.000092   192.168.0.188   51515    192.168.0.134   53   DNS   Standard query 0x0a65 MX storage_hostname.test.com OPT
980   2022-06-26 23:14:07.005999   0.000098   192.168.0.134   51515    192.168.0.188   53   ICMP   Destination unreachable (Port unreachable)
981   2022-06-26 23:14:07.006199   0.000200   192.168.0.188   53   192.168.0.61   57471    DNS   Standard query response 0xe348 Server failure MX storage_hostname.test.com
982   2022-06-26 23:14:07.016776   0.010577   192.168.0.61   48698    192.168.0.188   53   DNS   Standard query 0x573a A storage_hostname.test.com
983   2022-06-26 23:14:07.017217   0.000441   192.168.0.188   46874    192.168.0.134   53   DNS   Standard query 0xf57a A storage_hostname.test.com OPT
984   2022-06-26 23:14:07.017343   0.000126   192.168.0.134   46874    192.168.0.188   53   ICMP   Destination unreachable (Port unreachable)
985   2022-06-26 23:14:07.017536   0.000193   192.168.0.188   53   192.168.0.61   48698    DNS   Standard query response 0x573a Server failure A storage_hostname.test.com
987   2022-06-26 23:14:07.027914   0.010016   192.168.0.61   53770    192.168.0.188   53   DNS   Standard query 0x4a57 A storage_hostname.test.com
989   2022-06-26 23:14:07.028215   0.000217   192.168.0.188   53   192.168.0.61   53770    DNS   Standard query response 0x4a57 Server failure A storage_hostname.test.com
995   2022-06-26 23:14:07.038529   0.009511   192.168.0.61   41057    192.168.0.188   53   DNS   Standard query 0x498a A storage_hostname.test.com
996   2022-06-26 23:14:07.038756   0.000227   192.168.0.188   53   192.168.0.61   41057    DNS   Standard query response 0x498a Server failure A storage_hostname.test.com

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