如果这些列出命令没有显示任何错误,请使用初始化系统(例如 systemd)查看 Linux 服务器的工作方式。 systemd 是最流行的初始化系统,用于启动用户空间并控制多个系统进程。例如,这是 systemctl status
命令的输出:
-
# systemctl status
-
● bastion.f347.internal
-
State: running
-
Jobs: 0 queued
-
Failed: 0 units
-
Since: Wed 2018-11-28 01:29:05 UTC; 2 days ago
-
CGroup: /
-
├─1 /usr/lib/systemd/systemd --switched-root --system --deserialize 21
-
├─kubepods.slice
-
│ ├─kubepods-pod3881728a_f2af_11e8_af77_06af52f87498.slice
-
│ │ ├─docker-88b27385f4bae77bba834fbd60a61d19026bae13d18eb147783ae27819c34967.scope
-
│ │ │ └─23860 /opt/bridge/bin/bridge --public-dir=/opt/bridge/static --config=/var/console-config/console-c
-
│ │ └─docker-a4433f0d523c7e5bc772ee4db1861e4fa56c4e63a2d48f6bc831458c2ce9fd2d.scope
-
│ │ └─23639 /usr/bin/pod
-
....
深入到各个日志当中
使用 dmesg
可以找出内核最新消息中的错误和警告。例如,这是 dmesg | more
命令的输出:
-
# dmesg | more
-
....
-
[ 1539.027419] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
-
[ 1539.042726] IPv6: ADDRCONF(NETDEV_UP): veth61f37018: link is not ready
-
[ 1539.048706] IPv6: ADDRCONF(NETDEV_CHANGE): veth61f37018: link becomes ready
-
[ 1539.055034] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
-
[ 1539.098550] device veth61f37018 entered promiscuous mode
-
[ 1541.450207] device veth61f37018 left promiscuous mode
-
[ 1542.493266] SELinux: mount invalid. Same superblock, different security settings for (dev mqueue, type mqueue)
-
[ 9965.292788] SELinux: mount invalid. Same superblock, different security settings for (dev mqueue, type mqueue)
-
[ 9965.449401] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
-
[ 9965.462738] IPv6: ADDRCONF(NETDEV_UP): vetheacc333c: link is not ready
-
[ 9965.468942] IPv6: ADDRCONF(NETDEV_CHANGE): vetheacc333c: link becomes ready
-
....
你还可以在 /var/log/messages
文件中查看所有 Linux 系统日志,在该文件中你可以找到与特定问题相关的错误。当你对硬件进行修改(例如安装额外的磁盘或添加以太网网卡)时,通过 tail
命令实时监视消息是值得的。例如,这是 tail -f /var/log/messages
命令的输出:
-
# tail -f /var/log/messages
-
Dec 1 13:20:33 bastion dnsmasq[30201]: using nameserver 127.0.0.1#53 for domain in-addr.arpa
-
Dec 1 13:20:33 bastion dnsmasq[30201]: using nameserver 127.0.0.1#53 for domain cluster.local
-
Dec 1 13:21:03 bastion dnsmasq[30201]: setting upstream servers from DBus
-
Dec 1 13:21:03 bastion dnsmasq[30201]: using nameserver 192.199.0.2#53
-
Dec 1 13:21:03 bastion dnsmasq[30201]: using nameserver 127.0.0.1#53 for domain in-addr.arpa
-
Dec 1 13:21:03 bastion dnsmasq[30201]: using nameserver 127.0.0.1#53 for domain cluster.local
-
Dec 1 13:21:33 bastion dnsmasq[30201]: setting upstream servers from DBus
-
Dec 1 13:21:33 bastion dnsmasq[30201]: using nameserver 192.199.0.2#53
-
Dec 1 13:21:33 bastion dnsmasq[30201]: using nameserver 127.0.0.1#53 for domain in-addr.arpa
-
Dec 1 13:21:33 bastion dnsmasq[30201]: using nameserver 127.0.0.1#53 for domain cluster.local
分析网络功能
你可能有成千上万的云原生应用程序在一个复杂的网络环境中为业务提供服务,其中可能包括虚拟化、多云和混合云。这意味着,作为故障排除的一部分,你应该分析网络连接是否正常工作。弄清 Linux 服务器中网络功能的有用命令包括:ip addr
、traceroute
、nslookup
、dig
和 ping
等。例如,这是 ip addr show
命令的输出:
-
# ip addr show
-
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
-
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
-
inet 127.0.0.1/8 scope host lo
-
valid_lft forever preferred_lft forever
-
inet6 ::1/128 scope host
-
valid_lft forever preferred_lft forever
-
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9001 qdisc mq state UP group default qlen 1000
-
link/ether 06:af:52:f8:74:98 brd ff:ff:ff:ff:ff:ff
-
inet 192.199.0.169/24 brd 192.199.0.255 scope global noprefixroute dynamic eth0
-
valid_lft 3096sec preferred_lft 3096sec
-
inet6 fe80::4af:52ff:fef8:7498/64 scope link
-
valid_lft forever preferred_lft forever
-
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
-
link/ether 02:42:67:fb:1a:a2 brd ff:ff:ff:ff:ff:ff
-
inet 172.17.0.1/16 scope global docker0
-
valid_lft forever preferred_lft forever
-
inet6 fe80::42:67ff:fefb:1aa2/64 scope link
-
valid_lft forever preferred_lft forever
-
....
总结
对 Linux 硬件进行故障排除需要大量的知识,包括如何使用功能强大的命令行工具以及找出系统日志记录。 你还应该知道如何诊断内核空间,在那里你可以找到许多硬件问题的根本原因。请记住,Linux 中的硬件问题可能来自许多不同的来源,包括设备、模块、驱动程序、BIOS、网络,甚至是普通的旧硬件故障。