kernel: [829455.595333][ C10] critical target error, dev sda, sector 104056241 op 0x3:(DISCARD) ......如果是在 VMware 上运行的虚拟机在日志里出现 critical target error 此类报错，尤其是涉及到 DISCARD 操作的错误，通常是由 VMware 进行硬盘垃圾空间回收或者进行硬盘优化造成的。
VMware 的控制平台上，检查宿主机的硬盘是否正常。若不正常则修复或者更换硬盘。
# cat /etc/*release*
NAME="openSUSE Leap"
VERSION="15.4"
ID="opensuse-leap"
ID_LIKE="suse opensuse"
VERSION_ID="15.4"
PRETTY_NAME="openSUSE Leap 15.4"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:opensuse:leap:15.4"
BUG_REPORT_URL="https://bugs.opensuse.org"
HOME_URL="https://www.opensuse.org/"（注意：确保显示的系统版本是 openSUSE Leap 15.4）
# zypper ls -d
# | Alias | Name | Enabled | GPG Check | Refresh | Priority | Type | URI
---+---------------------------+------------------------------------+---------+-----------+---------+----------+--------+---------------------------------------------------------------------------------------------
1 | repo-non-oss | Non-OSS Repository | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/distribution/leap/15.4/repo/non-oss/
2 | repo-oss | Main Repository | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/distribution/leap/15.4/repo/oss/
3 | repo-update | Main Update Repository | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/update/leap/15.4/oss/
4 | repo-update-non-oss | Update Repository (Non-Oss) | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/update/leap/15.4/non-oss/
5 | repo-backports-update | Update repository of openSUSE Backports | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/update/leap/15.4/backports/
6 | repo-sle-update | Update repository with updates from SUSE Linux Enterprise 15 | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/update/leap/15.4/sle/（
补充：
1) 确保以上软件库已处于 Enabled 状态
2) 手动启动这些软件库的命令如下
# zypper ar -fcg http://download.opensuse.org/distribution/leap/${releasever}/repo/non-oss/ Non-OSS Repository
# zypper ar -fcg http://download.opensuse.org/distribution/leap/${releasever}/repo/oss/ Main Repository
# zypper ar -fcg http://download.opensuse.org/update/leap/${releasever}/oss/ Main Update Repository
# zypper ar -fcg http://download.opensuse.org/update/leap/${releasever}/non-oss/ Update Repository (Non-Oss)
# zypper ar -fcg http://download.opensuse.org/update/leap/${releasever}/backports/ Update repository of openSUSE Backports
# zypper ar -fcg http://download.opensuse.org/update/leap/${releasever}/sle/ Update repository with updates from SUSE Linux Enterprise 153) 其中，Main Repository、Main Update Repository、Update repository of openSUSE Backports 和 Update repository with updates from SUSE Linux Enterprise 15 软件库是必须要有的，其他的软件库可以去掉
）
# zypper ref（注意：确保刷新成功，否则请检查网络）
# zypper -n update# sed -i 's/15.4/${releasever}/g' /etc/zypp/repos.d/*.repo# zypper --releasever=15.5 refresh# zypper --releasever=15.5 dup --download-in-advance# zypper --releasever=15.5 dup# reboot# cat /etc/*release*
NAME="openSUSE Leap"
VERSION="15.5"
ID="opensuse-leap"
ID_LIKE="suse opensuse"
VERSION_ID="15.5"
PRETTY_NAME="openSUSE Leap 15.5"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:opensuse:leap:15.5"
BUG_REPORT_URL="https://bugs.opensuse.org"
HOME_URL="https://www.opensuse.org/"# zypper ls -d
# | Alias | Name | Enabled | GPG Check | Refresh | Priority | Type | URI
---+---------------------------+------------------------------------+---------+-----------+---------+----------+--------+---------------------------------------------------------------------------------------------
1 | repo-non-oss | Non-OSS Repository | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/distribution/leap/15.5/repo/non-oss/
2 | repo-oss | Main Repository | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/distribution/leap/15.5/repo/oss/
3 | repo-update | Main Update Repository | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/update/leap/15.5/oss/
4 | repo-update-non-oss | Update Repository (Non-Oss) | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/update/leap/15.5/non-oss/
5 | repo-backports-update | Update repository of openSUSE Backports | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/update/leap/15.5/backports/
6 | repo-sle-update | Update repository with updates from SUSE Linux Enterprise 15 | Yes | (r ) Yes | Yes | 99 | rpm-md | http://download.opensuse.org/update/leap/15.5/sle/（补充：其中，Main Repository、Main Update Repository、Update repository of openSUSE Backports 和 Update repository with updates from SUSE Linux Enterprise 15 软件库是必须要有的，其他的软件库可以去掉）
This Linux server is a virtual server. If we reboot it though its virtual software, there is no relevant logs in the /var/log/messages.
This Linux server is a member of a pacemaker cluster. If the pacemaker cluster software fences this server for protecting the whole cluster, there is no relate logs in the /var/log/messages.
This Linux server has critical problems in its system or hardware. Core panic of Linux and hardware problem both can reboot the system automatically without any reboot logs in the /var/log/messages.
# ip -s -h link# iftop -nN -i eth0（补充：这里以持续查看名为 eth0 网卡的流量为例）
# yum update
Updating Subscription Management repositories.
Unable to read consumer identity# vim /etc/yum/pluginconf.d/subscription-manager.conf将以下内容：
......
[main]
enabled=1
......修改为：
......
[main]
enabled=0
......（步骤略）
（补充：katello-ca-consumer-latest.noarch.rpm 软件包下载自对应的 Red Hat Satellite 服务器，补充链接：Red Hat Satellite client register）