-[Failed to Compile MariaDB Using rpmbuild](#failed-to-compile-mariadb-using-rpmbuild)
-[Failed to Start the SNTP Service Using the Default Configuration](#failed-to-start-the-sntp-service-using-the-default-configuration)
-[Installation Failure Caused by Software Package Conflict, File Conflict, or Missing Software Package](#installation-failure-caused-by-software-package-conflict-file-conflict-or-missing-software-package)
-[Why Do OpenSSH-related Packages Fail to Be Installed when the OpenSSH Software Package Is Upgraded in Default DNF Update Mode?](#Why-Do-OpenSSH-related-Packages-Fail-to-Be-Installed-when-the-OpenSSH-Software-Package-Is-Upgraded-in-Default-DNF-Update-Mode)
<!-- /TOC -->
## Why Is the Memory Usage of the libvirtd Service Queried by Running the systemctl and top Commands Different?
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@@ -162,3 +163,32 @@ If a software package is missing, perform the following steps \(the missed softw
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3. Perform the upgrade again.
## Why Do OpenSSH-related Packages Fail to Be Installed when the OpenSSH Software Package Is Upgraded in Default DNF Update Mode?
### Symptom
When the OpenSSH software package is upgraded in default DNF update mode, a message indicating that the OpenSSH-related packages cannot be installed is displayed as follows:
```
cannot install both openssh-7.8p1-8.oe1.aarch64 and openssh-8.2p1-5.oe1.aarch64
cannot install both openssh-7.8p1-8.oe1.aarch64 and openssh-8.2p1-4.oe1.aarch64
cannot install the best update condidate for package openssh-clients-8.2p1-5.oe1.aarch64
cannot install the best update condidate for package openssh-8.2p1-5.oe1.aarch64
```
### Possible Cause
By default, the best mode of the DNF package manager (the corresponding parameter is **--best**) is enabled. The **--best** option for DNF always tries to upgrade to the latest version available even if dependencies cannot be satisfied. By enabling the DNF best mode by default, the user will be reminded that a later package version is available but it fails to satisfy the dependencies. If a problem occurs, the DNF displays a message to notify the user of the problem. The openEuler Community developers are looking to make this default setting change in case that a security fix package cannot be upgraded due to dependency issues, under the current premise that it could be silently ignored and the user would not be aware. In addition, using the DNF best mode will quickly alert developers to problems in upgrade paths.
### Solution
A **--nobest** option for DNF will be available to override or disable the default behavior, allowing the user to properly upgrade the security fix package when the package to be upgraded has dependency issues.
Open source software developers of openEuler 20.03-LTS have identified this scenario during the upgrade of the security fix version of the OpenSSH software package. It is recommended that users select a proper upgrade mode based on the preceding analysis. openEuler also provides users with specific instructions on the upgrade operation:
