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How to Boot Oracle Linux 7 into Rescue and Emergency Modes via systemd (Doc ID 2153996.1)

Last updated on JUNE 23, 2021

Applies to:

Oracle Cloud Infrastructure - Version N/A and later
Linux OS - Version Oracle Linux 7.0 and later
Linux x86-64

Goal

This article describes how to configure Oracle Linux 7 (OL7) to boot into rescue and emergency modes.

In OL7, both rescue mode and emergency mode are systemd targets (that replace runlevels of previous OL versions).

Rescue mode is equivalent to single user mode and requires the root password.

Rescue mode allows the system to be repaired in situations when it is unable to complete it's regular boot process. Rescue mode attempts to mount all local filesystems and start important system services, however does not activate network interfaces, nor allow multiple users to be logged in.

Emergency mode provides a minimal environment allowing the system to be repaired even in situations when the system is unable to enter rescue mode. In emergency mode, the system mounts the root file system as read-only, does not attempt to mount other local fileystems and does not activate network interfaces.

In the event that Oracle Linux is unable to completely boot at all, refer to How to Bootup Oracle Linux 7.x into Rescue Mode From ISO Image.

Solution

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In this Document
Goal
Solution
 Booting into Emergency mode (target)
 Booting into Rescue mode (target)
 Booting to systemd Debug Shell
 Switching to Emergency mode (target)
 Switching to Rescue mode (target)
References

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