Boot Modes

Boot modes

The boot mode determines whether MiniOS starts cleanly, opens a saved session, or runs as a conventional installed system. You do not need to understand the internal boot process to make this choice.

Menu labels can differ slightly between releases, firmware modes, and boot tools. Choose by the result you need rather than by the exact wording.

Quick choice

The normal default entry is Start MiniOS. It uses automatic persistence selection: MiniOS tries to resume a compatible default session and can create a compatible replacement when no usable session exists and suitable writable storage is available.

Menu entry	Use it when	Are changes saved?	Keep the USB connected?
Start MiniOS (default)	Normal portable use	Yes, if automatic persistence activation succeeds	Yes
Start a new session	You want a separate new workspace	Only if the new session is created and activated successfully	Yes
Choose a saved session	You want to select one of several existing workspaces	Only if the selected session activates successfully	Yes
Start without saving	You want a clean temporary boot without persistence	No	Yes
Run from RAM	You want to copy MiniOS system data into RAM for this boot	RAM-backed changes are temporary unless a supported persistence session is explicitly saved back or saved as new	Until MiniOS has successfully detached the source and any storage you still need

For a normal first boot, leave Start MiniOS selected. Use Start without saving when you specifically need a clean temporary hardware test or recovery session that must not open or create persistence.

::: warning Confirm that persistence is active Choosing a persistent menu entry requests a session; it does not guarantee that the session can be opened. If storage is read-only, full, damaged, or incompatible, MiniOS can continue without saving changes. Check the startup warning before beginning work that must be retained. :::

Start MiniOS

Start MiniOS is the first and default menu entry. It is intended for normal use, including the first boot of a newly prepared MiniOS device.

MiniOS automatically looks for a compatible persistent session. If a usable default session exists, it resumes that session. If none exists, MiniOS can create a compatible session automatically when suitable writable storage is available.

If persistence cannot be created or activated because the storage is read-only, full, damaged, or otherwise unsuitable, MiniOS continues with a temporary writable layer and reports that the session is not persistent. Check that warning before doing work that must survive a reboot.

For a working persistent session, MiniOS Configurator can keep selected ordinary logs and caches in RAM while retaining boot diagnostics and user data on storage. The three settings and their RAM limits are described under Performance. They have no effect on a Start without saving boot.

Start a new session

MiniOS opens the persistence setup menu, lets you choose a supported storage backend and applicable encryption or DynBlk compression options, then creates an additional numbered persistent session while leaving existing sessions unchanged. This is the current perchdir=setup behavior. Use it to keep separate workspaces or to test a new configuration without replacing your current working session.

Creation requires writable compatible storage and enough free space. The available backend choices depend on the filesystem, Secure Boot state, installed drivers/tools, and initrd capabilities. A new session is not a backup of an existing one.

Choose a saved session

MiniOS displays available saved sessions and lets you select one. Use this when one device contains several workspaces. If the selected persistence store is empty, the ask path automatically enters persistence setup so you can create the first session.

A session can be incompatible when it comes from another MiniOS release or edition. A different union= setting can also make a session incompatible. Interactive selection does not make an incompatible session safe.

The incompatibility dialog can reset system-installed software while keeping data and, optionally, system settings. Both reset modes preserve home folders, personal settings, accounts, and passwords. They need free space to stage retained data; a SquashFS reset becomes permanent only after saving. See Session management before using reset.

Start without saving

This mode deliberately disables persistence for the current boot. MiniOS uses a temporary writable area in RAM, so files created in the live system, installed packages, and changed settings disappear at shutdown.

Use this mode when you specifically want to:

• test hardware without opening or creating a persistent session;
• diagnose a problem without changing saved state;
• work temporarily when nothing needs to be retained.

Starting without saving does not mean that the boot medium can be removed. The running system normally continues reading its system modules from that medium.

Run from RAM

This mode copies MiniOS system data into RAM to reduce reads from the source. It needs enough memory for the copied system and the running workload.

System copying and persistence copying are separate. With a persistence request, toram defaults perchtoram to trim, so the selected supported Raw, DynFileFS, DynBlk, VMDK, or SquashFS session is copied into RAM while unrelated saved sessions stay on the original store. Use perchtoram=off when you want the system in RAM but the active persistence session to keep writing directly to storage, or perchtoram=full when all supported stored sessions should be copied. Native directory data is not copied: a successful native RAM request starts a new empty container instead. During a native-session reset, copying is disabled to preserve retained data. If a session copy lacks memory or fails, MiniOS reports the fallback and keeps the session on storage.

A RAM-backed persistence session is non-durable while it is running. Current MiniOS Session Manager can explicitly write supported RAM-backed changes back to the original store with Save Now, or save them as a new numbered session, provided the original store is present, writable, and still matches the identity recorded at boot. Until such a save succeeds, unsaved RAM changes are lost at shutdown. SquashFS automatic save policies use the same session backend when the original store is available.

Do not remove the boot device merely because Run from RAM was selected. It is safe only after MiniOS has successfully detached the source filesystem, ISO loop, Ventoy mappings, and any persistence dependency you still need. If detachment fails, the source remains in use.

Ventoy persistence images

With a selected Ventoy Persistence Plugin backend, a persistent boot uses one writable ext4 environment from that image instead of numbered MiniOS sessions. Start a new session and Choose a saved session cannot create or select numbered sessions in this mode; select another backend in Ventoy instead. Session Manager and perchtoram are unavailable, so even a system RAM boot keeps the image in use. Start without saving still uses a temporary RAM upper. Ordinary Ventoy boots without a selected plugin image keep normal MiniOS session behavior. See Ventoy.

Native installation

::: warning Native installation changes the system model A native installation keeps the familiar MiniOS desktop experience — its visual identity, selected desktop environment, and ordinary applications — but converts the live image into a conventional Debian desktop. MiniOS-specific tools for sessions, modules, modular kernels, and other live workflows are removed because those features no longer apply. :::

After native conversion, use the normal Debian package, kernel, configuration, and bootloader tools. The result remains visually familiar and keeps the ordinary desktop applications from the selected edition, but the MiniOS-specific live feature set is no longer present. The MiniOS live architecture is described in About MiniOS.

Use MiniOS Installer only when you deliberately want that conversion and the selected image supports native deployment.

When you need more detail

• Boot menus explains navigation and temporary editing of a menu entry.
• Session management explains storage modes, session creation, resizing, and removal.
• Boot parameters is the complete command-line reference.
• Initrd system discovery, module loading, and persistence explain how the related parameter groups are processed during startup.