Clean, Cold, and Warm Booting (Windows Embedded CE 6.0)
1/6/2010
There are several types of boot processes: clean, cold, and warm. They differ in the following ways:
- Clean booting clears all memory, including persistent storage.
- Cold booting clears both program memory and storage memory, the object store.
- Warm booting clears program memory, and keeps storage memory.
The following table presents the results for the different types.
| Type of Boot | Device Uses the Object Store? | Program Memory | Object Store | Persistent Storage | User Data |
|---|---|---|---|---|---|
Clean |
Yes |
Cleared |
Cleared |
Cleared, except removable storage. |
Lost |
|
No |
Cleared |
NA |
Cleared, except removable storage. |
Lost |
Cold |
Yes |
Cleared |
Cleared |
Retained |
Lost |
|
No |
Cleared |
NA |
Retained |
Lost |
Warm |
Yes |
Cleared |
Retained |
Retained |
Retained |
|
No |
Cleared |
NA |
Retained |
Lost |
- Program memory is typically volatile RAM, or RAM that requires power to store data. Turning the device off erases program memory.
- Storage memory is nonvolatile RAM (NVRAM), or RAM that does not require power to store data. Turning off the power does not affect storage memory.
- Persistent storage can be any type of nonvolatile storage, either RAM, ROM, or a hard drive. Turning off the power does not affect the persistent storage.
The OEM must ensure that their device maps the underlying functions to whether the device uses the object store.
Historically, a warm boot occurred when a control key was pressed to reload the OS without shutting down the power. This is technically inaccurate for most mobile devices that power down to reload. In older devices, powering down meant loss of data, and sometimes required a complicated power-on procedure. Those problems are irrelevant to a mobile device that does not lose any data when turned off, but the terminology persists.
In earlier systems, the data was stored in the object store. A warm boot retained user data, and cold boots lost their data. Cold boots were the same as clean boots.
**If for some reason there is a problem, and you need to wipe all of your data back to a factory reset, you want to make the device clean boot. OEMs design a way to wipe the device, if necessary. Otherwise, the device performs a clean boot on its first boot, and cold boots after that unless the user does something special to force another clean boot. It looks like a warm boot because the data persists.
For general Windows Embedded CE devices, all three options (clean, cold, and warm) are still possible. It depends on whether there is any user data stored in the object store.
Persistent means data that is not erased when you turn off power. So, removable storage cards are also considered persistent. However, the registry would not normally be on a storage card, or at the root file system because the device cannot function without it. The persistent store is generally a non-removable storage device.
A clean boot should never wipe removable storage, but in some cases people might want the option to do so. For example, if they want to delete all data from the device for security purposes, to prevent it from falling into the wrong hands. In that case you might want to also wipe the storage card, if there is one. Typically, a clean boot is considered one in which all settings and files that the OS uses go back to their factory default settings.