Conserving Battery Power with Ubuntu Netbooks: Suspend Vs. Hibernate

Netbooks and other small computing devices have seen improved battery technology being integrated into their systems. They also have less power hungry components, like hard drives, monitors, and Central Processing Units (CPUs). These technological improvements provide these devices with longer usage times between battery charges. Many netbooks are running 6 cell batteries that can last for up to six hours, or more.

Modern operating systems that use hibernate and suspend utilities can extend that battery life to a full day or more. These utilities are found in Windows 7, Ubuntu Linux, and Apple's OSX. These power saving features work out of the box for computers running Windows and Mac's OSX. However, for open source software, like Ubuntu and other distributions of Linux you may have to search around to find the right hardware that takes advantage of the sleep and hibernate utilities.

Choose the Best Netbook for Ubuntu
Ubuntu Linux suspend and hibernate features in laptops and netbooks may not work with some computers. Ubuntu support forums are chock full of users complaining that suspend and hibernate is not working correctly. Sometimes a computer hardware settings are just not compatible with Linux. This may be especially true for older hardware, as Linux kernel developers are striving to remain current with more modern hardware, and older systems are being left behind.

For newer hardware, fixing suspend and hibernate may come down to adjusting the settings that the default version of the Advanced Configuration and Power Interface (ACPI) uses. You may find a quick solution to some suspend and hibernate problems that only involve a minor change how the Linux Kernel boots. Other times you may simply need an update your netbook or laptop bios software. Then again, sometimes ACPI cannot be fixed, and you may be left with a netbook or laptop that does not allow suspend or hibernate to work. If you want to make sure that suspend and hibernate work for your Ubuntu Linux system, be sure to do a little research on the hardware you plan to buy a system.

If you looking to make new purchase of a netbook or laptop, and plan to run Ubuntu Linux on it, then one of you first criteria for selection should be to make sure the the ACPI functionality is fully supported. If suspend and hibernate are fully functional, then you will be able to get the most out of your battery.

So what is ACPI, and what does it have to do with Suspend and Hibernate?
The Advanced Configuration and Power Interface is a program that acts as an interface between the software and hardware. It is an interface that modern devices use to control specific the power settings withing the hardware. ACPI 'talks' to hardware and tells it when to turn on, turn off, etc. ACPI can also control individual pieces of hardware within your computer and tell it to when turn off. For example, ACPI can tell your hard drive to spin up or down or turn on your video card to wake up your monitor.

All of the major computer operating systems uses some form of ACPI for control. You find ACPI in one form or another in Windows, Mac OSX, Linux, and Unix operating systems. ACPI is also present in many embedded technologies like cell phones. ACPI is able to accommodate all of these devices by using set of power states that are defined for each device. These power states run from S1 through S6. The power states S3 and S4 are the two power states that control suspend and hibernate in Linux distributions like Ubuntu.

Suspend to help save your battery in Ubuntu Linux
The S3 state in Ubuntu is also called suspend. In Windows, this state is known as standby, while in OSX it is called sleep. The S3 state suspends processes, and saves all of the the operating system in memory. The memory portion of your computer is left on so that the information will remain in your system for the next time you 'wake' the computer up. In the S3 state, power is still being consumed by system memory. However, power consumption is at a considerably reduced rate. You can add days to your battery life between recharging when using suspend. Suspend is useful because it uses little power, and can turn you machine on quickly.

Hibernate to help save your battery in Ubuntu Linux
Hibernate, as the name implies, takes your computer into 'deeper' sleep. When ACPI enters S4 it will suspend off the processes, and write their memory to disk. There one advantage that hibernate has over suspend is that memory if written to an area of you computer that requires no power to remain in place. Even if you disconnect your power and battery, suspend mode will still be able to save all of your work in place. When re-connect your power and restart your machine from hibernate, your computer should come up as it was left.

It takes a little longer for the computer to come out of hibernate, than it does from suspend (sleep). This is because information needs to be read from disk, which takes a little longer than if read from memory. The advantage to hibernate is that that it requires virtually no battery power to save your information.

If you plan to install Ubuntu Linux on a laptop or netbook, be sure to check and see if hibernate and suspend work properly. Then you will be able maximize the efficiency of your battery.