What happens when suspended?

Question

I have a laptop - Lenovo T60.

When I close the lid, I see that the machine goes into suspended mode. The moment I open the lid, the laptop is instantly a live.

My concern - Does going into suspended mode make it safe to trasnport the computer - eg: travel on a bumpy road.

I ask because I'm not sure which parts shut off... For example, if the hard drive is still running, I'd say it's never safe to travel with the laptop in this mode.

I'd like some thoughts on this. Thanks!

Answer 1

Suspend writes the info to RAM (memory) & still uses power: drive(s), cpu and the moniter(s) are powered off.
The RAM modules are placed in self refresh mode and the CPU is powered off. The chipset is responsible for using the standby power to stay on enough to reactivate the main power supply when a button is pressed

and if you want to know what hibernate is:

Hibernate writes info to hard drive then powers laptop off.
Hibernate is resumed by pressing the power button.

So in terms of optimising battery life hibernate is better, but can take as much time as powering off, suspend is quicker but still uses power.

And in your question concerning hdd life. You should be able to drive over bumpy roads because the disk drive stops spinning.

Answer 2

pm-suspend

During suspend most devices are shutdown, and system state is saved in RAM. The system still requires power in this state. Most modern systems require 3 to 5 seconds to enter and leave suspend, and most laptops can stay in suspend mode for 1 to 3 days before exhausting their battery.

pm-hibernate

During hibernate the system is fully powered off, and system state is saved to disk. The system does not require power, and can stay in hibernate mode indefinitely. Most modern systems require 15 to 45 seconds to enter and leave hibernate, and entering and leaving hibernate takes longer when you have more memory.

pm-suspend-hybrid

Hybrid-suspend is the process where the system does everything it needs to hibernate, but suspends instead of shutting down. This means that your computer can wake up quicker than for normal hibernation if you do not run out of power, and you can resume even if you run out of power. s2both(8) is an hybrid-suspend implementation.

Answer 3

Moveable parts?

If any moveable parts are running, the Laptop, especially Lenovo and HDD vendors such as WesternDigital should be smart enough to design their laptops to handle such stress, e.g. covered fan.

Status

You can determine accoustically, or by commands, whether moveable parts are running.

Check whether HDD is active/idle or standby (not spinning):

$ sudo hdparm -C /dev/sda

/dev/sda is usually the primary HDD. You can determine your device names by using the lsblk command, which stands for “list block devices”.

Check the fan rotation speed:

$ sensors

As far as I know, there is no SCSi multimedia command in the command set, which allows directly reading the optical drive rotation speed, but optical drives should usually be far less fragile than hard drives, and if anything breaks, then it is the drive, not the disc. But you can reduce the rotation speed: $ eject -x 20

If you would like to know more about each command, then you can use the --help command switch or man command, maybe help depending on some distributions.

Hard drives are designed to handle some stress and minimize damage:

• Writing head airflow control - avoid headcrash.
• If freefall or too strong shakes are detected by sensors inside the HDD, it will quickly spin down and move head to safe position to minimize physical damage.
• If the air pressure is too low (i.e. usually at high altitudes), which can cause the airflow to break like on aircraft stalling, the drive's internal protection mechanisms are accordingly more paranoid, and may even suspend operation temporarily.
• HDDs are usually mounted upside down in laptops since decades.