Question: Is it safe to disconnect a SATA disk during sleep Windows 7? Is the disk powered off when the computer successfully have entered sleep mode? This is not my system disk, it’s just a spinning disk for my photos.
Answer: Sleep mode in Windows saves your machines current state to memory and powers down your hard drive and monitor.
In case of external drives specially those that are connected through usb and are detected as external, Since you are using windows , the OS is smart enough to recognize that the external devices can be removed at any time and disables the write cache. This reduces the chances of data corruption. ?
So you can safely assume that you can remove your external drives without any data corruption. However as Ramhound pointed out – your system might crash if you remove your primary disk. ?
Systems have multiple power states from S-0 to S-4 and G-4.S-0 is active work state and G-4 is full power down, where machine would need to reboot to power up. ?
S-1 to S-3 are successive states of Sleep and S-4 is hibernate ?state.When the machine reaches state S-1 the processor shuts down.At S-2 It loses hardware context and loses contents of cache ( this should also include all writing caches ). This should further protect you against any data corruption.At S-3 (your default sleep mode) some more chips on the motherboard might be switched off. ?
So long story short, removing the hard drive while the machine is in sleep mode should not affect the health of the hardware as there are multiple checks built in to protect you against it. ?
Update marked S-3 as the default sleep mode – resource