Is root disk the same thing as boot disk?

[Zhuyi Xue]

They have different names, but look the same conceptually. Are they?

Each instance has an associated root persistent disk on which the instance's root file system is stored. from https://cloud.google.com/compute/docs/disks/persistent-disks

--boot-disk-size BOOT_DISK_SIZE from `gcloud compute instances create --help`

[George]

Hello Zhuyi,

As you mentioned, the root persistent disk has the root file system and the boot sectors which makes the instance boot successfully. As both root file system and boot sectors are present it makes the disk a root persistent disk and a boot disk. Another way to see the --boot-disk-size is to be able to differentiate between the main attached disk (root persistent disk) and a secondary disk attached to the instance.

I hope this helps.

Sincerely,

George

[Zhuyi Xue]

Very clear. Thank you!