I have never use recovery hd before (hold down option key method) and have few questions regarding about this recovery hd after updated to Mavericks 10.9 and have also created a new recovery hd for mavericks 10.9 1. Recovery HD： 容量： 650 MB（650,002,432 字节） BSD 名称： disk0s3 内容： Apple_Boot this disk0s3 size looks like unchanged compared to 10.8, however if I go to os x TOOLS from recovery hd(hold options key at start), the disk size shows 1.25 GB? why is that? and also Mavericks size is over 5gb, if i use the recovery, do i need to download anything since the recovery hd is only 1.25GB. 2. if i use the recovery hd to recovery the system, do i have to backup the applications?