In last article (The Method for Mac PC to Back Up and Recover Data-Part 1) we have introduced some parts of Mac OS X, in this article we will bring more to you. Let’s check it out.
1. NetInstall
NetInstall is remote installation tool which requires the supporting from Mac OS X Server. The purpose of Netlnstall is installing but not backing up. But the steps to achieve NetInstall include doing a network boot disk image. The images need to use a special version of OS X server software to create image with dmg file is different, because it contains web content.
2. Unix and Apple systems commands.
In addition to the above software, Mac OS X system Lidai some Unix or Apple’s own system commands, such as: cp, ditto, rsync, asr, even the image of the function hdiutil. However, these commands have their applicable conditions, not all commands are available to a file or folder was copied to all properties. And for most users, I do not know how it is for the command to start.
Speaking from the perspective of recovery from Mac OS 10.1 to Mac OS 10.4, Apple does not provide more convenience to the user. Finder only one undo, the results, once the user to the file or folder by mistake pulled trash, not timely undo, then it can not be reset. (Of course, third-party software, or can help). If the system is wrong, there is a recovery under Windows (Recovery) feature that allows the user to start again, the system automatically detect and recover. Under Windows you can also allow users to choose the last successful login information to log on, and these do not have a Mac.
So, Time Machine, as a backup tool, on the one hand to make up for the lack of Mac OS X version before, on the one hand have a new technology to solve other systems or backup software can not solve the problem, plus its cool user interface and well-known gimmicks on stage.
Apple Time Machine’s mechanism of action is this:
After the first time users start Time Machine, the software will do the entire disk cloning. After every hour, Time Machine on the right FSEvents Mac OS X system (file system events) systems to communicate and see what happens. FSEvents process all changes to the system for continuous tracking. When they find the system changes over the last one hour later, Time Machine to back up those files change. After the first day of every hour will be cleared automatically backup, weekly backups every day of the week will be automatically removed. So it saves a backup space while maintaining a complete system backup.
Time Machine according FSEvents provide information on the changes made to the file backup, incremental backup itself belongs (incremental backup), also create a rigid link (Hard Link) of the file has not changed. From the point of view of the file system, the file on the disk, but is a bunch of data, files, directories by rigid link this data with the file directory linked. If you delete the hard links, users can not find the file, although this time may well file exists on disk. In Mac OS X under the Finder’s Empty Trash (Empty Trash) function to delete the file is actually a hard link to the file is deleted. If you use recovery software is so “deleted” file is covered as long as no new files on the disk, may still be looking back.
Under normal file system and disk format, a file has only one hard link. Apple for this new feature to the disk format has been modified to allow a number of hard links to a file. Rigid link is actually a pointer, the pointer is stored in the backup files than backup save both time and space. Moreover, due to the presence of these pointers, through the user interface, you can recall a time in the system to all files.
I do hope you enjoy this article and learn the things you need in it, see you at the part 3 next time.