| Time Machine | |
|---|---|
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 Time Machine screenshot |
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| Developer | Apple Inc. |
| OS | Mac OS X v10.5 |
| Genre | Backup software |
| License | Proprietary |
| Website | Time Machine |
Time Machine is a backup utility developed by Apple which is included with Mac OS X v10.5.
Contents |
Overview
Time Machine, like many backup utilities, creates incremental backups of files which can be restored at a later date.[1] It also supports limited restoration of files within applications that are specifically programmed to use Time Machine's functionality. Time Machine allows for machines to be backed to other Apple Macintosh Computers through Apple's AirPort networking, but does not support backing up to network attached storage drives.
User interface
Time Machine's user interface uses Apple's Core Animation API. Upon its launch, Time Machine "floats" the active Finder or application window from the user's desktop to a backdrop depicting a galaxy and star field. Behind the current active window are stacked windows, with each window representing a snapshot of how that folder or application looked on the given date and time in the past. When toggling through the previous snapshots, the stacked windows extend backwards, giving the impression of flying through a 'time tunnel'. While paging through these "windows from the past", a previous version of the data (or presently deleted data) may be retrieved.
Requirements
Time Machine requires a non-booting hard-drive or partition to be connected to the computer.[2] It can back up to internal hard-drives or partitions, but it is recommended that you back up to an external hard drive connected by USB or Firewire. According to Apple, it can only be backed up to network drives if they are being hosted by another computer running Leopard (including Leopard Server). However, a simple command in the Terminal application will allow you to use any network drive. Further, the volume needs to be formatted with the Mac OS extended file system, with journaling enabled.
Similar functionality in other operating systems
Microsoft's Windows Server 2003 and some versions of its Windows Vista operating system feature Shadow Copy (or a variation of it called previous versions in Vista), which creates snapshots of files and folders on a specific volume at a specific point in time that can later be retrieved. Both Time Machine and Shadow Copy use snapshots to achieve a similar useful purpose, however there is a major difference in the way in which Time Machine has been implemented. The main purpose of Windows Vista's previous versions feature and its Backup and Restore Center is to back up major operating system files and files from the user's home directory (Documents, Pictures, Downloads, etc). Further, Windows Previous Versions allows for retrieval of old data from snapshots taken with System Restore. And while Time Machine serves these functions, its interface allows for users to restore individual deleted photos from within iPhoto, and deleted items from within Mail, and the Address Book.
Unlike competing products, Time Machine only allows for limited network backup functionality. Backing up to other machines is limited to Apple Macintosh computers running Leopard; Time Machine will not backup to systems running Microsoft Windows or Linux. TimeVault is a GNOME-based application which will allow similar functionlity. A port to KDE is in the works.
Limitations
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This article or section may contain original research or unverified claims. Please improve the article by adding references. See the for details. (November 2007) |
Currently Time Machine has some limitations:
- Time Machine cannot create encrypted backups. However, home directories protected by FileVault are backed up in encrypted form upon logout.
- Time Machine cannot back up files stored on a partition which is not formatted with the HFS+ file system. Hence, it cannot back up Windows or Linux partitions.
- Time Machine cannot back up to network attached storage (NAS). The ability to back up to a drive attached to an Airport Express 802.11n base station was apparently dropped late in the development process.
- Time Machine does not support bootable backups. If the system becomes unbootable, a user must start up from their Mac OS X Leopard install DVD, then run Time Machine to restore their system. Reinstalling the operating system is not required.[3]
- Time Machine does not support the use of multiple backup disks. If a laptop user keeps multiple Time Machine disks (e.g, one at work and one at home) they must reconfigure Time Machine each time they switch disks.
- Due to Apple's continuation of the HFS+ file system, Time Machine does not support block-level backups. If even one entry in a large data file changes, the entire new version of the large file must be backed up. Other backup solutions will simply back up the portion of the file that has changed. This missing feature has raised serious concerns; the main reason is because Macintosh users sometimes make use of virtualization; virtual disk images are very large and change every time they are booted, making it essentially impractical to include these disk images in Time Machine backups. Another reason for the concern is because some developers continue to use single database files to store data --- a common example here would be Microsoft's Entourage, which stores all email messages in a single file.
See also
References
- ^ Apple. Apple - Mac OS X Leopard - Features - Time Machine. Retrieved on 2007-12-21.
- ^ Tom Krazit (August 7 2006). New Apple feature sends users back in time. CNet. Retrieved on 2006-08-07.
- ^ Apple (November 20 2007). Mac OS X 10.5 Help: Recovering your entire system. Apple. Retrieved on 2007-11-20.
External links
- Time Machine page at apple.com
- Time Machine video at apple.com
- Review of Time Machine and its technical background at arstechnica.com
- Activation of Network Disks in Apple Time Machine
