Running Windows from an external USB storage device began to be proposed in Redmond quite a long time ago. This article discusses why this technology has evolved, what is needed for it, and what scenarios it is intended for. Its use brings advantages especially in large companies, where computers may be without any central administration and the only thing that needs to be centrally managed are employees' flash drives.
If Windows boots from USB storage, nothing changes for the user. It can access the local drive. What can be disabled, however, is writing or reading from a USB partition that has Windows To Go on it. Such a partition can be marked as invisible and will appear offline in the system. USB storage with Windows To Go looks like an offline drive in disk manager.
The main advantage is more comfortable working from home. An employee can boot into the same environment on their home PC as at work. Another area of use is organizations where employees work on their own machines. There is no need to reconfigure the network or connect network drives. The employee simply boots Windows with company applications on his PC. Last but not least, this solution is advantageous when sharing one PC by multiple users. For example, a police officer boots the PC in his company car from his USB storage and takes the key back after the end of his shift. This will prevent sensitive data from being stored in the car.
Windows To Go will be able to be deployed on devices that have USB 2.0, 3.0 or eSATA. Windows recognizes specific machines according to SMBIOS UUID. The first time you boot from an unknown machine, the necessary drivers are installed. Windows 8 contains more drivers than previous Windows PCs, so on the vast majority of PCs it will not even be necessary to connect to Windows Update to download the necessary drivers.
The biggest challenge for developers was the problem of alternately booting Windows from different PC configurations. Therefore, USB storage is divided into two partitions. The first FAT32 partition of 300 MB containing boot managers for BIOS and UEFI. The second is the NTFS partition for the system and applications. It can be divided into two parts – one for the system, which is hidden, and the other for user data, which the user can write to. Currently, the smallest supported storage size is 32 GB.
An important new feature of the Windows 8 boot manager is the ability to boot from Windows To Go without this option being enabled in the BIOS. The user can go to the Control Panel and set there the option to boot from Windows To Go priority when present. This setting is accessible through system policies, so it can be set centrally. However, it is not a feature that will be retroactively implemented in Windows 7.
If the system is booted from storage outside the case, a problem logically arises – what happens if the user physically disconnects the storage while the system is running? In this case, the core freezes the system. If the storage is reconnected within one minute, the system will recover. Otherwise, the system will shut down.
Windows To Go leaves no trace on the computer it runs on. The paging file is located on a USB stick. BitLocker is supported. Windows Update works without changes.
Windows To Go offers new possibilities in the field of enterprise solutions. It’s useful, for example, if roaming profiles can't be deployed due to bandwidth requirements and storing app settings on SkyDrive is against company policy.
The article was written for TechNet Blog CZ/SK.