In any computers installed with ‘Fixed’ ‘System’ hard disk(s), such ‘Fixed’ ‘System’ hard disk(s) from which the computer is started to run is/are so far not to be swapped or taken away and re-inserted while the computer is under the control of the operating system, which is running in the computer and specifically running on the ‘Fixed’ ‘System’ hard disk(s). Hot-Swap-Enabling’ device is especially designed with the capability for enabling ‘Hot-Swap’ (taken hereafter as meaning also ‘Hot-Plug’) for those ‘Non-Hot-Swappable’ hard disks attached to it. They are designed to have features meeting the following challenges for ‘Hot-Swapping’ as outlined in: http://www.maxtor.com/en/documentation/white_papers/sata_hot_plug_white_paper.pdf and quoted as follows: controlling electrostatic discharge during insertion of the HDD (Hard Disk Drive) into the system slot to avoid damaging the HDD; controlling in-rash current to the HDD from the host [i.e. the computer] to prevent voltage drops; ensuring the host is able to detect a newly inserted HDD; and properly establishing communications between the HDD and the host. Serial ATA (SATA) hard disk is designed with ‘Hot-Swap’ capability. However if it is used as the ‘System’ hard disk from which the computer first starts and draws its operating system, it is normally connected directly to the data and power cables separately leading out from the motherboard and the internal power supply of the computer and is still used as a ‘Fixed’ ‘System’ hard disk. It is not to be swapped when the operating system is running on it and using it as the ‘System’ hard disk. Used in this way, it should therefore be also covered under this invention. So ‘Hot-Swappable’ hard disk that is connectedly in one of the way of (a), (b) or (c) described and is used for storing and starting the system image of the operating system controlling the computer should also be covered under this invention. As other hard disks (other than Serial ATA hard disks or hard disks with similar technologies that are fixed internally and from which the computer system is started as defined above) mentioned above are not designed with ‘Hot-Swapping’ capability, they do not safely meet the above-mentioned challenges. These hard disks cannot therefore be ‘Hot-Swapped’ without being attached to device(s) especially designed to meet the above-mentioned challenges. Furthermore, if they are used as the ‘System’ hard disk(s) from which the computer draws the system image of its running operating system and runs the operating system on it, they are again ‘Non-Hot-Swappable’. So ‘Fixed’ ‘System’ hard disk is ‘Non-Hot-Swappable’ because either it has no Hot-Swappable’ capability or it is used as ‘System’ hard disk from which the computer starts drawing the system image of its running operating system and runs the operating system on it. Or both, it has no ‘Hot-Swappable’ capability and it is used as ‘System’ hard disk and attached as ‘Fixed’ ‘System’ hard disk as defined above. There is implementation for ‘Hot-Swapping’ such ‘Fixed’ ‘System’ hard disk, such as found at: http://www.sun.com/products-n-solutions/hardware/docs/html/816-2482-1 1/HDD_RM M_replace.html#91741
However it involves expensive ‘Hot-Swap-Enabling’ software and hardware and is only available by turning the operating system into a server-based operating system through mirroring the primary boot disk onto the server disk. And such method cannot be employed for standalone desktop computer or mobile notebook computer not connected to Local Area Network. Operating system for starting and controlling a computer has to come from a non-volatile mass storage medium. The above-mentioned ‘Fixed’ ‘System’ hard disks are usually used as such a primary non-volatile storage medium or storage device for storing the image of operating systems because they are relatively fast, reliable and cheap. Before the invention of running an operating system entirely in the volatile RAM (Random Access Memory) of a computer, every primary non-volatile storage medium or storage device in a standalone computer had to be fixed because the operating system controlling the computer had to start from and run on it. The advent and the possibility of running an operating system entirely in volatile RAM of a computer makes possible the use of external removeable USB disks or Magnetic-Optical disks or CDROM as the primary non-volatile storage medium so as to make the computer running disklessly. This development is illustrated by the invention, a PCT application, No. PCT/IBOO/00010, Title: Running Microsoft Windows 95/98 on Ramdisk, presented also by the author of the present invention. But these non-hard-disk storage media are relatively slow. At this moment, however most computers and their disk-based operating systems today are running on the above-mentioned ‘Fixed’ ‘System’ hard disk(s). And there has never been a revelation how these ‘Fixed’ ‘System’ hard disk(s) can be taken out safely for running a computer in a normal manner. Hard disk is a major source leading to computer failure. ‘Fixed’ ‘System’ hard disk is subject to daily wear and tear. The world-wide-web phenomenon and the habit of downloading files through internet makes computer virus infection a common headache of computer maintenance. Hard disk is the primary target of any virus attack. And yet, each disk-based computer is equipped with at least one such ‘Fixed’ ‘System’ hard disk. The advent of APM (Advanced Power Management) and ACPI (Advanced Configuration & Power Interface) and the developments in the sphere of Hot-Swapping technologies are intended to provide better power management and to increase flexibility and mobility of using a computer, including peripheral devices attached on or to it. Specifications for APM and ACPI can be found at: http://www.microsoft.com/whdc/archive/amp—12.mspx and http://www.acpi.info Now the use of hot-swappable hard disks or hard disks connected to device enabling ‘Hot-Swapping’ is very common for huge computer servers. Externally connected hot-swappable hard disks, such as MO disks, USB-IDE hard disks and Firewire-IDE hard disks also become in widespread use in personal computers and notebook computers. But one way or another, they are either comparatively costly or relatively slow and involves interface translation, which relies on proper driver support that is not always available.