Disk storage

A drive is a unit of a computer to access ( read / write or read-only) on a storage medium for digital data. A distinction is made between a physical and a virtual drive. The physical, ie actually existing drives, can be divided into drives for removable media ( magnetic tape, diskette, CD, DVD, etc.) and hard drives. Virtual disks form a physical drive only after and can be used analogously.

Demarcation

While " drive" a mechanical device is implied in the word, there are also media with memory chips, no moving parts, is required for their access. These include memory cards, USB flash drives, device internal memory, etc. Although such devices are no drives in the strict sense, also they are so named because they have the same function from the user's perspective.

To summarize large volumes of data, proprietary systems are built that are only for data storage. These are connected via special protocols such as iSCSI with the application server via the network (NAS), or in a special storage area network (SAN ) connected for example with Fibre Channel. One speaks in such data storing disk subsystems, tape libraries and CD / DVD / WORM jukeboxes.

Drive letter

Microsoft operating systems represent the drives (more precisely, their partitions, which appear as the user as its own hard drive ) in capital letters. This was a property of CP / M and was adopted into the building upon operating systems DOS, Atari TOS, OS / 2, Microsoft Windows, and the operating system of the PlayStation. Traditionally called "A " and "B " floppy drives and "C: " the boot partition on the disk, and also "D:" the CD / DVD drive of your computer (if no other disks ( partitions ) are available)

Microsoft operating systems

The assignment of drive letter depends on MS- DOS -based systems, and due also in NT-based systems ( boot drive ) of the connection, the drives above ( ie, for example IDE channel and jumpers ), of the order of reloading the other driver and, where appropriate, the manual drive letter assignment in the control Panel.

Also CD and DVD drives and card readers are assigned their own drive letter (for card readers with multiple slots ( slots), each slot receives its own drive letter, as each slot is regarded as a separate drive). USB memory sticks are automatically inserted - assigned letters of their own - during operation. This is Windows 2000 and the case with drivers other seller starting from Windows 98

Just drive letter can be assigned for network access to another computer ( or network drive). Using the subst command line directories can own drive letter assigned. If more drives are available as letters, all letters will be awarded. For NT -based operating systems, then let drives engagement as similar to Unix in the filesystem using mount points.

It is also possible to set up virtual drives that do not pretend the computer existing physical drives. This technique is used for example when a CD is used frequently and the CD drive will not be damaged by continuous operation. For this, the image of the CD is stored on a physical disk and mounted as a virtual CD drive in the operating system.

And free areas of the main memory can be used as drives. These are referred to as RAM disks. There will lose the contents of the main memory when you restart or shut down the computer, ram disks can not be used as a mass storage. Their advantage lies in the much shorter access times and much higher data transfer rates.

UNIX - based operating system

Under Unix-like operating systems such as Linux or Mac OS X, received drives partly a device name that differs according to the type (SCSI, ATA ... ). On Linux, for example, usually are the first two characters of the type of drive, the third for the number; so called / dev / hda, the first ATA disk, / dev / sdb second SCSI disk or / dev/fd2 the third floppy drive. But there are also hierarchically oriented naming schemes that are based on the connection of these devices, or logical, in which only the type of the connected device is reflected.

These names are needed, for example, if a drive should be formatted. The normal access to drives in the current system is done but do not have device names, but via the location of the directory structure: these disks or partitions must there suspended from access to any point (mounted ) are. It is usual, for example, for CD -ROM drives / cdrom or / mnt / cdrom. After accessing this must be unmounted ( umount) again. This can also be done automatically by an automounter.

• Hardware