RAM drive

A RAM disk (also Ramdrive ) is a virtual and temporary disk in memory (RAM ) of a computer. It is mainly used when other physical storage media to slow or while the computer is re-installed, are not available.

When you create a certain amount of memory is statically or dynamically for the RAM disk reserved ( " diversion " ), while addressed as a hard disk or generally as an extra drive, formatted with a file system and finally hung up.

Benefits

In contrast to the direct addressing of memory by a computer program the programmers are by using a RAM disk associated with the file management operating system services are available. For the user, there is the advantage that can work both on disk and in memory with a RAM disk computer programs without modifications with data. The advantage of a RAM disk in comparison to the hard disk is the saving of disk accesses and the associated significantly higher write and access speed, which explains the use in supercomputers, and the reduction of wear. For example, ensure that the time required for starting is reduced during the boot process of a computer frequently used commands stored in memory. As for access to the main memory, less energy is needed is for mobile computing also the energy-saving effect and the associated prolonged battery life of advantage. Similar to the example given for the starting operation is accessed with the appropriate configuration to frequently used files in memory, so that the internal hard drive can be put into sleep mode more often or longer - which improves the battery runtime increases again.

Disadvantages

Disadvantages of the RAM disk are that the space in question the free memory, so the operating system and other programs for caching no longer available. After the system is restarted ( eg after a crash), the contents of the RAM disk in general is gone (except for reset-fast RAM disks ). Since memory is one of the volatile storage media, disappears if the power supply (eg when switching off ) with the memory content and the ramdisk content. Therefore, no important data should be stored on the RAM disk, unless the uninterruptible power supply of the computer is guaranteed. Furthermore, should be backed up any files still required before shutting down the computer (eg, automated via script ). In terms of price per memory size matters this way to the more expensive storage method.

Dissemination

All major operating systems provide drivers to create a RAM disk (notably most Ramdrive ). Nevertheless, there are numerous gleichzweckige software third-party offerings, which are supplemented by useful functions. Thus, the content of the RAM disk, for example at shutdown or at one minute intervals on disk are backed up. Even more flexible RAM disk parameters can be set here, depending on the version.

The operating system of the Amiga Commodore there are two different RAM disks in the operating system. The one used at the start of a definable amount of memory, while the other dynamic memory requests or releases and thus adapts to the memory requirements. The former has the advantage that its contents a computer restart (warm start) survived as long as the storage area was not overwritten by an uncontrolled crashing computer program.

On Unix operating systems, the RAM disk can be used by the / dev / shm ( shm for shared memory, shared memory).