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RAM drives use normal system memory as if it were a partition on a physical hard drive rather than accessing the data bus normally used for secondary storage. Though RAM drives can often be supported directly in the operating system via special mechanisms in the OS kernel, it is generally simpler to access a RAM drive through a virtual device ...
This driver provides support for four kinds of memory backed virtual disks: malloc, preload, vnode, swap. Disks may be created with the next command line tools: mdconfig and mdmfs. An example of how to use these programs follows. [3] To create and mount memory disk with mdmfs: # mdmfs -F newimage -s 5m md0 /mnt
To implement memory ballooning, the virtual machine's kernel implements a "balloon driver" that allocates unused memory within the VM's address space into a pool of memory (the "balloon"), which makes that memory unavailable to other processes on that VM.
Virtual memory combines active RAM and inactive memory on DASD [a] to form a large range of contiguous addresses.. In computing, virtual memory, or virtual storage, [b] is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" [3] which "creates the illusion to users of a very large (main) memory".
Virtual memory systems abstract between physical RAM and virtual addresses, assigning virtual memory addresses both to physical RAM and to disk-based storage, expanding addressable memory, but at the cost of speed. NUMA and SMP architectures optimize memory allocation within multi-processor systems. While these technologies dynamically manage ...
A modern computer operating system usually uses virtual memory to provide separate address spaces or separate regions of a single address space, called user space and kernel space. [1] [a] Primarily, this separation serves to provide memory protection and hardware protection from malicious or errant software behaviour.
The virtual device driver can also send simulated processor-level events like interrupts into the virtual machine. Virtual devices may also operate in a non-virtualized environment. For example, a virtual network adapter is used with a virtual private network, while a virtual disk device is used with iSCSI.
Virtual addressing allows the kernel to make a given physical address appear to be another address, the virtual address. Virtual address spaces may be different for different processes; the memory that one process accesses at a particular (virtual) address may be different memory from what another process accesses at the same address.