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Linux Journal: The Network Block Device

Apr 30, 2000, 01:29 (0 Talkback[s])
(Other stories by P. T. Breuer)

"A network block device (NBD) driver makes a remote resource look like a local device in Linux, allowing a cheap and safe real-time mirror to be constructed."

"The Network Block Device driver offers an access model that will become more common in this network-oriented world. It simulates a block device, such as a hard disk or hard-disk partition, on the local client, but connects across the network to a remote server that provides the real physical backing. Locally, the device looks like a disk partition, but it is a façcade for the remote. The remote server is a lightweight piece of daemon code providing the real access to the remote device and does not need to be running under Linux. The local operating system will be Linux and must support the Linux kernel NBD driver and a local client daemon. NBD setups are being used by us to provide real-time off-site storage and backup, but can be used to transport physical devices virtually anywhere in the world."

"The NBD has some of the classic characteristics of a UNIX system component: it is simple, compact and versatile. File systems can be mounted on an NBD... NBDs can be used as components in software RAID arrays... and so on. Mounting a native Linux EXT2 file system over an NBD gives faster transfer rates than mounting an NFS (Network File System) from the same remote machine"

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