wok-current diff nbd/description.txt @ rev 24992

Up sip (4.19.25)
author Pascal Bellard <pascal.bellard@slitaz.org>
date Sat May 14 18:19:29 2022 +0000 (2022-05-14)
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     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/nbd/description.txt	Sat May 14 18:19:29 2022 +0000
     1.3 @@ -0,0 +1,21 @@
     1.4 +With this compiled into your kernel, Linux can use a remote server
     1.5 +as one of its block devices.
     1.6 +Every time the client computer wants to read /dev/nbd0, it will send
     1.7 +a request to the server via TCP, which will reply with the data
     1.8 +requested.
     1.9 +This can be used for stations with low disk space (or even diskless
    1.10 +- if you use an initrd) to borrow disk space from other computers.
    1.11 +Unlike NFS, it is possible to put any file system on it.
    1.12 +But (also unlike NFS), if someone has mounted NBD read and write,
    1.13 +you must assure that no one else will have it mounted.
    1.14 +
    1.15 +Current state:
    1.16 +It currently works. Network block device is pretty stable.
    1.17 +It was originaly thought that it is impossible to swap over TCP;
    1.18 +this turned out not to be true.
    1.19 +However, to avoid deadlocks, you will need at least Linux 3.6.
    1.20 +
    1.21 +It is possible to use NBD as the block device counterpart of FUSE,
    1.22 +to implement the block device's reads and writes in user space.
    1.23 +To make this easer, recent versions of NBD (3.10 and above)
    1.24 +implement NBD over a Unix Domain Socket, too.