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| author | merge <null@invalid> | 2009-01-22 13:55:32 +0000 |
|---|---|---|
| committer | Andy Green <agreen@octopus.localdomain> | 2009-01-22 13:55:32 +0000 |
| commit | aa6f5ffbdba45aa8e19e5048648fc6c7b25376d3 (patch) | |
| tree | fbb786d0ac6f8a774fd834e9ce951197e60fbffa /Documentation/blockdev/nbd.txt | |
| parent | f2d78193eae5dccd3d588d2c8ea0866efc368332 (diff) | |
MERGE-via-pending-tracking-hist-MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141
pending-tracking-hist top was MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141 / fdf777a63bcb59e0dfd78bfe2c6242e01f6d4eb9 ... parent commitmessage:
From: merge <null@invalid>
MERGE-via-stable-tracking-hist-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040
stable-tracking-hist top was MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040 / 90463bfd2d5a3c8b52f6e6d71024a00e052b0ced ... parent commitmessage:
From: merge <null@invalid>
MERGE-via-mokopatches-tracking-hist-fix-stray-endmenu-patch
mokopatches-tracking-hist top was fix-stray-endmenu-patch / 3630e0be570de8057e7f8d2fe501ed353cdf34e6 ... parent commitmessage:
From: Andy Green <andy@openmoko.com>
fix-stray-endmenu.patch
Signed-off-by: Andy Green <andy@openmoko.com>
Diffstat (limited to 'Documentation/blockdev/nbd.txt')
| -rw-r--r-- | Documentation/blockdev/nbd.txt | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/Documentation/blockdev/nbd.txt b/Documentation/blockdev/nbd.txt new file mode 100644 index 00000000000..aeb93ffe641 --- /dev/null +++ b/Documentation/blockdev/nbd.txt @@ -0,0 +1,47 @@ + Network Block Device (TCP version) + + What is it: With this compiled in the kernel (or as a module), Linux + can use a remote server as one of its block devices. So every time + the client computer wants to read, e.g., /dev/nb0, it sends a + request over TCP to the server, which will reply with the data read. + This can be used for stations with low disk space (or even diskless - + if you boot from floppy) to borrow disk space from another computer. + Unlike NFS, it is possible to put any filesystem on it, etc. It should + even be possible to use NBD as a root filesystem (I've never tried), + but it requires a user-level program to be in the initrd to start. + It also allows you to run block-device in user land (making server + and client physically the same computer, communicating using loopback). + + Current state: It currently works. Network block device is stable. + I originally thought that it was impossible to swap over TCP. It + turned out not to be true - swapping over TCP now works and seems + to be deadlock-free, but it requires heavy patches into Linux's + network layer. + + For more information, or to download the nbd-client and nbd-server + tools, go to http://nbd.sf.net/. + + Howto: To setup nbd, you can simply do the following: + + First, serve a device or file from a remote server: + + nbd-server <port-number> <device-or-file-to-serve-to-client> + + e.g., + root@server1 # nbd-server 1234 /dev/sdb1 + + (serves sdb1 partition on TCP port 1234) + + Then, on the local (client) system: + + nbd-client <server-name-or-IP> <server-port-number> /dev/nb[0-n] + + e.g., + root@client1 # nbd-client server1 1234 /dev/nb0 + + (creates the nb0 device on client1) + + The nbd kernel module need only be installed on the client + system, as the nbd-server is completely in userspace. In fact, + the nbd-server has been successfully ported to other operating + systems, including Windows. |