summaryrefslogtreecommitdiff
path: root/Documentation/blockdev/nbd.txt
diff options
context:
space:
mode:
authorSrikant Patnaik2015-01-11 12:28:04 +0530
committerSrikant Patnaik2015-01-11 12:28:04 +0530
commit871480933a1c28f8a9fed4c4d34d06c439a7a422 (patch)
tree8718f573808810c2a1e8cb8fb6ac469093ca2784 /Documentation/blockdev/nbd.txt
parent9d40ac5867b9aefe0722bc1f110b965ff294d30d (diff)
downloadFOSSEE-netbook-kernel-source-871480933a1c28f8a9fed4c4d34d06c439a7a422.tar.gz
FOSSEE-netbook-kernel-source-871480933a1c28f8a9fed4c4d34d06c439a7a422.tar.bz2
FOSSEE-netbook-kernel-source-871480933a1c28f8a9fed4c4d34d06c439a7a422.zip
Moved, renamed, and deleted files
The original directory structure was scattered and unorganized. Changes are basically to make it look like kernel structure.
Diffstat (limited to 'Documentation/blockdev/nbd.txt')
-rw-r--r--Documentation/blockdev/nbd.txt47
1 files changed, 47 insertions, 0 deletions
diff --git a/Documentation/blockdev/nbd.txt b/Documentation/blockdev/nbd.txt
new file mode 100644
index 00000000..aeb93ffe
--- /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.