Monthly Archives: October 2003

NBD – Distributed Data Storage on a LAN?

Re:NBD Does this (Score:5, Informative)
by dbarclay10 (70443) on Wednesday October 29, @04:37PM (#7341575)
(http://markybobdeb.sourceforge.net/)
Just to clarify what this guy is saying:

1) Make all your machines NBD servers. NBD for Linux [sourceforge.net”>, NBD for Windows [vanheusden.com”>. NBD stands for “network block device” and allows a client to use a server’s block device.
2) Set up a master client/server (using Linux or something else with a decent software RAID stack). This machine will be the only NBD *client*, and it will use all the NBD block devices exported by the rest of your network.
3) On the master set up in 2), create a Linux MD RAID array overtop all the NBD devices that are available.
4) Create a filesystem on the brand-spanking-new multi-machine RAID array.
5) Export it back to the other machines via Samba or NFS or AFS or what have you.

Why does only one machine (the “master server”) access the NBD devices, you ask? Because for a given block device, there can only be one client accessing it safely. Thus, if you want to make the RAID array available to anything other than the machine which is *running* the array off the NBD devices, you need to use something which allows concurrent access; something like NFS, Samba, or AFS.

Original /! thread:
http://ask.slashdot.org/askslashdot/03/10/29/205229.shtml?tid=126&tid=137&tid=198&tid=95