[Paul and I both read the list; no need to add Cc] On Sat, Feb 11, 2012 at 12:50:19AM +0800, harryxiyou wrote: > Hi Wouter, > > I have some questions to ask you, which are like following. > > 1, Pavel said "Unlike NFS, it is possible to put any file system on it. But > (also unlike NFS), if someone has mounted NBD read/write, you must > assure that no one else will have it mounted. " on his own page. The > URL is http://atrey.karlin.mff.cuni.cz/~pavel/nbd/nbd.html . But i can not > understand '' if someone has mounted NBD read/write, you must > assure that no one else will have it mounted.". What is exact meaning of > this sentence. > One of my thoughts looks like this. We have two users, a1 > and a2 , who > have logined into a Linux OS. If a1 mounted NBD read/write, a2 must not > mount it currently, right?
Yeah, pretty much. > 2, I have seen the main function of nbd-server.c, which version is nbd-2.9.15. > Some stuffs confuse me like following. > 1> 1882 line: memset(pidftemplate, '\0', 256); > I just see pidftemplate is used in the daemon function. > But i am not > sure what the pid file is used for. So we can easily kill the server afterwards, if needs be. > And also i don't know the meaning of this daemon function in nbd-server.c. detach from stdin and stdout, and start serving as a background daemon. > 2> 1873: SERVER *server; > If we have (server != NULL && (0 == server->port)) we will > execute inetd > mode. I have searched the characters of inetd but i am not sure what > the > meanings of inetd in our nbd-server.c do. And in what > situations, we will do > the inetd mode, which should do what jobs? inetd is an "internet superdaemon", used to run services without having to have a separate process running for each and every service (at least, as long as no client is using the service). > 3> 1928: dousers(); > I just tracked this function. It looks like it will set the > running group and user informations. Correct. > Why should we do this? Because some people think it's a bad idea to run a service as root. > Is it related to what > pavel said > "if someone has mounted NBD read/write, you must assure that no one > else > will have it mounted". Right ? No. -- The volume of a pizza of thickness a and radius z can be described by the following formula: pi zz a ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Nbd-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/nbd-general
