Depending on the key, the request would have been proxied to the first or second node. The CLI uses a consistency level of "ONE", meaning that only a single node's data would have been considered when you get(). Also, the responsible nodes for a given key are mapped accordingly at request time, and proxy requests are made internally on your behalf. This allows the R+W>N to hold, where N is the replication factor. It closes the subset of active nodes responsible for a key in a deterministic way.
See http://www.slideshare.net/benjaminblack/introduction-to-cassandra-replication-and-consistency for more information. On Tue, Jun 1, 2010 at 1:43 AM, David Boxenhorn <da...@lookin2.com> wrote: > I don't think it can be the case that "at most data in the token range > assigned to that node will be affected" - the new node had no knowledge of > any of our data. Any fake "data" that it might have had through some error > on my part could not have been within the range of real data. I had 4.25 G > of data on the 1st server, and as far as I could tell I couldn't access any > of it. > > > On Tue, Jun 1, 2010 at 9:10 AM, Jonathan Ellis <jbel...@gmail.com> wrote: >> >> To elaborate: >> >> If you manage to screw things up to where it thinks a node has data, >> but it does not (adding a node without bootstrap would do this, for >> instance, which is probably what you did), at most data in the token >> range assigned to that node will be affected. >> >> On Tue, Jun 1, 2010 at 12:45 AM, David Boxenhorn <da...@lookin2.com> >> wrote: >> > You say "no", but that is exactly what I just observed. Can I have some >> > more >> > explanation? >> > >> > To recap: I added a server to my cluster. It had some junk in the >> > system/LocationInfo files from previous, unsuccessful attempts to add >> > the >> > server to the cluster. (They were unsuccessful because I hadn't opened >> > the >> > port on that computer.) When I finally succeeded in adding the 2nd >> > server, >> > the 1st server started returning null when I tried to get data using the >> > CLI. I stopped the 2nd server, deleted the files in system, restarted, >> > and >> > everything worked. >> > >> > I'm afraid that this, or some similar scenario will do the same, after I >> > go >> > live. How can I protect myself? >> > >> > On Mon, May 31, 2010 at 10:10 PM, Jonathan Ellis <jbel...@gmail.com> >> > wrote: >> >> >> >> No. >> >> >> >> On Mon, May 31, 2010 at 10:47 AM, David Boxenhorn <da...@lookin2.com> >> >> wrote: >> >> > So.... this means that I can take my entire cluster off line if I >> >> > make a >> >> > mistake adding a new server??? Yikes! >> >> > >> >> > On Mon, May 31, 2010 at 6:41 PM, David Boxenhorn <da...@lookin2.com> >> >> > wrote: >> >> >> >> >> >> OK. Got it working. >> >> >> >> >> >> I had some data in the 2nd server from previous failed attempts at >> >> >> hooking >> >> >> up to the cluster. When I deleted that data and tried again, it said >> >> >> "bootstrapping" and my 1st server started working again. >> >> >> >> >> >> On Mon, May 31, 2010 at 4:50 PM, David Boxenhorn <da...@lookin2.com> >> >> >> wrote: >> >> >>> >> >> >>> I am trying to get a cluster up and working for the first time. >> >> >>> >> >> >>> I got one server up and running, with lots of data on it, which I >> >> >>> can >> >> >>> see >> >> >>> with the CLI. >> >> >>> >> >> >>> I added my 2nd server, they seem to recognize each other. >> >> >>> >> >> >>> Now I can't see my data with the CLI. I do a get and it returns >> >> >>> null. >> >> >>> The >> >> >>> data files seem to be intact. >> >> >>> >> >> >>> What happened??? How can I fix it? >> >> >>> >> >> >> >> >> > >> >> > >> >> >> >> >> >> >> >> -- >> >> Jonathan Ellis >> >> Project Chair, Apache Cassandra >> >> co-founder of Riptano, the source for professional Cassandra support >> >> http://riptano.com >> > >> > >> >> >> >> -- >> Jonathan Ellis >> Project Chair, Apache Cassandra >> co-founder of Riptano, the source for professional Cassandra support >> http://riptano.com > >
