Thanks for your responses.
On Mon, Mar 1, 2010 at 2:48 AM, Terrence Martin <[email protected]> wrote: > Mag Gam wrote: >> >> I just setup my first hadoop cluster with 5 nodes. What is the best >> way to check if replication is really working? I assume the best way >> is to power down 2 nodes and see if I can still reach my data? >> >> Or are there any others ways? >> >> TIA >> > > Well if you run > > hadoop fsck / > > it will give you a report of the number of replicas, if a file has less than > your configured replicas it will tell you that you are under replicated. > > As for powering off 2 nodes, well that will likely result in a few missing > blocks unless you have more than 2 replicas of each block. Now if you turn > off one data node after a while Hadoop will replicate the blocks to the > remaining 4 nodes, when you turn the 5th back on you will have over > replicated blocks. > > Terrence > >
