Rob, Thanks for the reply. I do have vnodes. I was not aware of the -par flag on the repair command, I was actually referring to have repair run on both nodes A & B at the same time. It sounds like though, that I should probably be using this -par flag but to do it per node sequentially one after the other?
Right now just running 'nodetool repair' on one node is taking ~3.5 days, with 24 nodes I am now starting to question whether or not I should be increasing gc_grace_second to be much longer than the default 10 days since it's going to take longer than 10 days to repair the whole cluster. Thanks, Stan On Fri, Aug 14, 2015 at 2:44 PM, Robert Coli <rc...@eventbrite.com> wrote: > On Fri, Aug 14, 2015 at 11:33 AM, Stan Lemon <sle...@salesforce.com> > wrote: > >> Is it safe to run repairs in parallel on multiple nodes in the same DC at >> the time or is this discouraged? >> > > If you have enough headroom, it's safe. It may impact latency. > > It also depends on whether you have vnodes or not. If you don't, and you > use -par option to repair, you will repair a set of nodes but not all > nodes. If you do use vnodes, you will effectively repair a range already on > all nodes with -par repair. If you do a rolling -par -pr on a cluster with > vnodes, you'll probably be getting close to ideal parallelism anyway. > > =Rob > >
