what happens to performance when a node crashes
I've worked with another MPP product which pairs nodes to achieve fault tolerance against losing a node due to h/w faults etc. This means that in say a 12 node system, if 1 node fails, the 2nd node in the pair has to do the job of both nodes, so the overall system throughput falls to that of a 6 node system (well nearly) ... ie the other pairs finish their work and then have to wait for the single node to complete. This can be partly tackled by grouping nodes into 4s rather than pairs, but this then introduces diskspace drawbacks.
Apologies if Ive missed this in the documentation, but can someone explain what happens to Vertica performance if a node drops out (assuming the system is still ksafe). Do querys access just the main projection (with the buddy projection maintained purely as a backup), or (where K=1) can they access both the main and buddy projection in parallel ... meaning that if one node goes down, performance would drop because only one projection is available (just like the other MPP Ive worked with) ?