On Wed, Nov 2, 2016 at 9:01 PM, Jeff Kubina <jeff.kub...@gmail.com> wrote: > Thanks for the blog post, very interesting read. Some questions ... > > 1. Are the operations "Writes mutation to tablet servers’ WAL/Sync or flush > tablet servers’ WAL" and "Adds mutations to sorted in memory map of each > tablet." performed by threads in parallel?
Not for a batch from a client. Each batch of mutations from a client is processed by a single thread. Batches from separate clients can process in parallel. > > 2. Could the latency of hsync-ing the WALs be overcome by modifying Accumulo > to write them to a separate SSD-only HDFS? To maintain data locality it > would require two datanode processes (one for the HDDs and one for the SSD), > running on the same node, which is not hard to do. Christopher answered this. I just wanted to mention that I have run Accumulo on my laptop which has a SSD. Hsync is much faster there, like 10x faster. >
