2011/12/8 Piotr Kołaczkowski <pkola...@ii.pw.edu.pl>: > Right, this would be the best option to have an ability to write into > multiple log files, put on multiple disks. I'm not sure if it is part of > that ticket, though.
It's not. I don't think anyone needs more than 80MB/s or so of commitlog bandwidth for a while. > BTW: I'm not so sure if multiple, parallel writes to a memory mapped file > would be actually slower or faster than sequential writes. I think the OS > would optimise the writes so that physically they would be sequential, or > even delay them until fsync (or low cached disk buffers), so no performance > loss would occur Right. What we're trying to fix here is having a single thread doing the copying + checksumming being a bottleneck. The i/o pattern should stay more or less the same. -- Jonathan Ellis Project Chair, Apache Cassandra co-founder of DataStax, the source for professional Cassandra support http://www.datastax.com
