I am using normal SATA disk, actually I was worrying about whether it is okay if every time cassandra using all the io resources? further more when is the good time to add more nodes when I was just using normal SATA disk and with 100r/s it could reach 100 %util....
how large the data size it should be on each node? below is my iostat -x 2 when doing node repair, I have to repair column family separately otherwise the load will be more crazy: Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sda 1.50 1.50 121.50 14.00 3.68 0.30 60.19 116.98 1569.46 59.49 14673.86 7.38 100.00 On Sun, Jul 24, 2011 at 8:04 AM, Jonathan Ellis <jbel...@gmail.com> wrote: > On Sat, Jul 23, 2011 at 4:16 PM, Francois Richard <frich...@xobni.com> wrote: >> My understanding is that during compaction cassandra does a lot of non >> sequential readsa then dumps the results with a big sequential write. > > Compaction reads and writes are both sequential, and 0.8 allows > setting a MB/s to cap compaction at. > > As to the original question "do I need to add more machines" I'd say > that depends more on whether your application's SLA is met, than what > % io util spikes to. > > -- > Jonathan Ellis > Project Chair, Apache Cassandra > co-founder of DataStax, the source for professional Cassandra support > http://www.datastax.com >
