Re: reads/writes performance

Can you send the mongod logs and mongostat output from a period where
there are queues?

On Wed, Nov 30, 2011 at 2:51 PM, Cristian <gcristian@...> wrote:
> Dont understand why, in a replica set scenario, i have my read
> operations getting queued (rq: in waves, from 200 to 1000 each 10
> seconds) on my read-only secondaries, waiting for write locks sent to
> the primary I guess. I'm using replica sets as an attempt to scale on
> reads without being affected by write locks running on the primary
> node, am i right?
>
> I'm using the Java driver, declaring the 3 instances (as
> ServerAddress[]) for him to balance between read/write operations from
> my webapp nodes, with the slaveOk on. (going to ReadPreference usage
> from latest release)
>
> I have 500 reads/sec now, 50 inserts/sec, 200 updates/sec, and a ratio
> of 10/1 reads/write, (both to single docs),
> Database allocated: 20 Gb DB with 5M docs (expecting to reach up to
> 400M docs in a month and stop growing) good free memory, and mongod
> processes highly idle. Need to go to 1/1 ratio....  My mongod
> globalLock ratio is: 0.1, my index miss is very slow (less than 100),
> index size is small, 600 Mb. The 3 mongod servers are in EC2 large
> nodes, version 2.0.1
>
> For this numbers it's expected to see reads enqueued causing latency
> growth ? smoothly, but fatal to my webapp reads...
>
> What about changing my current mongo's read() & update() separated
> operatios, to findAndModify() with returnNew=false ?, should I gain in