According jconsole on the main table I am having issues with: Capacity: 1164790 HitRate: .54 Size: 99753
Right now my KeysCachedFraction is 0.2. The current memory allocated is 3G. What's a suggested KeysCachedFraction value? Suhail On Sat, Jan 30, 2010 at 5:58 AM, Jonathan Ellis <jbel...@gmail.com> wrote: > the thing that will help most in 0.5 is to increase your > KeysCachedFraction to 0.2 or even more, depending on your workload. > > On Sat, Jan 30, 2010 at 5:23 AM, Suhail Doshi <digitalwarf...@gmail.com> > wrote: > > An issue I've been seeing is it's really hard to scale Cassandra with > reads. > > I've run top, vmstat, iostat. vmstat shows no swapping but iostat shows > > heavy saturation of %util and await times over 90ms with max rMB/s of > 7-8. > > > > I have over 7G of memory dedicated across two nodes. I am wondering what > the > > issue might be and how to solve this? I felt like 7 G would be enough. > > > > Suhail > > > > On Thu, Jan 28, 2010 at 7:32 PM, Ray Slakinski <r...@mahalo.com> wrote: > > > >> Cassandra auto shards, so you just need to point at your cluster and > >> cassandra does the rest. You should read up on different partitioners > though > >> before you go live in production, because its not too easy to switch > once > >> you make that decision. > >> > >> http://wiki.apache.org/cassandra/StorageConfiguration#Partitioner > >> > >> Ray Slakinski > >> On 2010-01-28, at 7:29 PM, Suhail Doshi wrote: > >> > >> > Another piece I am interested in is how cassandra distributes the data > >> > automatically. In MySQL you need to shard and you'd pick the shard to > >> > request info from--how does that translate in cassandra? > >> > > >> > On Thu, Jan 28, 2010 at 7:23 PM, Suhail Doshi <suh...@mixpanel.com> > >> wrote: > >> > > >> >> We've started to use Cassandra in production and just have one node > >> right > >> >> now. Here's one of our ColumnFamilys: > >> >> > >> >> 16G Jan 28 22:28 SomeIndex-5467-Index.db > >> >> 196M Jan 28 22:32 SomeIndex-5487-Index.db > >> >> > >> >> The first bottle neck you encounter is reads--writes are extremely > fast > >> even with one node. > >> >> > >> >> My question is, is the size of the *-Index.db files the amount of RAM > >> you need available for Cassandra to do reads fast? > >> >> > >> >> What are some configuration options you would need to tweak besides > the > >> JVM's max memory size being larger. Is there any default configurations > >> commonly missed? > >> >> > >> >> Next, if you provision more nodes will Cassandra distribute the data > in > >> memory so I don't need a single 16 GB node? Is there anything I need to > >> build in my application logic to make this work correctly. Ideally, if I > had > >> a 16 GB index, I'd want it spread across 4 4GB nodes. Can any client > connect > >> to any one node request info and it will get the info back from a node > that > >> has that part of the index in memory? > >> >> > >> >> What's the best way to do efficient reads? > >> >> > >> >> Suhail > >> >> > >> >> > >> > >> > > > > > > -- > > http://mixpanel.com > > Blog: http://blog.mixpanel.com > > > -- http://mixpanel.com Blog: http://blog.mixpanel.com
