Haven't seen much success between 0.1, 0.2, 0.3 On Sat, Jan 30, 2010 at 4:04 PM, Jonathan Ellis <jbel...@gmail.com> wrote:
> you want to get hitrate to 0.9 or so, i.e. 90% of index lookups don't > have to hit disk. play with KCF and see what happens. and use > jconsole to see how close you are getting to your 3GB limit (hit the > GC button to see how much memory is "really" being used, and then add > 25% or so for a reasonable padding). > > On Sat, Jan 30, 2010 at 5:46 PM, Suhail Doshi <digitalwarf...@gmail.com> > wrote: > > 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 > > > -- http://mixpanel.com Blog: http://blog.mixpanel.com
