Re: Cassandra London UG meetup Monday
We could probably skype you in! Or maybe via ustream or something. Contact me offline at dave.gard...@imagini.net and we can work something out. Dave On Saturday, 19 March 2011, Ashlee Saunders wrote: > Hello Dave, > I am in Australia and was wondering if this group could do a phone hookup? > Ash > > On 19/03/2011, at 2:25 AM, Dave Gardner wrote: > > Hi all, > > Anyone based in the UK may be interested in our user group meetup on Monday. > We will have talks on Hadoop integration and some performance data related to > this. > > Please come along if you'd like to meet other people using Cassandra or would > like to learn more. > > http://www.meetup.com/Cassandra-London/events/15490570/ > > Dave > -- *Dave Gardner* Technical Architect [image: imagini_58mmX15mm.png] [image: VisualDNA-Logo-small.png] *Imagini Europe Limited* 7 Moor Street, London W1D 5NB [image: phone_icon.png] +44 20 7734 7033 [image: skype_icon.png] daveg79 [image: emailIcon.png] dave.gard...@imagini.net [image: icon-web.png] http://www.visualdna.com Imagini Europe Limited, Company number 5565112 (England and Wales), Registered address: c/o Bird & Bird, 90 Fetter Lane, London, EC4A 1EQ, United Kingdom
Re: Optimizing a few nodes to handle all client connections?
On Fri, Mar 18, 2011 at 9:55 PM, Jason Harvey wrote: > Hola everyone, > > I have been considering making a few nodes only manage 1 token and > entirely dedicating them to talking to clients. My reasoning behind > this is I don't like the idea of a node having a dual-duty of handling > data, and talking to all of the client stuff. > > Is there any merit to this thought? > > Cheers, > Jason > Technically possible but not recommended. Beside making this node a single point of failure, you assuredly add more latency to every request. Also each request has memory overhead, one node will have the sum overhead of all the requests it is not scalable. Also this node can become a bandwidth limit. One of the reasons to chose cassandra is it does NOT have a master/queen node that all requests are proxied through.
writes performance
Hello, I set up cluster with 3 nodes/ 4Gram,4cores,raid0. I did experiment with stress.py to see how fast my inserts are. The results are confusing. In each case stress.py was inserting 170KB of data: 1) stress.py was inserting directly to one node -dNode1, RF=3, CL.ONE 30 inserts in 1296 sec (30,246,246,0.01123401983,1296) 2) stress.py was inserting directly to one node -dNode1, RF=3, CL.QUORUM 30 inserts in 987 sec (30,128,128,0.00894131883979,978) 3) stress.py was inserting random into all 3 nodes -dNode1,Node2,Node3 RF=3, CL.QUORUM 30 inserts in 784 sec (30,157,157,0.00900169542641,784) 4) stress.py was inserting directly to one node -dNode1, RF=3, CL.ALL similar to case 1) --- Im not surprising about cases 2,3) but the biggest surprise for me is why cl.one is slower then cl.quorum. CL.one has less "acks", shorter time of waiting... and so on. I was looking at some blogs about "write" architecture but the reason is still not clear for me. http://www.mikeperham.com/2010/03/13/cassandra-internals-writing/ http://prettyprint.me/2010/05/02/understanding-cassandra-code-base/ Thanks for advice. Best, Peter
