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> I have read that Cassandra needs good IO performance to do well If you're writing to disk, _anything_ will need good i/o performance to do well. That's sort
by jbellis 17y ago
> I have read that Cassandra needs good IO performance to do well
If you're writing to disk, _anything_ will need good i/o performance to do well. That's sort of the name of the game.
EBS is kind of ass for i/o, not so much for average but because you get huge latency spikes for no reason. Most cassandra installs "in the cloud" are on rackspace cloud servers instead (where you get persistent, raided local disk) for this reason.
But, you do see people like reddit and simplegeo and openx running it on ec2 and it seems to work well enough.
- jayair 17y agoThanks for clearing that up. We have been dealing with the weird spikes as well and so we were a little iffy about Cassandra on EC2.
- bd 17y agoFor the moment, Reddit is using Cassandra just for persistent cache, which implies high read/write ratio. Also it seems most of reads are done from the memory anyways (they mentioned 6GB RAM for 94% of their database in old memcachedb setting [1]). So much less stress on I/O for this particular use-case. [1] http://blog.reddit.com/2010/03/and-fun-weekend-was-had-by-all.html http://blog.reddit.com/2010/03/and-fun-weekend-was-had-by-al...