4 ms·

I have read that Cassandra needs good IO performance to do well. So I am wondering what type of performance you guys are getting on EC2 and what are the sort of

by jayair 17y ago

I have read that Cassandra needs good IO performance to do well. So I am wondering what type of performance you guys are getting on EC2 and what are the sort of things you have done specifically in regards to it (like RAID). We are looking into Cassandra for thecadmus.com and any info would be greatly appreciated. Thanks.

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 ago
  Thanks 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 ago
    For 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...
    - jbellis 17y ago
      Very good points, thanks!
    - jayair 17y ago
      Thats a good point. My understanding is that Cassandra is ideal for write heavy scenarios. So it is interesting to see a slightly different use case.
known 17y ago
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4 ms·

I have read that Cassandra needs good IO performance to do well. So I am wondering what type of performance you guys are getting on EC2 and what are the sort of

by jayair 17y ago

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 ago
  Thanks 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 ago
    For 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...
    - jbellis 17y ago
      Very good points, thanks!
    - jayair 17y ago
      Thats a good point. My understanding is that Cassandra is ideal for write heavy scenarios. So it is interesting to see a slightly different use case.
known 17y ago
See if http://kx.com/Products/faq.php http://kx.com/Products/faq.php suits your needs.