> Can't we use LCS? Do some reading and some tests… http://www.datastax.com/dev/blog/leveled-compaction-in-apache-cassandra http://www.datastax.com/dev/blog/when-to-use-leveled-compaction
Cheers ----------------- Aaron Morton Freelance Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 15/04/2013, at 10:44 PM, Jabbar Azam <aja...@gmail.com> wrote: > I know the SSD's are a bit small but they should be enough for our > application. Out test data is 1.6 TB(including replication of rf=3). Can't we > use LCS? This will give us more space at the expensive of more I/O but SSD's > have loads of I/Os. > > > > > > Thanks > > Jabbar Azam > > > On 14 April 2013 20:20, Jabbar Azam <aja...@gmail.com> wrote: > Thanks Aaron. > > Thanks > > Jabbar Azam > > > On 14 April 2013 19:39, aaron morton <aa...@thelastpickle.com> wrote: > That's better. > > The SSD size is a bit small, and be warned that you will want to leave 50Gb > to 100GB free to allow room for compaction (using the default size tiered). > > On the ram side you will want to run about 4GB (assuming cass 1.2) for the > JVM the rest can be off heap Cassandra structures. This may not leave too > much free space for the os page cache, but SSD may help there. > > Cheers > > ----------------- > Aaron Morton > Freelance Cassandra Consultant > New Zealand > > @aaronmorton > http://www.thelastpickle.com > > On 13/04/2013, at 4:47 PM, Jabbar Azam <aja...@gmail.com> wrote: > >> What about using quad core athlon x4 740 3.2 GHz with 8gb of ram and 256gb >> ssds? >> >> I know it will depend on our workload but will be better than a dual core >> CPU. I think.... >> >> Jabbar Azam >> >> On 13 Apr 2013 01:05, "Edward Capriolo" <edlinuxg...@gmail.com> wrote: >> Duel core not the greatest you might run into GC issues before you run out >> of IO from your ssd devices. Also cassandra has other concurrency settings >> that are tuned roughly around the number of processors/cores. It is not >> uncommon to see 4-6 cores of cpu (600 % in top dealing with young gen >> garbage managing lots of sockets whatever. >> >> >> On Fri, Apr 12, 2013 at 12:02 PM, Jabbar Azam <aja...@gmail.com> wrote: >> That's my guess. My colleague is still looking at CPU's so I'm hoping he can >> get quad core CPU's for the servers. >> >> Thanks >> >> Jabbar Azam >> >> >> On 12 April 2013 16:48, Colin Blower <cblo...@barracuda.com> wrote: >> If you have not seen it already, checkout the Netflix blog post on their >> performance testing of AWS SSD instances. >> >> http://techblog.netflix.com/2012/07/benchmarking-high-performance-io-with.html >> >> My guess, based on very little experience, is that you will be CPU bound. >> >> >> On 04/12/2013 03:05 AM, Jabbar Azam wrote: >>> Hello, >>> >>> I'm going to be building a 20 node cassandra cluster in one datacentre. The >>> spec of the servers will roughly be dual core Celeron CPU, 256 GB SSD, 16GB >>> RAM and two nics. >>> >>> >>> Has anybody done any performance testing with this setup or have any >>> gotcha's I should be aware of wrt to the hardware? >>> >>> I do realise the CPU is fairly low computational power but I'm going to >>> assume the system is going to be IO bound hence the RAM and SSD's. >>> >>> >>> Thanks >>> >>> Jabbar Azam >> >> >> -- >> Colin Blower >> Software Engineer >> Barracuda Networks Inc. >> +1 408-342-5576 (o) >> >> > > >
