Cassandra Cluster Expansion Criteria
Hello Folks, I’m on Cassandra 2.2.8 cluster with 14 nodes , each with around 2TB of data volume. I’m looking for a criteria /or data points that can help me decide when or if I should add more nodes to the cluster and by how many nodes. I’ll really appreciate if you guys can share your insights. Thanks/Asad
Re: Cassandra Cluster Expansion Criteria
Ideally you should maintain 50% disk space. SLA and Node load is also very important to make the decision. > On Jun 29, 2017, at 6:45 AM, ZAIDI, ASAD A wrote: > > Hello Folks, > > I’m on Cassandra 2.2.8 cluster with 14 nodes , each with around 2TB of data > volume. I’m looking for a criteria /or data points that can help me decide > when or if I should add more nodes to the cluster and by how many nodes. > > I’ll really appreciate if you guys can share your insights. > > Thanks/Asad
Re: Cassandra Cluster Expansion Criteria
Hi Asad, First, you need to understand the factors impacting cluster capacity. Some of the important factors to be considered while doing capacity planning of Cassandra are: 1. Compaction strategy: It impacts disk space requirements and IO/CPU/memory overhead for compactions. 2. Replication Factor: Impacts disk space. 3. Business SLAs and Data Access patterns (read/write) 4. Type of storage: SSD will ensure that IO is rarely a problem. You may become CPU bound first. Some trigger points for expanding your cluster: 1. Disk crunch. Unable to meet free disk requirements for various compaction strategies. 2. Overloaded nodes: tpstats/logs show frequent dropped mutations. Consistently high CPU load. 3. Business SLAs not being met due to increase in reads/writes per second. Please note that this is not an exhaustive list. ThanksAnuj Sent from Yahoo Mail on Android On Thu, Jun 29, 2017 at 7:15 PM, ZAIDI, ASAD A wrote: Hello Folks, I’m on Cassandra 2.2.8 cluster with 14 nodes , each with around 2TB of data volume. I’m looking for a criteria /or data points that can help me decide when or if I should add more nodes to the cluster and by how many nodes. I’ll really appreciate if you guys can share your insights. Thanks/Asad
Re: Cassandra Cluster Expansion Criteria
50% disk free is really only required with STCS (in size tiered compaction, if you have 4 files of a similar size, they'll be joined together - there are theoretically times when all of your data is in 4 files of the same size, and to join them together you'll temporarily double your disk space). With LCS (and TWCS), you should be able to go to 70% or so, most of the time, because that "join everything together" compaction never happens in those strategies. Keep an eye on CPU load and latencies - if you see it trending in the wrong direction beyond what you can tolerate in your SLA, you may want to consider scaling. On 2017-06-29 06:48 (-0700), Nitan Kainth wrote: > Ideally you should maintain 50% disk space. > SLA and Node load is also very important to make the decision. > > > On Jun 29, 2017, at 6:45 AM, ZAIDI, ASAD A wrote: > > > > Hello Folks, > > > > Iâm on Cassandra 2.2.8 cluster with 14 nodes , each with around 2TB of > > data volume. Iâm looking for a criteria /or data points that can help me > > decide when or if I should add more nodes to the cluster and by how many > > nodes. > > > > Iâll really appreciate if you guys can share your insights. > > > > Thanks/Asad > > - To unsubscribe, e-mail: user-unsubscr...@cassandra.apache.org For additional commands, e-mail: user-h...@cassandra.apache.org