So how much data can you safely fit per node using SSDs with Cassandra 3.11? How much free space do you need on your disks?
There should be some recommendations on node sizes on: http://cassandra.apache.org/doc/latest/operating/hardware.html Documentation - Apache Cassandra<http://cassandra.apache.org/doc/latest/operating/hardware.html> cassandra.apache.org The Apache Cassandra database is the right choice when you need scalability and high availability without compromising performance. Linear scalability and proven fault-tolerance on commodity hardware or cloud infrastructure make it the perfect platform for mission-critical data. Cassandra's support for replicating across multiple datacenters is best-in-class, providing lower latency for your ... ________________________________ From: Jon Haddad <j...@jonhaddad.com> Sent: Thursday, April 18, 2019 6:43:15 PM To: user@cassandra.apache.org Subject: Re: [EXTERNAL] multiple Cassandra instances per server, possible? Agreed with Jeff here. The whole "community recommends no more than 1TB" has been around, and inaccurate, for a long time. The biggest issue with dense nodes is how long it takes to replace them. 4.0 should help with that under certain circumstances. On Thu, Apr 18, 2019 at 6:57 AM Jeff Jirsa <jji...@gmail.com> wrote: > > Agreed that you can go larger than 1T on ssd > > You can do this safely with both instances in the same cluster if you > guarantee two replicas aren’t on the same machine. Cassandra provides a > primitive to do this - rack awareness through the network topology snitch. > > The limitation (until 4.0) is that you’ll need two IPs per machine as both > instances have to run in the same port. > > > -- > Jeff Jirsa > > > On Apr 18, 2019, at 6:45 AM, Durity, Sean R <sean_r_dur...@homedepot.com> > wrote: > > What is the data problem that you are trying to solve with Cassandra? Is it > high availability? Low latency queries? Large data volumes? High concurrent > users? I would design the solution to fit the problem(s) you are solving. > > > > For example, if high availability is the goal, I would be very cautious about > 2 nodes/machine. If you need the full amount of the disk – you *can* have > larger nodes than 1 TB. I agree that administration tasks (like > adding/removing nodes, etc.) are more painful with large nodes – but not > impossible. For large amounts of data, I like nodes that have about 2.5 – 3 > TB of usable SSD disk. > > > > It is possible that your nodes might be under-utilized, especially at first. > But if the hardware is already available, you have to use what you have. > > > > We have done multiple nodes on single physical hardware, but they were two > separate clusters (for the same application). In that case, we had a > different install location and different ports for one of the clusters. > > > > Sean Durity > > > > From: William R <tri...@protonmail.com.INVALID> > Sent: Thursday, April 18, 2019 9:14 AM > To: user@cassandra.apache.org > Subject: [EXTERNAL] multiple Cassandra instances per server, possible? > > > > Hi all, > > > > In our small company we have 10 nodes of (2 x 3 TB HD) 6 TB each, 128 GB ram > and 64 cores and we are thinking to use them as Cassandra nodes. From what I > am reading around, the community recommends that every node should not keep > more than 1 TB data so in this case I am wondering if it is possible to > install 2 instances per node using docker so each docker instance can write > to its own physical disk and utilise more efficiently the rest hardware (CPU > & RAM). > > > > I understand with this setup there is the danger of creating a single point > of failure for 2 Cassandra nodes but except that do you think that is a > possible setup to start with the cluster? > > > > Except the docker solution do you recommend any other way to split the > physical node to 2 instances? (VMWare? or even maybe 2 separate installations > of Cassandra? ) > > > > Eventually we are aiming in a cluster consisted of 2 DCs with 10 nodes each > (5 baremetal nodes with 2 Cassandra instances) > > > > Probably later when we will start introducing more nodes to the cluster we > can decommissioning the "double-instaned" ones and aim for a more homogeneous > solution.. > > > > Thank you, > > > > Wil > > > ________________________________ > > The information in this Internet Email is confidential and may be legally > privileged. It is intended solely for the addressee. Access to this Email by > anyone else is unauthorized. If you are not the intended recipient, any > disclosure, copying, distribution or any action taken or omitted to be taken > in reliance on it, is prohibited and may be unlawful. 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