Re: relation btw LWTs and RF
You are correct. Lightweight transactions perform a read-before-write [1]. The read phase is performed with a serial consistency which requires a quorum of nodes in the local DC (LOCAL_SERIAL) or across the whole cluster ( SERIAL) [2]. Quorum of 2 nodes is 2 nodes so RF=2 cannot tolerate a node outage. Cheers! [1] https://www.datastax.com/blog/2019/04/lightweight-transactions-datastax-enterprise [2] https://docs.datastax.com/en/cassandra-oss/3.x/cassandra/dml/dmlConfigConsistency.html#dmlConfigConsistency__table-write-consistency
Re: relation btw LWTs and RF
Ah yeah forgot to mention - I am using Cassandra 4.0-alpha4 Attila Wind http://www.linkedin.com/in/attilaw Mobile: +49 176 43556932 26.06.2020 08:06 keltezéssel, Attila Wind írta: Hey guys, Recently I ran into an interesting situation (by trying to add optimistic locking strategy to one of the tables) Which lead me eventually to the following observation. Can you confirm (or argue) this is correct when I am saying: "It is not possible to use conditional queries with ReplicationFactor = 2 with tolerating 1 node is down (out of that 2 replicas)" ? Thanks! -- Attila Wind http://www.linkedin.com/in/attilaw Mobile: +49 176 43556932
relation btw LWTs and RF
Hey guys, Recently I ran into an interesting situation (by trying to add optimistic locking strategy to one of the tables) Which lead me eventually to the following observation. Can you confirm (or argue) this is correct when I am saying: "It is not possible to use conditional queries with ReplicationFactor = 2 with tolerating 1 node is down (out of that 2 replicas)" ? Thanks! -- Attila Wind http://www.linkedin.com/in/attilaw Mobile: +49 176 43556932
Re: Encryption at rest
If you’re using AWS with EBS then you can just handle that with KMS to encrypt the volumes. If you’re using local storage on EC2, or you aren’t on AWS, then you’ll have to do heavier lifting with luks and dm-crypt, or eCryptfs, etc. If you’re using a container mechanism for your C* deployments, you might prefer options that encrypt based on directory hierarchies instead of block storage or filesystems, if you want some security isolation between co-tenants on a box. I was trying to jog my memory on the current state of the art and hit a decent summary on the Arch Linux site that you may wish to eyeball: https://wiki.archlinux.org/index.php/Data-at-rest_encryption From: Arvinder Dhillon Reply-To: "user@cassandra.apache.org" Date: Thursday, June 25, 2020 at 1:12 AM To: "user@cassandra.apache.org" Subject: Re: Encryption at rest Message from External Sender Do it at storage level. On Wed, Jun 24, 2020, 1:01 PM Jeff Jirsa mailto:jji...@gmail.com>> wrote: Not really, no. On Wed, Jun 24, 2020 at 1:00 PM Abdul Patel mailto:abd786...@gmail.com>> wrote: Team, Do we have option in open source to do encryption at rest in cassandra ?
