On Thu, Jun 7, 2018 at 9:12 AM, Nitan Kainth <nitankai...@gmail.com> wrote:
> Riccardo, > > Simplest method can be is to add VPC as an additional datacenter to > existing cluster; once New DC has synced up all data, just switch over your > application. Only caveat is that there should be enough network bandwidth > between EC2 and VPC. > > Horizontal scaling will help to some extent. > > Changing snitch will cause data movement but for new DC, I believe you can > chose. Leaving others comment. > If you change the snitch, and the data ownership changes, you run the risk of violating at least consistency guarantees, if not outright losing data. Changing the snitch is only something you should attempt if you understand the implications. Cassandra does NOT re-stream data to the right places if/when you change a snitch. > > With EBS, use right instance where IOPs are as high as possible. > Generally, SSDs IOPs are 75K; what is best for you depends on workload. I > have seen 20K IOPs supporting production loads in reasonable cluster. > This is very much workload dependent. I know of people running thousands of nodes / petabytes of EBS on 4T GP2 volumes which provide 10k iops, and they RARELY go above 1k iops during normal use patterns. - Jeff > > On Thu, Jun 7, 2018 at 6:20 AM, Riccardo Ferrari <ferra...@gmail.com> > wrote: > >> Dear list, >> >> We have a small cluster on AWS EC2-Classic and we are planning to move it >> to a VPC. >> >> I know this has been discussed few times already including here: >> https://mail-archives.apache.org/mod_mbox/cassandra-user/201 >> 406.mbox/%3CCA+VSrLopop7Th8nX20aOZ3As75g2jrJm3ryX119dekLYNHq >> f...@mail.gmail.com%3E - Thanks Alain RODRIGUEZ! >> or here: >> http://grokbase.com/t/cassandra/user/1498y74hn7/moving- >> cassandra-from-ec2-classic-into-vpc - Thanks Ben Bromhead! >> >> However I can't find anyone suggesting ClassicLink to perform such >> migration, maybe because was recent addition compared to those posts. So >> current status is: >> >> >> - 3 nodes : m1.xlarge (ephemeral storage) >> - Cassandra 3.0.8 >> - Few keyspaces with {'class': 'SimpleStrategy', >> 'replication_factor': '3'} >> - endpoint_snitch: Ec2Snitch >> - connectivity on private ips (local_address, rpc_address, no >> broadcast_address) >> - average load pretty high (we need to scale up) >> - vnodes >> >> My idea is to migrate: >> >> - Add intances on to the existing cluster (1 by 1): >> - Same cassandra version >> - Same cluster name >> - Seed list from ec2 classic list >> - Run repair and cleanup >> - Update seed list (cassandar config and services) >> - Decommision old instances (1 by 1) >> - Run repair and cleanup again >> >> >> Question time: >> >> - What is the best approach, in 2018, for migrating a cluster from >> EC2Classic to VPC with 0 downtime? >> - Should we scale up before or during the migration? I know I should >> expect some load from data streaming, at the same time we're adding >> capacity. >> - We would like to migrato to GossipingPropertyFileSnitch, can we mix >> them? >> - Any gothca? >> - We are thinking to move to EBS (due to cluster size and >> snapshotting caoabilities). Any hardware reccomendation? >> >> Any suggestion is much appreciated! >> >> >> >> >
