It’s going to cause a lot of compactions - this is especially true with stcs where many of your sstables (especially the big ones) will overlap and be joined
Monitor free space (and stop compactions as needed), free memory (bloom filters during compaction will take a big chunk as you build), and of course cpu and IO - compaction touches just about everything You can test the operation impact by changing it on just one instance using JMX - compaction strategy can be set as a json string and it won’t change the cluster wide schema (or persist through reboot). -- Jeff Jirsa > On Dec 28, 2017, at 11:40 PM, "wxn...@zjqunshuo.com" <wxn...@zjqunshuo.com> > wrote: > > Hi All, > My production cluster is running 2.2.8. It is used to store time series data > with only insertion with TTL, no update and deletion. From the mail lists > seems TWCS is more suitable than STCS for my use case. I'm thinking about > changing STCS to TWCS in production. I have read the > guide(http://thelastpickle.com/blog/2016/12/08/TWCS-part1.html) someone have > posted. > > The cluster info: > UN XX.XX.44.149 939.23 GB 256 25.8% > 9180b7c9-fa0b-4bbe-bf62-64a599c01e58 rack1 > UN XX.XX.106.218 995.4 GB 256 26.0% > e24d13e2-96cb-4e8c-9d94-22498ad67c85 rack1 > UN XX.XX.42.113 905.85 GB 256 23.8% > 385ad28c-0f3f-415f-9e0a-7fe8bef97e17 rack1 > UN XX.XX.41.165 859.85 GB 256 23.1% > 46f37f06-9c45-492d-bd25-6fef7f926e38 rack1 > UN XX.XX.106.210 1.15 TB 256 26.8% > a31b6088-0cb2-40b4-ac22-aec718dbd035 rack1 > UN XX.XX.104.41 900.21 GB 256 23.6% > db08f0d7-d71f-400a-85a6-1f637fa839ee rack1 > UN XX.XX.41.95 960.89 GB 256 26.3% > cf80924b-885f-42fb-b8f8-f9e1946ec30a rack1 > UN XX.XX.103.239 919.14 GB 256 24.7% > c3f883a8-3643-46a1-ac7a-ea1b1046b400 rack1 > > I plan to use "alter table" to switch STCS to TWCS in production. My concern > is: > 1. Does the switch have a big impact on cluster performance? > 2. To ensure a smooth switch, what could I pay attention to? > > Best Regards, > -Simon
