Keeping up with changes in the world of container storage is not easy. That’s why the SNIA Cloud Storage Technologies Initiative invited expert Keith Hudgins of Docker for a live webcast, “What’s New in Container Storage.” I encourage you to watch it on-demand. It’s well worth the approximately half-hour investment to get up to speed on container storage.
As promised during the live event, here are answers to the questions we received:
Q. How does the new Container Storage Interface fit in here?
A. Container Storage Interface (CSI) is one of the three persistent storage interfaces for Kubernetes. It’s also gaining a bit of traction for non-Kubernetes use as well: Pivotal and Mesos have announced their intention to use the API for support for volume use. You can learn more at the CSI main project page.
Q. Where does LXD/LXC fit into this discussion?
A. Not very well – LXC technology was used in earlier versions of Docker prior to Docker Engine 1.10. There is some provision under LXC for both persistent volumes and overlay, but I’m honestly not that familiar with the pluggable APIs for that container tech. Here’s a link to some docs for the LXD persistent storage interface.
Q. How does hardware-RAID created volumes play a role in Kubernetes? Do the hardware RAID volumes need an out-of-tree plugin for Kubernetes persistent volume?
A. Hardware RAID devices can provide volumes for containers running under Kubernetes. Like any installation, the method you use will depend on your requirements. You can use basic, in-tree drivers for most cases. Kubernetes has built-in support for NFS and iSCSI. Depending on needs, you can also build a custom driver using FlexVolume or CSI.
Q. Are there plans to add Docker support for persistent me
A.It’s a very new technology – we’re interested in the applications but it’s new. We’re waiting to see how the market matures.
Q. Is FlexVolume persistent storage?
A. Yes, absolutely. FlexVolume is one of the three persistent storage APIs available for use with Kubernetes. For deeper info on how to build FlexVolume plugins, take a look at these links:
- https://github.com/kubernetes/community/blob/master/contributors/devel/sig-storage/flexvolume.md
- https://itnext.io/how-to-create-a-custom-persistent-volume-plugin-in-kubernetes-via-flexvolume-part-1-f6d9d966e123
You can learn more about container storage in the other three container webcasts the CSTI has hosted:
- Intro to Containers, Container Storage and Docker
- Containers: Best Practices and Data Management Services
- Containers and Persistent Memory
If you have questions, please leave comments in this blog. Happy viewing!