9.8. Shared Volume Example - incomplete

jzimnowo

Hi,
In the example, there are incorrect indentations.

I would also suggest to add 'command' attribute to each container, so the Pod will be in running phase after its creation. A more complete in attachment.

Regards

chrispokorni

Hi @jzimnowo,
Thanks for your feedback. The focus on this slide may have been on the volume and volume mounts definitions and usage.
Also, in the attachment, the mount paths at the 2 containers do not have to match, they can be different while the containers still mount the same shared volume. The mount path is local to a container's environment, isolated from another container.

Regards,
-Chris

jzimnowo

Hi @chrispokorni,

About shared volume mount point, thanks for pointing this out. Indeed that makes sense.

I have further questions regarding mounting emptyDir volume:

After I connect to a given container within a Pod and inspect mounted volumes, I see that:

/ # mount|grep busy
/dev/sda1 on /busy type ext4 (rw,relatime,data=ordered)

/ # df -h |grep busy
/dev/sda1 9.6G 4.9G 4.7G 51% /busy

/ # ls -l /busy/
total 0

Could you tell me:
1) from where the limit of 9.6G volume space comes?
2) why 4.9G is already used ?

Kind regards

chrispokorni

Hi @jzimnowo,
Below is a link that explains in more detail the emptyDir volume type.

https://kubernetes.io/docs/concepts/storage/volumes/#emptydir

Then, think about the following:
Where is sda1 coming from? Is sda1 on the container, on the pod, on the node?
Once you answer these questions, you should be able to answer your 1 and 2

Regards,
-Chris

jzimnowo

Hi @chrispokorni,

Since sda1 comes from node, within a container (that is running on that node) we see node's disk capacity and usage.
Thanks for helping me
Regards