@cupnes @toshipp Please take a look at this design PR for thin volumes when you get some time.

@sp98 I will reply tomorrow. Please wait for a while.

@sp98 @leelavg @travisn
It was determined that it would not be a problem to allow thick and thin volumes to cohabitate in 1VG. We are considering the design that can have both thick and thin pools on the same VG. This design that having multiple device class on the same VG can achieve this. However, only one thin pool can be specified in deviceClass.

For example, we could add the following new field:

• type: thin
• thinParams:
  • pool
  • spare-gb
  • overprovision-ratio

A new annotation for capacity management is generated for each device-class corresponding to the thin pool existing in the node.

Supplementary figures are provided. If you have any questions, please ask.

@sp98 @leelavg @nbalacha

Please reflect on the following comments then I approve this (and @llamerada-jp 's approval is also necessary to merge).

https://github.com/topolvm/topolvm/pull/442/files#r833957396
https://github.com/topolvm/topolvm/pull/442/files#r836245479

Please describe the possible values of OverProvisionRatio.

https://github.com/topolvm/topolvm/pull/442/files#r836222309

Please remove "omitempty" from ThinPoolConfig as well as Type.

https://github.com/topolvm/topolvm/pull/442/files#r836234886
https://github.com/topolvm/topolvm/pull/442/files#r828706602

As discussed in slack, it's not necessary to handle default.

https://github.com/topolvm/topolvm/pull/442/files#r828721468

And some additional notes.

• Does topolvm constantly poll the available capacity of the thin pools?
  • Topolvm does not poll the available capacity as of now. But we can use checkFunc() to do that. It polls every 1 minute and should not be a performance concern

As I said in another comment, it's done by notify event per 10 minutes.

• How to reload lvmd to use updated lvmd.yaml?

Please remove this item. Marking it as out-of-scope is also OK.

@satoru-takeuchi

• pardon the delay, as @sp98 is on PTO and me not having collaborator access on PR's repo the delay has happened
• pls give me a day and I'll think about any alternatives
• and thanks a lot for consolidating the decisions

As discussed in slack, it's not necessary to handle default.

• if this is the decision I'll refresh the PR that if thin targetted device-class is the default then WatchResponse.free_bytes will not be set
• I can add a check in validating device class itself however as we (not Topolvm) intend to use only thinpool targets and having a check isn't feasible
• how about no change to this for now and this'll be removed as part of dropping Ephemeral support?

@leelavg

About WatchResponse.free_bytes, it looks either of the following would be a suitable option. Costs will not be much different in either case. Which do you better?

pattern-A:
Set provisioned free bytes to WatchResponse.free_bytes when the device class is thin volume. And Set raw free bytes when device class is a thick volume (Same value as before modify).

pattern-B:
Validate so that thin volume cannot be set as default. And it will be removed as you say.

@llamerada-jp I went with a slightly modified pattern-a as below from commit thinp: updates to vgservice rpc for thinpools (as of now it's 6e49f8e)

Set provisioned free bytes [...]

• Set overprovisioned free bytes [...]

		case TypeThick:
			if dc.Default {
				res.FreeBytes = vgFree
			}
// [...]
		case TypeThin:
// [...]
// here opb is the free overprovision bytes
			opb := uint64(math.Ceil(dc.ThinPoolConfig.OverprovisionRatio*float64(tpu.SizeBytes))) - tpu.VirtualBytes
			if dc.Default {
				// TODO (leeavg): remove this after removal of support for inline ephemeral volumes
				res.FreeBytes = opb
			}
// [...]

• as a gist, we are on same page and this is also finalised IMHO

as a gist, we are on same page and this is also finalised IMHO

OK. Would you please update the comment about it at the next push?

• all, pardon the delay, all the comments on the PR are addressed
• new information is added to match the conversation happened upto now
• for rendered version pls have a look at https://github.com/sp98/topolvm/blob/thin-lv-design/docs/proposals/thin-volumes.md