purge expired contracts' data

[npelov]

Is it possible to clear/zero expired contracts data? If not can I do that using volumes. for example if I create another volume and remove existing one that has data will the data move to the new one or you can't remove volumes with data in active contracts? I want to be able to use the remaining space. Zeroing the data will effectively free it in zfs when using compression. Migrating the data from one volume to another will achieve the same thing

[n8mgr]

hostd assumes space allocated to a volume is reserved for it and doesn't zero data to avoid the extra IO. I wouldn't recommend doing it often, but you can create a new volume and delete the existing one to reclaim space. Data will be safely migrated to the new volume.

[npelov]

I figured that out. It's a nice workaround. But it is slow because it requires read+write. The clear would require write only.
What about setting the volume size close to allocated data (with some slack) and then returning it back as it was. Also not ideal, but will that migrate all data to the beginning of the storage file? But maybe it's the same (or maybe more) time because it has to defragment free space before reduce.
I could also split to more and smaller storage files to make it faster to cleanup. Otherwise 1TB file could be migraded for hours and hours. But then I'll have to deal with tens of 100-200GB files - it becomes a lot of work.

Ideally I could overprovision a bit and when free space gets to certain amount I could stop receiving contracts. But that requires to be able to cleanup free space. Cleanup free space could be done by external command - like hostd --cleanup, so I can run it once a week for example. Is it really that hard to do?

One related question: The storage is split to blocks (4MiB?), right? so if there is a contract of 1GB, each block of it can be placed individually to fill the gaps right? What I'm asking is fragmentation won't prevent proper fill of space?