RFE: "free-space headroom" or "spare-block pool"
Created by: squeed
Apologies in advance if this should be filed against lldb.
We use ql (and therefore lldb) as part of rkt's image store. The details aren't super important, but we have a CAS blobstore for container images and a small ql db for metadata.
One problem we have is if the data partition fills up (which is common enough, since by default it's on /var
), then our users can't delete images (issue). This is because we need to remove all references to a blob in the metadata before it's safe to delete the blob itself. However, since the partition is full, commits to the ql db fail.
These are not large commits - deleting fewer than 10 narrow rows - so the actual disk space requirements are very small. So, it would be nice if there was some kind of configurable headroom, especially for the WAL, so that we could make our small change, commit, and free up lots of disk space.
So, this is an RFE for a configurable free-space headroom. Writes that dip in to the headroom should not fail.