I have deleted a Ceph filesystem, and copied the metadata and data pools. Is it possible to recreate the filesystem from these copies?
I can't comment yet due to my reputation, so don't necessarily consider this a full qualified answer.
Since your question is not entirely clear to me, I assume you mean creating a new CephFS containing the pre-existing data?
My short answer is "yes". It depends on various circumstances, of course, but if you have a dump of the data you should be able to create a new filesystem with the same content.
About a year ago we had to recreate our CephFS because of a faulty pool configuration regarding Placement Groups. Since you can't change those settings we had to recreate the whole filesystem. But that went quite smoothly, I can't remember the details but this didn't cause us any trouble. I believe this doesn't even require the metadata. Creating a new CephFS will also create two new pools and then you can replay your data back into the new CephFS.
If you mean to restore the exact same CephFS from the backup data I don't think that's possible because you deleted it. I may be wrong though, you could ask the ceph-users mailing list for further advice.