In the end I did not use Linode Object Storage. Instead I changed provider. For the roughly same amount of money I got 160GB SSD and 8GB RAM with 2 dedicated cores from Netcup. This is the plan I purchased: https://www.netcup.eu/bestellen/produkt.php?produkt=2620 Compared to Linode it looks too good to be true, but so far it is working great. I ran Moodle Benchmark on the same site on Linode and Netcup and got a 3x better score on Netcup! With the new provider I don't have an Object Storage option any more, instead I can mount additional NFS storage (up to 1TB) and use it without any additional configuration on Moodle side, and the price for NFS is less than Linode Object Storage! I have not tested the NFS option yet. SSD is super fast (compared to Linode) but I am worried about NFS. I guess it should be fine if I move only filedir directory to NFS and keep cache and other folders on SSD. For now I will upgrade to the 320GB plan when I hit 160GB. I would like to hear if someone has experience with moodledata/filedir mounted on NFS.
We had experience with moodledata/filedir on NFS, it's difficult to tune and to get a fast and reliable connection with the NFS server. We also had a problem with an antivirus program installed that hang up our server (with NFS server) with kerneltimeouts at random moments, so be aware of that if you choose for NFS as a solution. I posted some messages in the forums here about how we configured the NFS share, that was fast enough for us: https://moodle.org/mod/forum/discuss.php?d=362709&mode=3