Event Store Cloud unconditionally uses ZFS as the file system for data volumes. The decision to use ZFS was made based on the file system's advanced reliability guarantees, as well as data compression.
The downside is degraded performance up to 20% on the same machine size due to additional CPU load required for the file system to do all the extra work. It leads to surprises when customers compare their own cloud deployments on similar VMs and observe that ES Cloud deployments exhibit lower performance than expected.
Sometimes, compute costs are more substantial than storage costs, and customers would prefer to have bigger volumes and have their data uncompressed, rather than provisioning larger machines to compensate for additional CPU load required by ZFS.
