and NID for rule matching. Tools for managing ZFS snapshots of Lustre filesystems have been added, to simplify the creation, mounting, and management of MDT and OST ZFS snapshots as separate Lustre mountpoints. Lustre 2.11 was released in April 2018 and contains two significant new features, and several smaller features. The File Level Redundancy (FLR) feature expands on the 2.10 PFL implementation, adding the ability to specify mirrored file layouts for improved availability in case of storage or server failure and/or improved performance with highly concurrent reads. The Data-on-MDT (DoM) feature allows small (few MiB) files to be stored on the MDT to leverage typical flash-based RAID-10 storage for lower latency and reduced IO contention, instead of the typical HDD RAID-6 storage used on OSTs. As well, the LNet Dynamic Discovery feature allows auto-configuration of LNet Multi-Rail between peers that share an LNet network. The LDLM Lock Ahead feature allows appropriately modified applications and libraries to pre-fetch DLM extent locks from the OSTs for files, if the application knows (or predicts) that this file extent will be modified in the near future, which can reduce lock contention for multiple clients writing to the same file. Lustre 2.12 was released on December 21, 2018 and focused on improving Lustre usability and stability, with improvements the performance and functionality of the FLR and DoM features added in Lustre 2.11, as well as smaller changes to NRS TBF, HSM, and JobStats. It added LNet Network Health to allow the LNet Multi-Rail feature from Lustre 2.10 to better handle network faults when a node has multiple network interfaces. The Lazy Size on MDT (LSOM) feature allows storing an estimate of the file size on the MDT for use by policy engines, filesystem scanners, and other management tools that can more efficiently make decisions about files without a fully accurate file sizes or blocks count without having to query the OSTs for this information. This release also added the ability to manually restripe an existing directory across multiple MDTs, to allow migration of directories with large numbers of files to use the capacity and performance of several MDS nodes. The Lustre RPC data checksum added SCSI T10-PI integrated data checksums from the client to the kernel block layer, SCSI host adapter, and T10-enabled hard drives. Lustre 2.13 was released on December 5, 2019 and added a new performance-related features Persistent Client Cache (PCC), which allows