> Why is this in the fs layer then? Define "fs layer". ZFS has multiple layers with-in it: The "file system" that most people interact with (for things like h

> Why is this in the fs layer then? Define "fs layer". ZFS has multiple layers with-in it: The "file system" that most people interact with (for things like homedirs) is actually a layer with-in ZFS' architecture, and is called the ZFS POSIX layer (ZPL). It exposes a POSIX file system, and take the 'tradition' Unix calls and creates objects. Those objects are passed to the Data Management Unit (DMU), which then passed them down to Storage Pool Allocator (SPA) layer which actually manages the striping, redundancy, etc. * https://ibug.io/blog/2023/10/zfs-block-size/ https://ibug.io/blog/2023/10/zfs-block-size/ There was a bit of a 'joke' back in the day about ZFS being a "layering violation" because it subsumed into itself RAID, volume management, and a file system, instead of having each in a separate software packages: * https://web.archive.org/web/20070508214221/https://blogs.sun.com/bonwick/entry/rampant_layering_violation https://web.archive.org/web/20070508214221/https://blogs.sun... * https://lildude.co.uk/zfs-rampant-layering-violation https://lildude.co.uk/zfs-rampant-layering-violation The ZPL is not used all the time: one can create a block device ("zvol") and put swap or iSCSI on it. The Lustre folks have their own layer that hooks into the DMU and doesn't bother with POSIX semantics: * https://wiki.lustre.org/ZFS_OSD_Hardware_Considerations https://wiki.lustre.org/ZFS_OSD_Hardware_Considerations * https://www.eofs.eu/wp-content/uploads/2024/02/21_andreas_dilger_intel_lustre-zfs-2.4_lad12.pdf https://www.eofs.eu/wp-content/uploads/2024/02/21_andreas_di...