What does 128-bit file system mean?

Question

In the introduction to ZFS file system, I saw one statement:

ZFS file system is quite scalable, 128 bit filesystem

What does 128-bit filesystem mean? What makes it scalable?

Answer 1

ZFS is a “128 bit” file system, which means 128 bits is the largest size address for any unit within it. This size allows capacities and sizes not likely to become confining anytime in the foreseeable future. For instance, the theoretical limits it imposes include 2^48 entries per directory, a maximum file size of 16 EB (2^64 or ~16 * 2^18 bytes), and a maximum of 2^64 devices per “zpool”. Source: File System Char.

The ZFS 128-bit addressing scheme and can store 256 quadrillion zettabytes, which translates into a scalable file system that exceeds 1000s of PB (petabytes) of storage capacity, while allowing to be managed in single or multiple ZFS’s Z-RAID arrays. Source: zfs-unlimited-scalability

Answer 2

TLDR it can hold much larger files then a 64 bit F. such as. EXT.

ZFS is a 128-bit file system,[85] so it can address 1.84 × 1019 times more data than 64-bit systems such as Btrfs. The limitations of ZFS are designed to be so large that they should not be encountered in the foreseeable future.

Some theoretical limits in ZFS are:

248 — Number of entries in any individual directory[86] 16 Exbibytes (264 bytes) — Maximum size of a single file 16 Exbibytes — Maximum size of any attribute 256 Zebibytes (278 bytes) — Maximum size of any zpool 256 — Number of attributes of a file (actually constrained to 248 for the number of files in a ZFS file system) 264 — Number of devices in any zpool 264 — Number of zpools in a system 264 — Number of file systems in a zpool

More here.