Editing NTFS (section)

== Scalability ==
NTFS is optimized for 4&nbsp;[[kilobyte|KB]]{{efn|name=units}} [[Data cluster|clusters]], but supports a maximum cluster size of 2{{nbsp}}[[megabyte|MB]]{{efn|name=units}}. (Earlier implementations support up to 64{{nbsp}}KB)<ref name="MS-FSA_id_1">{{cite web |url= https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fsa/4e3695bd-7574-4f24-a223-b4679c065b63#Appendix_A_1 |title= Appendix A: Product Behavior |work= [MS-FSA]: File System Algorithms |publisher= Microsoft|date= 2018-09-12 |access-date= 2018-10-01 |quote= NTFS uses a default cluster size of 4 KB, a maximum cluster size of 64 KB on Windows 10 v1703 operating system and Windows Server 2016 and prior, and 2 MB on Windows 10 v1709 operating system and Windows Server 2019 and later, and a minimum cluster size of 512 bytes.}}</ref> The maximum NTFS volume size that the specification can support is {{nowrap|2<sup>64</sup> − 1}} clusters, but not all implementations achieve this theoretical maximum, as discussed below.

The maximum NTFS volume size implemented in Windows XP Professional is {{nowrap|2<sup>32</sup> − 1}} clusters, partly due to partition table limitations. For example, using 64{{nbsp}}KB clusters, the maximum size Windows XP NTFS volume is 256{{nbsp}}[[terabyte|TB]] minus 64{{nbsp}}[[kilobyte|KB]]. Using the default cluster size of 4{{nbsp}}KB, the maximum NTFS volume size is 16{{nbsp}}TB minus 4{{nbsp}}KB. Both of these are vastly higher than the 128{{nbsp}}[[gigabyte|GB]]{{efn|name=units}} limit in [[Windows XP#Service Pack 1|Windows XP SP1]]. The size of a partition in the Master Boot Record (MBR) is limited to 2 TiB with a hard drive with 512-byte physical sectors,<ref>{{cite web |title=Windows support for hard disks that are larger than 2 TB |website=[[Microsoft Learn]] |date=2013-06-26 |url=https://learn.microsoft.com/en-us/troubleshoot/windows-server/backup-and-storage/support-for-hard-disks-exceeding-2-tb |access-date=2024-08-08}}</ref><ref>{{cite web |title=Default cluster size for NTFS, FAT, and exFAT |url=https://support.microsoft.com/en-us/topic/default-cluster-size-for-ntfs-fat-and-exfat-9772e6f1-e31a-00d7-e18f-73169155af95|website=Microsoft Support|archive-url=https://web.archive.org/web/20240309213220/https://support.microsoft.com/en-us/topic/default-cluster-size-for-ntfs-fat-and-exfat-9772e6f1-e31a-00d7-e18f-73169155af95|archive-date=2024-03-09|url-status=dead}}</ref> although for a 4 KiB physical sector the MBR partition size limit is 16 TiB. An alternative is to use multiple [[GUID Partition Table]] (GPT or "dynamic") volumes for be combined to create a single NTFS volume larger than 2 TiB. Booting from a GPT volume to a Windows environment in a Microsoft supported way requires a system with [[Unified Extensible Firmware Interface]] (UEFI) and 64-bit{{Efn|Can also be 32-bit, provided that the firmware and operating system loader are size-matched.}} support.<ref>{{cite web|url=http://www.rodsbooks.com/gdisk/booting.html|title=Booting from GPT|website=Rodsbooks.com|access-date=22 September 2018}}</ref> GPT data disks are supported on systems with BIOS.

The NTFS maximum theoretical limit on the size of individual files is 16{{nbsp}}[[Exabyte|EB]]{{efn|name=units}}<ref>{{Cite web|title=NTFS vs FAT vs exFAT – NTFS.com|url=https://www.ntfs.com/ntfs_vs_fat.htm|access-date=2021-01-19|website=www.ntfs.com}}</ref> ({{nowrap|16 × 1024<sup>6</sup>}} or {{nowrap|2<sup>64</sup> bytes}}) minus 1{{nbsp}}KB, which totals 18,446,744,073,709,550,592 bytes. With [[Windows 10]] version 1709 and [[Windows Server 2019]], the maximum ''implemented'' file size is 8{{nbsp}}PB{{efn|name=units}} minus 2{{nbsp}}MB or 9,007,199,252,643,840 bytes.<ref name="MS-FSA_id_1"/>