OCFS2

{{Infobox filesystem

| name = OCFS2

| full_name = Oracle Cluster file System

| developer = Oracle Corporation

| introduction_os = Linux 2.6.16

| introduction_date = March 2006

| partition_id =

| directory_struct =

| file_struct =

| bad_blocks_struct =

| max_filename_size = 255 bytes

| max_files_no =

| max_volume_size= 4 PB (OCFS2)Limited to 16TiB before 2.6.28 since it used the Linux JBD. JBD2 removes the limit.

| max_file_size= 4 PB (OCFS2)

| filename_character_set = All bytes except NUL and '/'

| dates_recorded = modification (mtime), attribute modification (ctime), access (atime)

| date_range =

| date_resolution =

| forks_streams =

| attributes =

| file_system_permissions = Unix permissions, ACLs and arbitrary security attributes (Linux 2.6 and later)

| compression = No

| encryption = No

| single_instance_storage = No

| copy_on_write = Yes

| OS = Linux

}}

The Oracle Cluster File System (OCFS, in its second version OCFS2) is a shared disk file system developed by Oracle Corporation and released under the GNU General Public License.

The first version of OCFS was developed with the main focus to accommodate Oracle's database management system that used cluster computing. Because of that it was not a POSIX-compliant file system. With version 2 the POSIX features were included.

OCFS2 (version 2) was integrated into the version 2.6.16 of Linux kernel. Initially, it was marked as "experimental" (Alpha-test) code. This restriction was removed in Linux version 2.6.19. With kernel version 2.6.29 in late 2008, more features were included into ocfs2, such as access control lists and quotas.{{cite web |title= Ocfs2 patches for merge window batch 1/3 |author= Mark Fasheh |date= December 19, 2008 |work= Linux Kernel Mailing List |url= https://lkml.org/lkml/2008/12/19/280 |access-date= October 24, 2016 }}{{cite web |title= Ocfs2 patches for merge window batch 2/3 |author= Mark Fasheh |date= December 22, 2008 |work= Linux Kernel Mailing List |url= https://lkml.org/lkml/2008/12/22/213 |access-date= October 24, 2016 }}

OCFS2 used a distributed lock manager which resembles the OpenVMS DLM but is much simpler.{{cite web |url= https://lwn.net/Articles/137278 |title= The OCFS2 filesystem |work= LWN.net |author= Jonathan Corbet |date= May 24, 2005 |access-date= October 24, 2016 }}

Oracle announced version 1.6 in November 2010 which included a copy on write feature called reflink.{{Cite web |title= What's new in Oracle Linux Part 1: OCFS2 1.6 REFLINKs |author= John Margaglione |publisher= Oracle |date= November 30, 2010 |url= https://blogs.oracle.com/devpartner/entry/whats_new_in_oracle_linux |archive-url= https://web.archive.org/web/20170510113950/https://blogs.oracle.com/devpartner/entry/whats_new_in_oracle_linux |url-status= dead |archive-date= May 10, 2017 |access-date= May 10, 2017 }}