Editing Write Anywhere File Layout (section)

{{Short description|Computer file system}}
{{more citations needed|date=March 2012}}

{{Infobox Filesystem
| full_name               = Write Anywhere File Layout
| name                    = WAFL
| developer               = [[NetApp]]
| introduction_os         =
| introduction_date       =
| partition_id            =
| directory_struct        =
| file_struct             =
| bad_blocks_struct       =
| max_filename_size       =
| max_files_no            =
| max_volume_size         = up to 100&nbsp;TB (limited by containing aggregate size; variable maximum depending on platform; limited to 16TB when using Deduplication{ONTAP 8.2 now supports dedup to max volume size supported on platform})
| max_file_size           = up to 16&nbsp;TB<ref>{{Cite web|url=https://library.netapp.com/ecmdocs/ECMP1196906/html/GUID-AA1419CF-50AB-41FF-A73C-C401741C847C.html|title=Storage limits|website=library.netapp.com}}</ref>
| dates_recorded          = [[stat (Unix)|atime, ctime, mtime]]
| date_range              =
| date_resolution         =
| forks_streams           =
| attributes              =
| file_system_permissions = UNIX permissions and ACLs
| compression             = Yes (Ontap 8.0 onwards)
| encryption              = Yes (since Ontap 9.1;<ref>{{Cite web|url=http://blog.iops.ca/?p=227|title=NetApp Volume Encryption, The Nitty Gritty &#124; IOPS.ca|date=30 November 2016 }}</ref> possible with 3rd party appliances like [[Decru]] DataFort for older versions)
| single_instance_storage = Yes (''FAS Dedup'': periodic online scans, block based;)
| OS                      = [[ONTAP]]
| copy_on_write           = Yes
|variants=}}

The '''Write Anywhere File Layout''' ('''WAFL''') is a proprietary [[file system]] that supports large, high-performance [[Redundant array of independent disks|RAID]] arrays, quick restarts without lengthy consistency checks in the event of a [[Crash (computing)|crash]] or power failure, and growing the filesystems size quickly.  It was designed by [[NetApp]] for use in its storage appliances like [[NetApp FAS|NetApp FAS, AFF]], [[ONTAP#Cloud Volumes ONTAP|Cloud Volumes ONTAP]] and [[ONTAP#ONTAP Select|ONTAP Select]].

Its author claims that WAFL is not a file system, although it includes one.<ref>{{cite web|title=Is WAFL a File System?|url=http://blogs.netapp.com/dave/2008/12/is-wafl-a-files.html |publisher=Blogs.netapp.com|archive-url=https://web.archive.org/web/20140715102135/https://communities.netapp.com/community/netapp-blogs/dave/blog/2008/12/08/is-wafl-a-filesystem|archive-date=July 15, 2014}}</ref> It tracks changes similarly to [[journaling file system]]s as logs (known as NVLOGs) in dedicated memory storage device [[non-volatile random access memory]], referred to as NVRAM or NVMEM. WAFL provides mechanisms that enable a variety of file systems and technologies that want to access [[Block (data storage)|disk blocks]].