WAFL - Revision history

Dan Tobias at 14:39, 21 August 2019

2019-08-21T14:39:51Z

Darkstar: /* Patents */ add Google patent search URL

2015-03-26T09:55:57Z

‎Patents: add Google patent search URL

Darkstar: initial version

2015-03-26T09:48:21Z

initial version

New page

{{FormatInfo
|formattype=electronic
|subcat=Filesystem
|released=1994
}}

The [[WAFL]] filesystem (''WAFL'' stands for ''Write-Anywhere File Layout'') was developed by NetApp (then known as Network Appliance) in 1994 and is used exclusively in their FAS series filers since then. The filers run a custom operating system based on BSD called ''Data Ontap''. Only recently they started to migrate their code to a FreeBSD base system, however all of their proprietary code still runs as kernel-modules and userspace-processes atop FreeBSD.

WAFL is heavily patented and thus no significant reverse-engineering task has been started yet. Technically it is very similar to [[btrfs]]: Log-structured writes, read-only snapshots that can be made writeable, inline and post-process compression, deduplication, replication, Windows-compatible ACLs, virtual resizable volumes (similar to btrfs subvolumes) and more features are all available. It also includes its own RAID system with 1 or 2 disk parity (called ''RAID DP'', where DP stands for ''Diagonal Parity'') and uses various on-disk checksums to protect against silent data loss.

There is also a simulator available from NetApp that can be used to simulate a fully-functioning FAS filer in a virtual machine

== Links ==
*[[Wikipedia:Write_Anywhere_File_Layout|Wikipedia article]]
*[http://mysupport.netapp.com/NOW/cgi-bin/simulator Simulator] download page (NetApp account required, a "guest" type account should be sufficient)
*[http://www.netapp.com/us/media/tr-3001.pdf NetApp Technical Report TR3001] ''A Storage Networking Appliance''
*[http://hack.org/mc/texts/wafl.pdf NetApp Technical Report TR3002] ''File System Design for an NFS File Server Appliance''

== Patents ==
A lot of the inner workings of WAFL can be inferred from reading the patents filed by NetApp/Network Appliance
*[https://www.google.com/patents/US773027 US7730277] System and method for using PVBN placeholders in a flexible volume of a storage system
*[https://www.google.com/patents/US7243207 US7243207] Technique for translating a pure virtual file system data stream into a hybrid virtual volume
*[https://www.google.com/patents/US7194595 US7194595] Technique for translating a hybrid virtual volume file system into a pure virtual file system data stream
*[https://www.google.com/patents/US5819292 US5819292] Method for maintaining consistent states of a file system and for creating user-accessible read-only copies of a file system
*[https://www.google.com/patents/US20140108468 US20140108468] Methods and apparatus for changing versions of a filesystem
*[https://www.google.com/patents/US20140082281 US20140082281] Extension of write anywhere file system layout
*[https://www.google.com/patents/US20120158670 US20120158670] Fingerprints datastore and stale fingerprint removal in de-duplication environments
*[https://www.google.com/patents/US20020083037 US20020083037] Instant Snapshots

@@ Line 7: / Line 7: @@
 The [[WAFL]] filesystem (''WAFL'' stands for ''Write-Anywhere File Layout'') was developed by NetApp (then known as Network Appliance) in 1994 and is used exclusively in their FAS series filers since then. The filers run a custom operating system based on BSD called ''Data Ontap''. Only recently they started to migrate their code to a FreeBSD base system, however all of their proprietary code still runs as kernel-modules and userspace-processes atop FreeBSD.
-WAFL is heavily patented and thus no significant reverse-engineering task has been started yet. Technically it is very similar to [[btrfs]]: Log-structured writes, read-only snapshots that can be made writeable, inline and post-process compression, deduplication, replication, Windows-compatible ACLs, virtual resizable volumes (similar to btrfs subvolumes) and more features are all available. It also includes its own RAID system with 1 or 2 disk parity (called ''RAID DP'', where DP stands for ''Diagonal Parity'') and uses various on-disk checksums to protect against silent data loss.
+WAFL is heavily patented and thus no significant reverse-engineering task has been started yet. Technically it is very similar to [[btrfs]]: Log-structured writes, read-only snapshots that can be made writeable, inline and post-process compression, deduplication, replication, Windows-compatible ACLs, virtual resizable volumes (similar to btrfs subvolumes) and more features are all available. It also includes its own [[RAID]] system with 1 or 2 disk parity (called ''RAID DP'', where DP stands for ''Diagonal Parity'') and uses various on-disk checksums to protect against silent data loss.
 There is also a simulator available from NetApp that can be used to simulate a fully-functioning FAS filer in a virtual machine

@@ Line 18: / Line 18: @@
 == Patents ==
-A lot of the inner workings of WAFL can be inferred from reading the patents filed by NetApp/Network Appliance
+A lot of the inner workings of WAFL can be inferred from reading the patents [https://www.google.com/search?tbo=p&tbm=pts&hl=en&q=inassignee:%22Network+Appliance,+Inc.%22 filed by NetApp/Network Appliance]
 *[https://www.google.com/patents/US773027 US7730277] System and method for using PVBN placeholders in a flexible volume of a storage system
 *[https://www.google.com/patents/US7243207 US7243207] Technique for translating a pure virtual file system data stream into a hybrid virtual volume