AdvFS
| Developer(s) | Digital Equipment Corporation |
|---|---|
| Introduced | mid 1990s |
| Structures | |
| Bad blocks | Table |
| Limits | |
| Max volume size | 16TiB |
| Max file size | 16TiB |
| Max no. of files | |
| Max filename length | 255 bytes |
| Other | |
| Supported operating systems | Tru64 Linux |
AdvFS is an opensource file system developed in the early to mid 1990s by Digital Equipment Corporation for their OSF/1 version of the Unix operating system (later Digital UNIX/Tru64 UNIX).
Its features include:
- a journal to allow for fast crash recovery
- high performance
- dynamic structure that allows an administrator to manage the file system on the fly
- on the fly creation of snapshots
- defragmentation while the domain had active users
AdvFS used a relatively advanced concept of storage pool (called file domain) and logical file systems (called file sets). A file domain was composed of any number of block devices, which could be partitions, LVM or LSM devices. A file set was a logical file system created in one file domain. Administrator can add or remove volumes from an active file domain, providing that there is enough space on the remaining file domain, in case of removal.
File sets can be balanced - file content of file sets be balanced across physical volumes. Particular files in a file set could be striped across available volumes.
Administrator can take a snapshot of any active or inactive file set. Snapshots were called clones. This allowed for easy on-line backups.
Another feature allowed administrators to add or remove block devices from a file domain, while the file domain had active users. This add/remove feature allowed migration to larger devices or migration from potentially failing hardware without a system shutdown.
Most of the advanced features required a special license.
Historically, AdvFS was developed for another operating system and ported to DEC OSF/1 by DEC engineers in Bellevue, WA. Over time, development moved to teams located in Bellevue, WA and Nashua, NH. Version were 1 version behind the OS version. Thus, DEC OSF/1 v3.2 had AdvFS v2.x, Digital UNIX 4.0 had AdvFS v3.x and Tru64 UNIX 5.x had AdvFS v4.x. It is generally considered that only v4 had matured to production level stability, with sufficient set of tools to get administrator out of any kind of trouble. Author of these lines ran AdvFS on production servers with Oracle RDBMS on all mentioned versions of Tru64 and AdvFS, without real problems.
On June 22 2008 its source code was released under GPLv2 at SourceForge in order to be compatible with the Linux kernel licence as stated in the webpage. In addition, anyone should be able to port it to the Linux kernel and get it into mainline.
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