sam_worm - Oracle HSM Write Once Read Many (WORM) features
SUNWqfs SUNWsamfs
The Write Once Read Many (WORM) feature is available in the Oracle HSM filesystem. The WORM feature allows you to retain files for a specified period of time. This period can be as long as the life of the system or as short as 1 minute, and is stored in filesystem metadata. A Oracle HSM filesystem is made "WORM-capable" by one of the following mount options:
worm_capable
worm_lite
worm_emul
emul_lite
These mount options control the actions needed to enable WORM files and directories and the actions that can be performed on these files and directories once they're made WORM-capable. A directory is made WORM capable when the WORM trigger is applied to it. Likewise, a file is made into a WORM file when the WORM trigger is applied to an ordinary file in a WORM capable directory. Note, the file must be fully populated before the trigger is applied as the file's contents can't be modified afterward. Oracle HSM supports two WORM triggers, they are:
chmod 4000 filename
chmod -w filename
The "chmod 4000" command is the WORM trigger when the "worm_capable" or "worm_lite" mount option is used. Removing the write permissions, that is, the transition from a writable to read-only file is the WORM trigger when the "worm_emul" or "emul_lite" mount option is used.
When the WORM trigger is applied to a file or directory, a period of time, known as a retention period, is associated with it. The retention period is used to indicate how long a file will be protected from change. When a file has an active retention period, it can not be renamed, removed, or have its path altered. When the period expires, a file may only be removed or have its retention period extended.
The retention period can be set or extended by advancing the access time of the associated file or directory. The difference between the current time and the access time is used as the retention period. Setting the retention period on a directory sets the default retention period for files created in the directory. This period is applied to files if a retention period is not specified when the WORM trigger is used. In addition, this period is inherited by all sub-directories created in this directory. Note, a directory's default retention period can be increased or decreased, while a file's period can only be increased.
A default retention period can also be set using the mount option "def_retention=n", where "n" is a simple integer value representing minutes or a variable format MyNdOhPm in which M, N, O, P are arbitrary non-negative integers and the characters y, d, h, m represent the number of years, days, hours, and minutes. The default retention period is applied to a directory if a retention period is not specified when the WORM trigger is applied. If no default period is given, the system default of 30 days is used.
The WORM lite option relaxes some of the restrictions on WORM files. This is enabled when the "worm_lite" or "emul_lite" mount options are used. Only the system administrator is allowed to carry out the following actions:
Shorten retention periods on files
Remove retained files before their period expires
Rebuild "lite" enabled volumes (using sammkfs)
WORM Lite is a solution for document management and retention policies requiring data retention guarantees without the strict constraints that full WORM implementations place on systems.
