The NSS salvage system makes it possible to retain deleted files for a specified period of time or until space is needed. The volume salvage and file salvage subsystems function separately.
For volume salvage, the NSS volumes are automatically retained on deletion. The deleted volume can be salvaged for a period of time that is determined by the server-level Logical Volume Purge Delay setting. Administrators with the Supervisor right can salvage or purge deleted volumes at any time before the purge delay elapses.
Table 26-1 describes parameters that control the volume salvage behavior for NSS volumes. On Linux, server-level settings apply to directories and files on all NSS volumes. On NetWare, server-level settings apply to directories and files on all NSS and NetWare traditional volumes.
Table 26-1 Volume Salvage Parameters
|
Salvage Policy |
Range of Influence |
Refer to |
|---|---|---|
|
Logical Volume Purge Delay |
Server-level Default: 345600 seconds (4 days) The automatic purging delay applies to deleted NSS volumes. |
Section 26.2.1, Setting the Purge Delay for All Deleted Volumes |
|
Logical Volume Purge Delay After Continue |
Server-level Default: 900 seconds Seconds to delay purging a deleted volume after a continue. |
Section 26.2.1, Setting the Purge Delay for All Deleted Volumes |
|
Logical Volume Purge Delay After Load |
Server-level Default: 7200 seconds Seconds to delay purging a deleted volume after an NSS load if the purge delay elapses while NSS is disabled. |
Section 26.2.1, Setting the Purge Delay for All Deleted Volumes |
Salvage for directories and files is controlled by each volume’s Salvage attribute. You can enable the Salvage attribute when you create the volume, or modify the setting later in the volume’s properties. Deleted directories and files are retained and can be salvaged until space is needed in the pool where the volume resides, as determined by the pool’s available-space watermark settings. The administrator user or any user who is a trustee with the Create right can salvage deleted directories and files.
Table 26-2 describes parameters that control the file-system salvage behavior for NSS volumes.
Table 26-2 Files Salvage Parameters
|
Salvage Policy |
Range of Influence |
Refer to |
|---|---|---|
|
Salvage attribute |
Volume-level Default: Enabled |
Section 26.3, Enabling or Disabling the Salvage Attribute for an NSS Volume |
|
Immediate Purge of Deleted Files |
Server-level Default: Disabled |
Section 26.2.2, Setting the Immediate Purge of Deleted Files for All NSS Volumes |
|
Low and High Watermarks |
Pool-level Default: low 10%; high 20% Volume-level watermarks are not available. |
|
|
Purge Immediate file system attribute |
Individual directory or file where the attribute is enabled. |
Section 26.2.4, Setting the Purge Immediate Attribute for a Directory or File |
When you salvage a volume, the data and metadata is exactly the same as it was at delete time, with no changes.When salvaging deleted directories or files, the content, trustees, trustee rights, and the inherited rights filters are just as they were before the file was deleted. If the rights in the tree above the salvaged file have changed, then the inherited rights for the salvaged deleted file are calculated based on the current rights above it in the directory tree.
Purging is triggered to begin by the following events. After the deleted data enters a Purge state by manually starting a purge or by autopurging, deleted files can no longer be salvaged (do not return to a Salvageable state), even if you pause the autopurging process.
The Logical Volume Purge Delay setting times out for a deleted volume. Autopurging begins automatically and can take some time, depending on the size of the volume.
The elapsed time between the delete and the purge is called the purge delay. The server-level LogicalVolumePurgeDelay parameter applies to all NSS volumes. For information, see Section 26.2.1, Setting the Purge Delay for All Deleted Volumes.
The pool’s Low Salvage Watermark setting is reached, indicating that the amount of free space is below the administrator-specified minimum. NSS automatically purges the deleted files and directories for all volumes in the pool with a first deleted, first purged policy until the free space reaches the high watermark, or until all of the existing deleted directories and files are purged, whichever occurs first.
You configure thresholds for space-based purging on each pool. Low and high watermarks determine when to begin and stop automatic purging of deleted files to free up space on the pool. For information, see Section 26.2.3, Setting the Low and High Salvage Watermarks for Automatically Purging Deleted Directories and Files.
A user or administrator purges the deleted file or directory.
Deleted directories and files can be purged by the administrator user or by any user who is a trustee with the Erase right at any time before the automatic purge begins. For information, see Section 26.5.3, Purging Deleted Files.
An administrator purges the deleted volume.
Delete volumes can be purged by the administrator with Supervisor right to the volume. For information, see Section 26.5.3, Purging Deleted Files.
Salvage is disabled at the server level for directories and files.
Directories and files are purged immediately on deletion if the server-level ImmediatePurgeOfDeletedFiles parameter is enabled. If the Salvage attribute is enabled for a volume, this setting overrides it. For information, see Section 26.2.2, Setting the Immediate Purge of Deleted Files for All NSS Volumes.
Salvage is disabled for the individual directory or file.
If the Salvage attribute is enabled for an NSS volume, you can set the PurgeImmediate file-system attribute on individual directories and files so that they are purged immediately on deletion. For information, see Section 26.2.4, Setting the Purge Immediate Attribute for a Directory or File.
It is important to understand the differences between the salvage systems for NSS volumes as compared to NetWare® traditional volumes if you are upgrading your media to the NSS file system.
For NSS volumes, when you delete a volume, a directory (and its contents), or a file, the metadata for the deleted item is marked as deleted, but its metadata and data remain in the same physical location until it is purged or salvaged. This allows the deleted file or directory to be salvaged to the directory where it existed when it was deleted. You can also salvage a deleted directory to make its deleted files and subdirectories available for salvage. For NetWare Traditional volumes, deleted files and directories are copied to a separate storage area, unlike the method used for NSS volumes. When you delete a file on a Traditional NetWare volume, the deleted file is moved into the deleted.sav directory, which is known as the file salvage area. No record is kept of where the file originated, so salvaging files by their original directory is not possible.
When you migrate files from a Traditional volume to an NSS volume, the deleted.sav directory and its contents are not migrated; thus, they are essentially purged.
NOTE:If you upgrade a Traditional NetWare volume to an NSS volume, make sure to salvage any deleted files you want to keep before the migration.