nBackup

New Switches Added
I/O Resource Load Reduced on POSIX

New Switches Added

Four switches were added to NBackup:

  -FE <filename>   Fetch password from file
  -Z               Print version information
  -?               Help
  -D ON|OFF        Force direct I/O on or off

-FE :: Supports the feature allowing the authentication password to be fetched from a file. For details, see New -fetch_password Switch in this chapter.
-Z :: Prints the version details of the nbackup executable.
-? :: Prints a terse list of usage instructions for the switches and options.
-D :: ON option enables direct input and output operations; OFF disables them. The default settings depend on the operating system and Firebird version, as follows:

Windows service-capable platforms

ON in all versions.

POSIX

OFF in 2.0-2.0.5, 2.1-2.1.2, 2.1.4, 2.5 and higher

ON in 2.1.3 and 2.0.6, provided O_DIRECT is available; otherwise OFF. POSIX_FADV_NOREUSE is also set, if available.

Note

Using -D ON has no effect if neither O_DIRECT nor POSIX_FADV_NOREUSE is available, although no error or warning will be raised.

Note

Support for the new -D switch is also included among changes to the Services API in this version. For details, see isc_spb_nbk_direct on|off in the chapter Changes to the Firebird API and ODS.

I/O Resource Load Reduced on POSIX

An improvement has been done for POSIX versions to address a problem whereby the full backup tool of the nBackup incremental backup utility would hog I/O resources when backing up large databases, bringing production work to a standstill. Now, nBackup tries to read from the operating system cache before attempting to read from disk, thus reducing the I/O load substantially.

Note

The “cost” may be a 10 to 15 percent increase in the time taken to complete the full backup under high-load conditions.

Tracker reference CORE-2316.