This parameter allows you to specify the fully qualified
alternate path for DB2® diagnostic
information that is used when the primary diagnostic data path, diagpath, is unavailable.
- Configuration type
- Database manager
- Applies to
-
- Database server with local and remote clients
- Client
- Database server with local clients
- Partitioned database server with local and remote clients
- Parameter type
- Configurable online
- Propagation class
- Immediate
- Default [range]
- Null [any valid path name, , '"pathname $h"', '"pathname $h/trailing-dir"', , '"pathname $n"',1 '"pathname $n/trailing-dir"', '"pathname $m"', '"pathname $m/trailing-dir"', '"pathname $h$n"',2 '"pathname $h$n/trailing-dir"', '"pathname $h$m"', or '"pathname $h$m/trailing-dir"']
Symbols - pathname
- A directory path to use when the primary diagnostic data directory
path is unavailable
- $h
- Resolves to HOST_hostname
Note: Starting in Version 10, in DB2 pureScale® environments, $h refers to the member's home host.
- $n
- Resolves
to NODEnumber
- $m
- Resolves to DIAG_number. Note
that DIAG_number is used regardless
of whether it refers to a database partition, a CF, or a member.
- /trailing-dir
- A single directory, or a directory and sub-directory to trail $h or $n
The following values are available:
- '"pathname $h"'
- '"pathname $h/trailing-dir"'
- '"pathname $n"'
- '"pathname $n/trailing-dir"'
- '"pathname $m"'
- '"pathname $m/trailing-dir"'
- '"pathname $h$n"'
- '"pathname $h$n/trailing-dir"'
- '"pathname $h$m"'
- '"pathname $h$m/trailing-dir"'
The alternate diagnostic data directory can
contain the same diagnostic data as the primary diagnostic data directory
set with the diagpath parameter. When alt_diagpath is set and the primary diagnostic data directory
becomes unavailable, diagnostic logging continues in the alternate
diagnostic data directory path specified, then resumes in its original
location when the primary diagnostic path becomes available again.
If this parameter is null and the primary diagnostic data directory
specified by the diagpath parameter is unavailable,
no further diagnostic information is written until the primary diagnostic
path becomes available again. For improved resilience, set the alternate
diagnostic data directory to point to a different file system than
the primary diagnostic data directory.
Starting in Version 10.1, the alternate diagnostic data directory path writes to
private db2diag.log for each member and CF, by default. To revert to the behavior of previous releases,
in which the diagnostic data is written to the same directory, specify
the alt_diagpath with a pathname and no token ($h, $n, or $m).
Note: - To avoid the operating system shell interpreting the $ sign on
some Linux and UNIX systems, a single quote must be placed
outside of the double quote, as shown in the syntax.
- In the CLP interactive mode, or if the command is read and executed
from an input file, the double quote is not required.
- $h, $m, and $n are case insensitive.
- The dynamic behavior for alt_diagpath does
not extend to all processes.
- The db2sysc DB2 server process can detect dynamic changes, for example,
when you issue the UPDATE DATABASE MANAGER CONFIGURATION command over an instance attachment.
- When DB2 client and application
processes start, they use the alt_diagpath configuration
parameter setting and do not detect any dynamic changes.
- On UNIX systems, if both diagpath and alt_diagpath are not
available, the db2 diagnostic message is dumped to the syslog file.
- There is no default directory for alt_diagpath configuration parameter.
- The alt_diagpath and diagpath configuration parameters are exclusive to each other. They cannot
be set to same directory path.
- If alt_diagpath (or diagpath) is unavailable that means diagnostic data dumping failed due to
an error, such as: The directory was deleted, a disk error, disk is
lost, network problems, file permission error, or disk is full.