16.10 - Diagnostic Filer Startup Syntax - Teradata Database

Teradata Database Support Utilities

prodname
Teradata Database
vrm_release
16.10
created_date
June 2017
category
Configuration
featnum
B035-1180-161K
Filer diagnostic options should be used only by, or under the direction of, trained Teradata Support personnel.

The Filer diagnostic options are used to repair a corrupted file system or WAL log. Users of the diagnostic options should have thorough understanding of the Teradata file system internal structures, operation, and startup sequence.

To use the Filer diagnostic startup options, include them on the command line when starting Filer from the Supervisor window of Database Window.



The diagnostic options are described below. For an explanation of the non-diagnostic Filer startup options see Standard Startup Syntax.

Syntax Element Description
-u

Does not build the WMI, does not perform any Redo processing, but loads the MI snapshot from disk, or, if the snapshot is invalid, builds the MI.

If a problem exists such that the WAL log cannot be built successfully, first start Filer with the -x option. (If Filer does not present a command prompt, try restarting Filer using both the -x and -w options.) Repair the log, and restart Filer to perform Redo processing.

If Filer does not present a command prompt when started with the options above, restart Filer using the -u option to skip building the WAL log and performing Redo operations. Examine and repair the problem WAL cylinder indexes (WCIs) and WAL data blocks (WDBs), and restart Filer again to perform Redo processing.

If the WAL log is beyond repair, use the -u option again and run SCANDISK to determine the health of the file system before any decision is made on how to proceed next (such as deleting the complete WAL log).

-w

Executes the normal file system startup process, but ignores most errors. Redo processing continues even if errors are encountered during the Redo phase. Always builds the MI from reading CIs, rather than reading the MI from the disk snapshot copy.

If the -w option is used with another diagnostic option, the -r option need be specified only once. For example:

start filer -w -y -r 2

Use this option to clean up the WAL log and the file system as much as possible.

This option skips certain file system startup errors, such as software errors related to the Redo process and its prerequisite conditions. Read errors and other hardware-related errors are not skipped.

The Redo process attempts to process as much of the WAL log as possible, and then the rest of the normal file system startup logic is executed.

It is highly recommended to run SCANDISK after the Redo process to determine the structural integrity of the file system. See SCANDISK.

In cases where errors are encountered before the Redo phase, (for example, while building the WAL log), you can use the -w option together with another diagnostic option such as -z to skip both the errors and the Redo phase. This allows you to start Filer and possibly repair the WAL log so that subsequent file system startup and Redo processing attempts will succeed.

A log file is created for each vproc where Filer -w is invoked. You can check these files for errors and warnings. See Filer -w Error Log.

-x

Builds the WAL Master Index (WMI), but does not perform Redo processing, and does not read the MI snapshot from disk or build the MI.

Use this option to examine and repair a corrupted WAL log. The option is useful when errors are encountered during Redo processing or when building the MI.

The option provides the ability to examine and repair the WMI. It allows you to inspect the WAL log without trying to process the log or build the file system.

It is highly recommended to run SCANDISK WAL to determine the structural integrity of the WAL index structure. See SCANDISK.

Once repairs are completed, you can run Filer again to process the Redo records.

-y

Builds the WMI and performs Redo processing, and does not read the MI snapshot from disk or build the MI.

Use this option when the file system index structure is corrupt, and building the MI causes Filer to abort. This option gives you the ability to examine and repair the index structure.

Once repairs are completed, run Filer again to build the MI.

-z

Builds the WMI, does not perform Redo processing, but loads the MI snapshot from disk, or, if the snapshot is invalid, builds the MI.

Use this option when errors are encountered during Redo processing, and the WAL log may be damaged beyond repair.

You can examine the file system to determine whether it can be salvaged. You can determine whether it is possible to repair the WAL log sufficiently so that Redo processing using the -w option can complete, or to ignore the WAL log and just repair the file system index structure.

It is highly recommended to run SCANDISK WAL to determine the structural integrity of the WAL log and the file system. See SCANDISK.

-n

Does not build the WMI, does not perform Redo processing, and does not read the MI snapshot from disk or build the MI.

Use this option when serious problems exist in the file system which cause file system startup to fail in the early stages.

This option executes as little file system startup logic as possible to bypass errors so that Filer can be started. You can examine the file system to determine whether it can be salvaged. Since key global file system structures are not rebuilt in this mode, some commands, including a full SCANDISK, will be disabled.

-r vprocs Starts Filer in the -w, -u, -x, -y, -z, or -n diagnostic mode on the specified vprocs. The -r option must be used in conjunction with the other diagnostic options to limit the scope of these diagnostic modes. vprocs can be one of the following:
  • A single vproc number
  • A comma-separated list of vproc numbers
  • A range of vproc numbers in the form of start:end. For example, 2:5 represents vprocs 2, 3, 4, and 5.
  • A combination of vproc numbers and ranges of vproc numbers separated by commas

The syntax for vprocs is as follows:

Filer will start using the specified diagnostic option on the vprocs specified by the vprocs argument. Filer will start normally on the other vprocs.

If Filer is started with the -v option to run Filer only on a single vproc, the number of the vproc where Filer is running must be included in the -r vprocs specification.
-t Causes Filer invocation to create diagnostic files (dbgfil* and dbgftr*), which can be used to debug problems related to the Teradata Database File System.

Diagnostic Option Usage Notes

Running Filer with the diagnostic options is only allowed on vprocs that are in a fatal state or where the Teradata Database is not running. The -r option must be used with the diagnostic options to specify the AMPs on which Filer should run diagnostically. On other AMPs, Filer will run normally.

The -u, -x, -y, -z, and -n options are mutually exclusive; however, the -w option can be used in combination with the -u, -x, -y, -z, or -n options.

Note the distinction between the -v and the -r vprocs options of Filer:

  • -v runs Filer on a single AMP vproc. To specify the vproc on which Filer runs, the -v option of Filer is used together with the -v vproc option of the Database Window START command. If the START command -v vproc option is not specified, Filer runs on the control vproc of the node on which Filer was invoked.
  • -r vprocs runs Filer on all AMP vprocs in the system, but runs it in a diagnostic mode on the AMP vprocs specified by vprocs. The -r vprocs option must be used in conjunction with one or more of the other diagnostic Filer options. Filer runs its normal, non-diagnostic mode on the other AMPs in the system, which were not specified by -r vprocs.

When using any of the diagnostic options, SCANDISK should be run at the level that is available to the option. Initial results from SCANDISK will indicate whether the file system structures are coherent. If repairs are made based on the SCANDISK result, SCANDISK should be run again, either immediately after the repairs, or after quitting and restarting Filer with the appropriate options. This will insure that the repairs resulted in a structurally correct file system. See SCANDISK.

Some Filer commands are not available with certain diagnostic modes because these commands depend on specific file system structures which may not be built when Filer is started with those diagnostic options.

The following table shows the commands that are disabled for the various diagnostic options. Commands not listed in the table are valid in all modes of Filer.

  -u -w -x -y -z -n
CID     Disabled Disabled   Disabled
FIND     Disabled Disabled   Disabled
MI     Disabled Disabled   Disabled
MODIFY           Disabled
ROW     Disabled Disabled   Disabled
SCANDISK (Full) Disabled   Disabled Disabled   Disabled
SCANDISK WAL Disabled         Disabled
SCANDISK WMI Disabled          
TABLE     Disabled Disabled   Disabled
WABC Disabled          
WAL Disabled         Disabled
WCID Disabled         Disabled
WFIND           Disabled
WFLUSH Disabled         Disabled
WMI Disabled         Disabled
WREC Disabled         Disabled
WSUMMARY           Disabled

The diagnostic options have no direct effect on the Transient Journal (TJ). However, if manual repairs are made to the WAL log, the TJ records might also be affected.

When Filer is started with any of the diagnostic options, an informational message will be appended to the streams log(s) specifying which vprocs were affected.

Filer -w Error Log

When Filer is started with the -w option, a separate log file is created for each vproc where Filer -w is invoked. By default, the log is created in /var/opt/teradata/tdtemp. The location and name of the file is displayed on the Filer screen. The file logs any warnings and errors encountered during Filer startup on that vproc.

After Filer is started, users should check the log files for errors or warnings, and take the appropriate action to ensure that the file system structures are consistent. The log file is useful for diagnosing WAL log problems, and identifying tables that may need repair.

Example: Starting Filer in -w diagnostic mode on one vproc

The following example shows the Filer screen when Filer is invoked with the -w option. The output screen displays the location and names of the log files created.

To start Filer -w diagnostic mode on vproc 1, and have Filer run in normal mode on other vprocs in the system, type the following into the Supervisor window of Database Window:

start filer -w -r 1


Filer shows the following output in the Filer Application window of Database Window, and subsequent Filer commands are entered into this window:

Filer will be started with the -w option on the following VPROCs
   VPROC(s) 00001 (0001)

Filer will be started normally on all other VPROCs

WARNING: The Filer option that you've entered allows you to run Filer in a special diagnostic mode. Running in this mode can cause serious damage to your data if you do not understand both the internals of the file system and the basic startup sequence.  Only trained field support personnel should attempt to use these options.

Do you wish to continue?? (Y/N)
y

File System Debug Utility

    Filer

Waiting for Filer Slave tasks to start
Command has been sent to Slave tasks.


vproc  1 (0001)  response

Filer -w started on VPROC 1.
Startup information and errors will be logged
in the file /var/opt/teradata/tdtemp/filer.w1.120938.txt.

Mon Apr 07, 2011 18:19:18

 4 of 4 amps have been selected

Filer ==>

Example: Starting Filer in -w diagnostic mode on three vprocs

The following example starts Filer with the -w option on vprocs 2, 3 and 4, but starts Filer normally (without the -w option) on all other vprocs.

start filer -w -r 2, 3, 4

This command can also be invoked using the following syntax:

start filer -w -r 2:4

Example: Starting Filer in -y diagnostic mode on four vprocs

The following example starts Filer with the -y option on vprocs 1, 4 through 7, and 9, but starts Filer normally on all other vprocs.

start filer -y -r 1, 4:7, 9

Example: Starting Filer in diagnostic -v mode on one vproc

The following example starts Filer with the -n option on vproc 3 only. Since the Filer -v option (the second -v) is used, the target vproc (vproc 3 as specified by the -v 3 option) must be listed in the arguments for the -r option.

start -v 3 filer -v -n -r 3