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Resizing History Files

(changed server version 6.01 or later)

MOMI automatically creates history files when enabled. The initial size of these files are as follows:

Two methods are available to re-size the history file.  

Alter maximum extents

The utility FUP may be used, while $MOMI is running, to alter the maximum extents of the history files.   

To increase the amount of history disk space allowed, raise the MAXEXTENTS of the history file(s).  

To decrease the amount of history disk space allowed, reduce the MAXEXTENTS of the history file(s). The file system will not allow a reduction in the maximum extents below the End of File (EOF).   

On systems with limited amounts of disk space, it is suggested to start MOMI, wait a few seconds to allow the files to automatically create, and then stop MOMI. In FUP "set like" a history file, purge the old file, set the MAXEXTENTS and/or primary/secondary extent sizes, then create a new file. MOMI must be able to allocate at least one extent on every history file defined or an error will result.

See the screen Server_Info for information on how to alter the history files MAXEXTENTS from within the MOMI PC Client.

Convert file from Format 1 to Format 2

If history files were transferred from older NonStop Systems it is possible your history files were created as format 1. This old format is limited to a maximum size of approximately 2 Gigabytes. MOMI has always supported opening and reading format 2 files which are generally limited only to available disk volume space, assuming the primary and secondary extent sizes are sufficiently large.

The procedure to convert a file is to create a new file just like the old file and change a) format 2, and b) primary and secondary extent sizes. Data is transferred from the old file to the new via the FUP LOAD command.

The following steps describe how to perform the conversion. The values in green are dependent on your configuration and needs. HST01DB is used in this example sequence. Substitute the HST01DB name with the desired file on your system. Compute a primary and secondary extent size for your system:

1. Stop $MOMI.  Wait until the file is closed.

2. Start FUP and enter the following sequence of commands -

FUP

RENAME HST01DB,HST01DB1

SET LIKE HST01DB1

SET FORMAT 2

SET EXT (70000,70000)

SET MAXEXTENTS 16

CREATE HST01DB

LOAD HST01DB1,HST01DB,SORTED

3. After the load completes, exit FUP and restart MOMI. Check the EMS log to insure that the new file was accepted.

Considerations:

a) absolutely, positively, and without a doubt insure that other applications will not be impacted and that sufficient free disk space is available. Use the DSAP utility to confirm the availability of the extent sizes chosen.  Remember that total free disk space does not indicate the availability of the extent size chosen.

b) to allow a history file over 2 Gigabytes in size, consider a primary and secondary extent sizes of at least 70000. This will create a file just over 2 Gigabytes which you can then alter the maximum extents to gain additional disk space.  

c) depending on the file size and system performance, the LOAD command may take 15-20 minutes. One way to speed the process is to perform the LOAD from one disk volume to another disk volume and after the load completes FUP DUP the file back (if necessary). This may be faster than a LOAD with both input/output on the same volume.

Leave all other attributes of a MOMI file 'as is'. MOMI will not use the file if an expected attribute is changed. Check the EMS log immediately after restarting MOMI to insure that the converted history file is accepted (MOMI writes a message to the EMS log (i.e. $0) if the history file is not accepted). Fallback to the original file should the new file not be accepted.