This section describes how to complete the tasks associated with operating and customizing VMDSS.
There are three VMDSS specifications that you can set for storage pools:
The default settings are that every storage pool will use data spaces, a working storage residency priority of 3, and striping.
| Note: | A storage pool used only for internal dbspaces and which as a dbextent on a virtual disk cannot be used with data spaces turned on for that pool. This storage pool must be specified with the BLK and SEQ options in the storage pool specification file. See Appendix A, Storage Pool Specification File Format. |
You can change these settings either at database startup, or (except for the first one) dynamically while the database is running.
To change the storage pool specifications of your database at startup, you need to create a storage pool specification file. You can read the next few sections to learn how to do this, or you can refer to Appendix A, Storage Pool Specification File Format for a summary of the file's syntax.
At startup, the application server looks for the storage pool specification file. It should have a file name that corresponds to your database's server_name, a file type of ARISPOOL and a file mode of *.
If you want to use a different file name or file type, enter a CMS FILEDEF command to identify a file as the storage pool specification file. For example:
FILEDEF ARISPOOL DISK SPSPEC FILE A
where SPSPEC FILE A identifies the storage pool specification file. The FILEDEF syntax is:
>>-FILEDEF ARISPOOL DISK--filename--filetype--filemode--------->< |
Add your specifications to the specification file as described below, and start the application server. If you want to add or change any specifications, you must:
To change this setting for a particular storage pool, add a line to the specification file to specify either Data Spaces Support (DS) or standard DASD I/O (BLK). (DS is the default.)
| Note: | If your internal dbspaces reside in a storage pool which contains a virtual disk, you MUST specify BLK and SEQ for that storage pool. A virtual disk cannot be mapped to a Data Space. |
For example, consider a database with five storage pools. To use Data Spaces Support for storage pool 1 and standard DASD I/O for pools 2 to 5, your specification file would look like:
-- Storage Pool Specification File
1 DS -- This line turns on Data Spaces Support for pool 1
2-5 BLK -- This line turns off Data Spaces Support
-- for pools 2 to 5
|
The text is optional comments. If you add any comments, precede them by two dashes.
Note that DS is the default parameter, so you can also code the file like:
-- Storage Pool Specification File
2-5 BLK -- This line turns off Data Spaces Support
-- for pools 2 to 5
|
For information on when to use data spaces with storage pools, refer to Storage Pool.
To set the storage residence priority of a storage pool that uses Data Spaces Support, add an integer (from 1 to 5) to the end of the DS parameter in your specification file. (3 is the default.)
For example, to use priority 1 with pools 3 and 4, priority 3 with pool 2, and priority 4 with pool 5, your specification file would look like:
-- Storage Pool Specification File
1 BLK -- This line turns off Data Spaces Support for pool 1
2 DS -- This line uses residency priority 3 for pool 2
3-4 DS1 -- This line uses residency priority 1 for pools 3 and 4
5 DS4 -- This line uses residency priority 4 for pool 5
|
Pool 1 is not using Data Spaces Support, so it is not assigned any priority. Pool 2 is using the default value, so the integer 3 does not have to be included.
For a description of the five priorities and how to choose one, refer to Choosing Storage Residence Priorities.
To turn striping on for a particular storage pool, add the three-letter code STR to the end of the line for that pool. To turn it off, add the code SEQ.
For example, to turn striping on for storage pools 1, 3, and 5, and to turn it off for pools 2 and 4, your specification file would look like:
-- Storage Pool Specification File
1 BLK STR -- Striping turned on
2 DS SEQ -- Striping turned off
3 DS1 STR -- Striping turned on
4 DS1 SEQ -- Striping turned off
5 DS4 -- Striping left on by default
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For information on when to use striping, refer to Using Striping.
You can display your current storage pool specifications from the operator console, or through ISQL, with the SHOW POOL operator command.
For example, the following screen shows you that pool 2 is using Data Spaces Support with a storage residency priority of 3, and striping:
+--------------------------------------------------------------------------------+ |show pool 2 | | | |POOL NO. 2: NUMBER OF EXTENTS = 6 DS3 STR | | | |EXTENT TOTAL NO. OF NO. OF NO. OF % | | NO. PAGES PAGES USED FREE PAGES RESV PAGES USED | | 1 200070 55821 144249 27 | | 2 200070 54645 145425 27 | | 3 200070 56965 143105 28 | | 4 200070 56336 143734 28 | | 5 200070 55210 144860 27 | | 6 200070 56267 143803 28 | |TOTAL 1200420 335244 865176 20 27 | |ARI0065I Operator command processing is complete. | +--------------------------------------------------------------------------------+
For a detailed description of this command, refer to the DB2 Server for VSE & VM Operation manual.
Once the application server is running, if you want to change the setting for Data Spaces Support (DS or BLK) you must shut down and restart the database manager as described in Changing Storage Pool Specifications at Startup. However, the two other specifications --working storage residency priority and striping-- can be changed dynamically by issuing the SET POOL command from the operator console. For example:
+--------------------------------------------------------------------------------+ |set pool 1 ds2 seq | |ARI0065I Operator command processing is complete. | |show pool 1 | | | |POOL NO. 1: NUMBER OF EXTENTS = 2 DS2 SEQ | | | |EXTENT TOTAL NO. OF NO. OF NO. OF % | | NO. PAGES PAGES USED FREE PAGES RESV PAGES USED | | 1 855 74 781 8 | | 2 855 47 808 5 | |TOTAL 1710 121 1589 20 7 | |ARI0065I Operator command processing is complete. | +--------------------------------------------------------------------------------+
| Note: | Any changes you make using the SET POOL command are only in effect while the application server is running. If you stop and restart the application server, it will use the settings in the storage pool specification file, which are unchanged by the SET POOL command. |
For a detailed description of the SET POOL command, refer to the DB2 Server for VSE & VM Operation manual.