Navigating the Logging environment panel
To view and model the logging environment
- On the PACLOG Main Menu, enter a subsystem ID and press Enter.
The Logging Environment panel is displayed.
ALMLG00A ============== Logging Environment - DECI =========================== Command ===> __________________________________________________________________ Type information. Then press Enter. Option . . . _ 1. Model Display current statistics & model changes 2. Actives Display active log information 3. Archives Display archive log information DASD type. . 2 1. 3380 Device type used in rate calculations 2. 3390
- Perform the following actions:
1. Model on the COMMAND line.
- Specify the DASD type in your environment.
- Press Enter.
The Logging Environment Model for SSID panel is displayed.
ALMLG01A ========== Logging Environment Model for DECI ======================= Command ===> __________________________________________________________________ Type information and press Enter. Source of highest logging rate ** . . . . . . 1 1. BSDS 2. User 3. List Optimize fields marked * for DASD archives . . 1 1. Yes 2. No Current Model Prev Expected compression ratio . . . . . __ 0-95 19 Days of log data recorded in BSDS. . ___ 1-366 0.01 Hours of log required on DASD. . . . ___ 1-999 43200 High logging rate for that period. . _____ ** 1-99999 96 Active log size (cylinders each) . . _____ * 1-99999 3 Number of active log pairs . . . . . __ * 3-93 1000 Number of entries in BSDS . . . . . _____ * 1-10000 assuming 0 Hours of archive 2 on DASD . . . . . ___ * 0-999 (0=tape) assuming 0 Hours of archive 1 on DASD 576 Total cylinders without PACLOG Total cylinders with PACLOG Cylinders saved by PACLOG
You can use the Logging Environment Model panel to change the following logging environment variables to see what effect those changes would have on the required amount of DASD and other logging environment variables:
Days of log data recorded in the BSDS
Hours of log required on DASD
Highest logging rate
Active log size in cylinders
Number of active log pairs
Number of entries in the BSDS
Hours of archive 2 on DASD
In addition, you can choose to have the modeling tool optimize your logging environment based on these criteria:
The number of days of log data that you want to record in the BSDS
The number of hours of log that you require to be kept on DASD
Logging environment panel field descriptions
The following table describes the fields on the Logging Environment Model panel:
|Source of highest logging rate|
Determines how the logging environment model obtains the highest logging rate: from the BSDS, a user entry, or a list of previous rates
|Optimize fields marked * for DASD archives|
The logging environment modeling tool can calculate the optimal size of your active logs, assuming that the archive logs will be on DASD. All fields marked with a * are included in the optimization process. To perform the optimization, select Yes in this field, enter data in the following fields, and then press Enter.
The tool initializes the following fields and then performs the optimization.
|Current||Figures in the Current column describe the current logging environment of your system as determined from the BSDS.|
|Model||Fields in the Model column allow you to change the logging environment settings in order to determine the overall effect of the changes on DASD or the logs.|
|Prev||The Prev column displays the results of the previous model you created, allowing you to compare two different scenarios.|
|Expected compression ratio||Displays expected compression of an archive log when PACLOG is used. Compression percentages of 70 to 90 percent can be expected in most circumstances.|
|Days of log data recorded in BSDS|
Displays the number of days of log data to be kept in the BSDS. BMC Software recommends that you keep a few more days than is usually necessary to allow for periods of unexpectedly high activity. For example, if you want 14 days of log available for recovery, then you should ensure that you have 17 days of log available in the BSDS.
If you select Yes in the Optimize fields marked * for DASD archives field, then you must enter the number of days you want to keep log data.
If you select No in the Optimize fields marked * for DASD archives field, then this value is calculated as follows:
|Hours of log required on DASD|
Displays the number of hours you want to retain log data on DASD. This is the length of time that you want recovery data to be available on DASD. Valid values range from 1 to 999.
If you do not archive to DASD (hours of archive 2 on DASD=0), then the value entered in this field, along with the average logging rate for this time period, is used to determine the number of days of data that is stored in the BSDS.
The value in the Current column is the value determined by the shortest length of time taken to fill all of the active log data sets.
|High logging rate for that period|
The logging environment modeling tool searches the BSDS to find the highest rate of log activity for the period of nn hours, where nn equals the value in the Hours of log required on DASD field.
You can also enter a logging rate manually or choose a logging rate from a list of high rates.
|Active log size|
Displays the active log size in cylinders
If you select Yes in the Optimize fields marked * for DASD archives field, then the size in cylinders is calculated as follows:
If you select No in the Optimize fields marked * for DASD archives field, then you must enter a value for the active log size.
|Number of active log pairs|
Displays the number of active log pairs for the DB2 subsystem. The entry in the Current column shows your current DB2 log configuration.
BMC Software recommends that you keep only three active logs if you place archive logs on DASD. In the event of a DASD failure on any log, DB2 operation can continue unimpeded with the two remaining logs while you recover the third log. Keeping only three logs also reduces redundant log information (the active data that is replicated in the archive log data sets).
If you select Yes in the Optimize fields marked * for DASD archives field, then the logging environment modeling tool sets the number of active log pairs to 3.
|Number of entries in BSDS|
Displays the number of entries kept in the BSDS. The entry in the Current column shows number of entries currently kept in the BSDS. BMC Software recommends that you always use the maximum value of 1000. The amount of DASD space occupied by these entries is only a few cylinders. If you select Yes in the Optimize fields marked * for DASD archives field, the logging environment modeling tool sets this figure to 1000.
If you do not currently keep 1000 entries in the BSDS, you can determine how changing the number of entries affects the number of days of log data recorded in the BSDS by performing log environment modeling.
|Hours of archive 2 on DAS|
Displays the amount of time that you want to retain ARCHLOG2 on DASD before migrating it to tape. The logging environment modeling tool sets this to one hour when you choose to optimize. You can also use the logging environment modeling tool to determine the impact on DASD usage if you are currently keeping more than the optimal number of hours. To view the effect of keeping a larger number of hours of ARCHLOG2 on DASD, follow these steps:
If you do not store either copy of the archive log on DASD, set this value to
|Hours of archive 1 on DASD||Displays the amount of time that ARCHLOG1 should be retained on DASD before migrating it to tape. This figure is determined by the number of hours you indicate in the Hours of log required on DASD field.|
|Total cylinders without PACLOG|
Displays the total number of cylinders required if you do not use PACLOG compression that is calculated in the following formulas.
|Total cylinders with PACLOG||Displays the total number of cylinders required if you use PACLOG compression that is calculated as the amount required without PACLOG, except that the requirements for ARCLOG1 and ARCLOG2 are reduced by the percentage you entered in the Expected compression ratio field.|
|Cylinders saved by PACLOG||Displays the number of cylinders saved by using PACLOG compression that is calculated by subtracting the cylinders required when using PACLOG from the cylinders required when not using PACLOG.|