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WebSphere for z/OS is structured as a multiple address spaces application: it has a control region where the authorized code can run and multiple server regions where the application code runs. These server regions are dynamically started based on the amount of work by WLM services. All of these
The WebSphere for z/OS error log is a log stream that contains error messages from the Application Server. These messages are typically more detailed than you would see on the system console or in the job output of the server's address space. For example, you might see a message in the joblog of an application server saying that naming registration has failed, while the error log is more likely to have a message indicating why it failed.
WebSphere Application Server is using this error log stream to accumulate error messages. It is a funnel-type log stream, where WebSphere Application Server just
Depending on the WebSphere for z/OS configuration, you can either use Coupling Facility or Dasd-only for this log stream. Dasd-only log stream can only be either dedicated to a single instance of WebSphere for z/OS or shared across multiple instances of WebSphere for z/OS running on the same z/OS image. Coupling facility based log stream is needed if you want a single merged log stream.
The WebSphere for z/OS log stream is a funnel-type log stream and the
In case you have a spike in the messages rate you are writing on the log stream, your application should not suffer any trouble since your data will be offloaded into the offload data sets.
WebSphere for z/OS
When you activate a conversation, WebSphere for z/OS writes the environment data to an HFS file for each server instance. The
One of the
The log stream can be defined at
and so all servers in the sysplex will share the log stream and write their messages unless
Or it can be defined at
and so forth all the server instances under this server share and write to this log stream. This
Or it can be specified at Server Instance for the single instance running on a specific system to write to this particular log stream.
The definition for the WebSphere for z/OS log stream can be obtain through the customization dialog. During the installation task, one of the job that are created by the installation
As a result, the user is presented with a menu to define resources. One of the
If you select the "WebSphere Customization" section (Option 2) the user is
Figure 6-3: Sample ISPF dialog to input variables to define log stream
Name: Name of your WebSphere for z/OS error log stream that will be created.
Data class: An existing DFSMS data class for the log stream data set allocation.
Storage class: An existing DFSMS storage class for allocation of the DASD staging data set for this log stream.
HLQ for data sets: The high-level qualifier for your log stream data set name and staging data set name that will be created.
Is logstream CF resident (YN): If you want the log stream to be created on a coupling facility, specify "Y". If on DASD, specify "N".
If yes, specify structure name: If using the coupling facility, specify the coupling facility structure to be used for the log stream. Only valid if you specified Y on the previous entry.
If no, specify: logstream size: Specifies the size, in 4K blocks, of the log stream DASD data sets for the log stream being defined.
If no, specify: staging size: Specifies the size, in 4K blocks, of the DASD staging data set for the log stream being defined.
For detailed information on setting up the error log stream (including how to define the data sets, and give proper authority to server identities so they can write to it), see WebSphere Application Server for z/OS V4.0.1: Installation and Customization , GA22–7834.
After you have completed to input your variables customization job are generated in your hlq.data_set.CNTL. The member BBOERRLG contains the definition for the log stream.
If you chose to use a Coupling Facility log stream, remember that you need to define the structure to the CFRM policy first.
This task is only required if you are planning to use Coupling Facility log stream. Before running any LOGR policy, you have to make sure that the correspondent Coupling Facility structure has already been defined in the CFRM policy and that the CFRM policy has been activated in the sysplex through the SETXCF command.
Here is a set of initial samples to define the Coupling Facility structures for the WebSphere for z/OS log stream. You can use the following value as initial size and then use both RMF Coupling Facility report and the SMF88 output to validate your log stream configuration.
Example 6-43: Sample of CFRM definitions for the WebSphere log stream structure
//WASLOG JOB CLASS=A,MSGCLASS=A //POLICY
EXECPGM=IXCMIAPU //SYSPRINT DD SYSOUT=A //SYSIN DD * DATA TYPE(CFRM) STRUCTURE NAME(WAS) SIZE(8192) PREFLIST(FACIL01,FACIL02)
The following sample shows the content of the BBOERRLG member for a Coupling Facility log stream. To define a log stream, a combination of a structure and log stream definition are needed. The parameters and values that can affect performance and functionality are
Example: 0-1 BBOERRLG sample
//BBOERRLG JOB CLASS=A,MSGCLASS=A //POLICY EXEC PGM=IXCMIAPU //SYSPRINT DD SYSOUT=A //SYSIN DD * DATA TYPE(LOGR) DEFINE STRUCTURE NAME(WAS) LOGSNUM(1) MAXBUFSIZE(4096) DFINE LOGSTREAM NAME(BBO.BOSSERRS) STRUCTNAME(WAS) HLQ(LOGPLEX) AUTODELETE(YES) RETPD(1) LS_DATACLAS(LOGGER) LS_STORCLAS(LOGPLEX)
: MAXBUFSIZE in conjunction with AVGBUFSIZE is used to determine the CF structure ENTRY/ELEMENT ratio. In this case, since AVGBUFSIZE is not specified, it will be half the amount of MAXBUFSIZE value. When data is written to the CF, it's written in
Starting with OS/390 R1.3, System Logger dynamically
AUTODELETE and RETPD : WebSphere for z/OS never uses the information written on the error log: they are only for debugging scope. For this reason, to avoid a never ending accumulation of data, you must use retention period and autodelete support to delete old entries - specify these value big enough to manage this log stream on a reasonable size and to provide enough coverage in case you need to perform any debugging.
HIGHOFFLOAD : The HIGHOFFLOAD parameter is used to determine when the space dedicated to the log stream in the interim device is filling up and an offload need to be initiated to re-gain available space. HIGHOFFLOAD should be set at 80% for the error log stream at least initially and then use the SMF88 report to evaluate if this value need same tuning.
LOWOFFLOAD : The LOWOFFLOAD value defines the amount of data which may be retained in the log stream interim storage following an offload process. Since WebSphere for z/OS never reuses the data written in the lo stream, there is no point to keep any data in the log stream. For this reason, the LOWOFFLOAD value should be 0 to force all the data out of the interim device toward the offload data set.
LS_SIZE : LS_SIZE defines the allocation size for the offload data sets. It should be specified large enough to contain several offloads, possibly a day's worth.
There is no LS_SIZE value generated in the job as result of the customization dialog. Be sure that there is an allocation size for this data set specified in the associated SMS Dataclas. If LS_SIZE is not specified in the log stream definition, and an extent size is not specified in the data class pointed to by LS_DATACLAS, the value is taken from the ALLOCxx Parmlib member or set via an ACS (Automatic Class Selection) routine. The default value in ALLOCxx is 2 tracks. Refer to the z/OS MVS Initialization and Tuning Reference , SA22-7592.
It is very important to remember log stream staging and offload (log) data sets are single extent VSAM linear data sets, and the shareoptions MUST be specified as '3,3'.
The following sample shows the definition for the WebSphere for z/OS error log stream when defined as DASD-only log stream. The parameters and values that can affect performance and functionality are marked and discussed in the following section.
Example 6-44: BBOERRLG DASD-only log stream sample
//BBOERRLG JOB ,,MSGLEVEL=1,MSGCLASS=R,CLASS=A,REGION=0M, //BBORCLGS EXEC PGM=IXCMIAPU //SYSPRINT DD SYSOUT=* //SYSIN DD * DATA TYPE(LOGR) DEFINE LOGSTREAM NAME(BBO.BOSSERRS) DASDONLY(YES) HLQ(LOGPLEX) LS_SIZE(2000) STG_SIZE(2000) MAXBUFSIZE(4096) AUTODELETE(YES) RETPD(1) LS_DATACLAS(LOGGER) LS_STORCLAS(LOGPLEX)
MAXBUFSIZE : MAXBUFSIZE may be specified for a DASDONLY log stream, it defines the largest block that can be written to the log stream.
STG_DUPLEX : STG_DUPLEX(YES) with DUPLEXMODE(UNCOND) are implicitly default for DASDONLY log streams.
The WebSphere for z/OS log stream can be protected in the
Security Access Facility
(SAF) LOGSTRM class. Each WebSphere for z/OS Application Server
Example 6-45: Sample log stream security definition
RDEFINE LOGSTRM BBO.BOSSERRS UACC(READ) PERMIT BBO.BOSSERRS CLASS(LOGSTRM) ID(CBASR2) ACCESS(UPDATE) SETROPTS CLASSACT(LOGSTRM)
The log stream name defined to RACF is the name specified on the NAME parameter of the DEFINE LOGSTREAM statement in the LOGR policy.
There is no external control to dynamically enable or disable the log and also to filter the content of tracing.
The data stored is not in a readable format so WebSphere for z/OS provides a REXX EXEC (BBORBLOG) that allows you to browse the data contained in the error log stream. By default, BBORBLOG formats the error records to fit a 3270 display.
You can view the error log stream output using the BBORBLOG browser. To invoke the browser, go to ISPF option 6 and enter:
ex 'BBO.SBBOEXEC(BBORBLOG)' 'BBO.BOSSXXXX format option'
log stream name is the name of the log stream.
format option is the LRECL length of the log stream records.
This is the default. The log stream record will be formatted on a LRECL length of 80
NOFORMAT This turns off formatting. The error log message appears as one log message string in the browse file.
In this example, BBORBLOG resides in BBO.SBBOEXEC and BBO.BOSSXXXX is the LOG_STREAM_NAME that was configured in the SMUI. The browser creates a data set named 'USERID.LOG_STREAM_NAME' which will contain the formatted contents of the log stream. When the browser is executed, it does the following:
Allocates a data set called USERID.LOG_STREAM_NAME, which overwrites any duplicate data sets.
Populates the data set with the contents of the log stream.
Puts the user in browse mode on the data set.
There are no particular considerations from a recovery point of view for this log stream since there are no critical data in it.
During server initialization, WebSphere for z/OS makes an attempt to connect to the appropriate log stream. If this connection is successful, you will see the following message, which indicates the name of the log stream being used:
BOU0025I ERRORS WILL BE WRITTEN TO <logstream name> LOG STREAM FOR JOB <server name>
If, however, the server cannot connect to the log stream, the message is instead written to CERR, which puts it in the SYSOUT of the job output and WebSphere for z/OS continues to
BBOU0025I ERRORS WILL BE WRITTEN TO CERR FOR JOB <server name>
Usually there are not many considerations from a performance perspective toward the WebSphere for z/OS log stream. Measurement has been taken in both configurations, with WebSphere for z/OS running with a log stream in a coupling facility and on a DASD-only log stream, and no big difference has been noticed if recent technologies has been used for DASD placement. After your initial log stream allocation, performance data is produced in a number of forms that can be useful to determine if any adjustments is necessary to your installation:
SMF 88 data produced by the MVS System Logger
SMF 70–78 data produced by various MVS
There are several tools which aide in the analysis of log stream performance problems.
IXGRPT1 formats and
ERBRMFPP reports on the data captured in the SMF 70 -78 records
There are some fields in the SMF88 that you might want to check against this log stream: DASD SHIFT, STRUCTURE FULL, ENTRY FULL. Refer to "SMF Type 88 records and IXGRPT1 program" on page 281 for a description of these fields and what to do in case one of these conditions happens in your installation.
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