New Feature in the DB2 V9.7 Rotating Diagnostic and Administration Notification Logs

Transcription

1 New Feature in the DB2 V9.7 Rotating Diagnostic and Administration Notification Logs applies to: All SAP releases running DB2 9.7 for Linux, Unix and Windows. For more information, visit the Landscape Design and Architecture homepage. Summary This new feature - rotating diagnostic and administration notification logs was introduced in DB2 9.7 for Linux, UNIX and Windows. It allows customers to define the maximum amount of space to be used for diagnostic and administration notification logs and therefore prevents the overflow of the filesystem specified by the database manager configuration parameter DIAGPATH. Author: Anatoly Malchevsky Company: SAP Canada Inc. Created on: 01 June 2009 Author Bio Since joining SAP in 1999, Anatoly Malchevsky has been a member of the IBM SAP Integration and Support Centre located in the Toronto IBM Lab. He currently tests, develops and integrates new features of DB2 LUW with SAP. Through his SAP development support role and being a Customer Advocate for IBM, Anatoly assists SAP consultants and customers with activities such as troubleshooting and performance optimization 2009 SAP AG 1

2 Table of Contents Overview... 3 Working with rotating diagnostic logs... 3 Enabling rotating diagnostic logs Disabling rotating diagnostic logs... 5 Tools support for rotating diagnostic logs... 7 Best practices... 7 Related Content Copyright SAP AG 2

3 Overview IBM DB2 diagnostic logs contain information about the operation of the database. There are two types of logs: db2<instance>.nfy - intended for use by database and system administrators and db2diag.log, intended for use by DB2 Support. In releases, prior to IBM DB2 9.7, logs were allowed to grow indefinitely. If diagnostic logs are not archived, eventually they might overflow the filesystem and DB2 will loose its ability to log diagnostic information. In a worst case scenario, when the logs reside on the same filesystem as other DB2 vital data, DB2 itself will fail to function properly. Furthermore, if db2diag.log was never pruned it can contain diagnostic data for several years of operation and in a service event all the data will be transferred via ftp to SAP/IBM which can take a long time and therefore increase the response time of a service message. Huge db2diag.log overflowing customer file systems and slowing down problem determination due the large amount of data which has to be transferred is a paint point for both customers and service personnel. The new solution will also ease the daily workload of DBA s. Working with rotating diagnostic logs Enabling rotating diagnostic logs. To prevent the situation described above, a new feature was introduced in IBM DB rotating diagnostic and administration notification logs. A new database manager configuration parameter DIAGSIZE allows customer to predefine how much space can be used for all diagnostic and notification logs. The default value for DIAGSIZE is 0. It corresponds to the old behavior, i.e. only one db2diag.log and one db2<instance>.nfy logs are used and both files can grow indefinitely. Example of the update database manager configuration command: db2 update dbm cfg using DIAGSIZE 1024 DIAGSIZE is measured in Megabytes, the minimum value for the DIAGZISE parameter is 2. The maximum DIAGSIZE value can not exceed the free disk space under DIAGPATH. An SQL error SQL5130N will be returned if DIAGSIZE value exceeds the free disk space. Example of the attempt to set DIAGSIZE to a value exceeding the available free space. saplp1:db2lr1 59> db2 update dbm cfg using DIAGSIZE SQL5130N The value specified for the configuration parameter "diagsize" is not in the valid range of "2MB" to "12245MB(free space)". DIAGSIZE is not a dynamic parameter; the new value/behaviour will take effect only after an instance restart. Once DIAGSIZE is set to a non-zero value and the instance is restarted, the new logging behavior is adopted: Diagnostic messages will be written to a series of files, i.e. db2diag.0.log db2diag.###.log. The total number of logs will not exceed 10. The administration notification logs will be written to a series of files, i.e. db2<instance>.0.nfy db2<instance>.###.nfy. Total number of logs will not exceed 10. The total size of the db2diag.###.log and db2<instance>.###.nfy files will not exceed the DIAGSIZE value in MB SAP AG 3

4 Here s an example of using the DIAGSIZE, By default, DIAGSIZE is set to 0, and if we issue ls l in the db2dump directory, we see only db2diag.log and db2lr1.nfy (SAP system id is R1): saplp1:db2lr1 88> ls -l total rw-rw-rw- 1 db2lr1 dblr1adm :21 db2diag.log -rw-r db2lr1 dblr1adm :11 db2eventlog.000 -rw-rw-rw- 1 db2lr1 dblr1adm :21 db2lr1.nfy drwxrwxr-t 2 db2lr1 dblr1adm :47 events drwxrwxr-t 2 db2lr1 dblr1adm :46 stmmlog Then, we issue command saplp1:db2lr1 85> db2 update dbm cfg using DIAGSIZE 2 DB20000I The UPDATE DATABASE MANAGER CONFIGURATION command completed And restart the instance. saplp1:db2lr1 88> ls -l total rw-rw-rw- 1 db2lr1 dblr1adm :46 db2diag.0.log -rw-rw-rw- 1 db2lr1 dblr1adm :21 db2diag.log -rw-r db2lr1 dblr1adm :11 db2eventlog.000 -rw-rw-rw- 1 db2lr1 dblr1adm :46 db2lr1.0.nfy -rw-rw-rw- 1 db2lr1 dblr1adm :21 db2lr1.nfy drwxrwxr-t 2 db2lr1 dblr1adm :47 events drwxrwxr-t 2 db2lr1 dblr1adm :46 stmmlog Two new files appeared in the db2dump directory, db2diag.0.log and db2lr1.0.nfy The partition ratio between the db2diag.###.log files and the db2<instance>.###.nfy files is approximately 90% to 10%. 90% of the DIAGSIZE value is assigned to the db2diag.###.log files and 10% to the db2<instance>.###.nfy files. Back to our example, after a while, DB2 fills up db2diag.0.log and creates db2diag.1.log, db2diag.2.log and so on: saplp1:db2lr1 88> ls -l total rw-rw-rw- 1 db2lr1 dblr1adm :02 db2diag.0.log -rw-rw-rw- 1 db2lr1 dblr1adm :07 db2diag.1.log -rw-rw-rw- 1 db2lr1 dblr1adm :12 db2diag.2.log -rw-rw-rw- 1 db2lr1 dblr1adm :18 db2diag.3.log -rw-rw-rw- 1 db2lr1 dblr1adm :23 db2diag.4.log -rw-rw-rw- 1 db2lr1 dblr1adm :07 db2diag.5.log -rw-rw-rw- 1 db2lr1 dblr1adm :16 db2diag.6.log -rw-rw-rw- 1 db2lr1 dblr1adm :21 db2diag.log -rw-r db2lr1 dblr1adm :16 db2eventlog.000 -rw-rw-rw- 1 db2lr1 dblr1adm :16 db2lr1.0.nfy -rw-rw-rw- 1 db2lr1 dblr1adm :21 db2lr1.nfy drwxrwxr-t 2 db2lr1 dblr1adm :47 events drwxrwxr-t 2 db2lr1 dblr1adm :46 stmmlog Rotating diagnostics logs would never fill up the db2dump directory due to a DB2 mechanism, called early totaling ability 2009 SAP AG 4

5 When creating a new log file, DB2 always checks the available disk space, and if there is no enough space left for creating a new log file and if there are at least two rotating logs, DB2 will delete the oldest log file even if it hasn t reached the size limit yet ( the number of rotating logs hasn t reached 10 yet), so that DB2 will get some space to create the new log file. Disabling rotating diagnostic logs To get back to the old logging behavior, DIAGSIZE has to be set to 0 and the instance restarted In our example: saplp1:db2lr1 82> db2 update dbm cfg using DIAGSIZE 0 DB20000I The UPDATE DATABASE MANAGER CONFIGURATION command completed successfully SAP AG 5

6 Contents of the db2dump directory: saplp1:db2lr1 88> ls -l total rw-rw-rw- 1 db2lr1 dblr1adm :02 db2diag.0.log -rw-rw-rw- 1 db2lr1 dblr1adm :07 db2diag.1.log -rw-rw-rw- 1 db2lr1 dblr1adm :12 db2diag.2.log -rw-rw-rw- 1 db2lr1 dblr1adm :18 db2diag.3.log -rw-rw-rw- 1 db2lr1 dblr1adm :23 db2diag.4.log -rw-rw-rw- 1 db2lr1 dblr1adm :07 db2diag.5.log -rw-rw-rw- 1 db2lr1 dblr1adm :36 db2diag.6.log -rw-rw-rw- 1 db2lr1 dblr1adm :36 db2diag.log -rw-r db2lr1 dblr1adm :36 db2eventlog.000 -rw-rw-rw- 1 db2lr1 dblr1adm -rw-rw-rw- 1 db2lr1 dblr1adm drwxrwxr-t 2 db2lr1 dblr1adm drwxrwxr-t 2 db2lr1 dblr1adm :36 db2lr1.0.nfy :21 db2lr1.nfy :47 events :46 stmmlog After setting DIAGSIZE to 0, DB2 resumes logging to files db2diag.log and db2lr1.nfy. If we decide to go back to the rotating logging and set DIAGSIZE to 2 and restart the instance, loggings resumes to the latest rotating logs - files db2diag.6.log and db2lr1.0.nfy saplp1:db2lr1 88> ls -l total rw-rw-rw- 1 db2lr1 dblr1adm :02 db2diag.0.log -rw-rw-rw- 1 db2lr1 dblr1adm :07 db2diag.1.log -rw-rw-rw- 1 db2lr1 dblr1adm :12 db2diag.2.log -rw-rw-rw- 1 db2lr1 dblr1adm :18 db2diag.3.log -rw-rw-rw- 1 db2lr1 dblr1adm :23 db2diag.4.log -rw-rw-rw- 1 db2lr1 dblr1adm :07 db2diag.5.log -rw-rw-rw- 1 db2lr1 dblr1adm :21 db2diag.6.log -rw-rw-rw- 1 db2lr1 dblr1adm :36 db2diag.log -rw-r db2lr1 dblr1adm :36 db2eventlog.000 -rw-rw-rw- 1 db2lr1 dblr1adm -rw-rw-rw- 1 db2lr1 dblr1adm drwxrwxr-t 2 db2lr1 dblr1adm drwxrwxr-t 2 db2lr1 dblr1adm :36 db2lr1.0.nfy :36 db2lr1.nfy :47 events :46 stmmlog 2009 SAP AG 6

7 Tools support for rotating diagnostic logs DB2 tools like db2support and db2diag and the table UDF PD_GET_DIAG_HIST (used by the SAP transaction DB6COCKPIT) support rotating diagnostic logs. User might use the db2diag tool for reading and filtering db2 diagnostic records. There is no change in the output format as such seen by the user but they should be aware that all rotating diagnostic logs are considered by the db2diag tool if the DIAGSIZE parameter is set a non-zero value in memory. So, a command like db2diag will read all rotating db2 diagnostic logs if DIAGSIZE parameter is set to a non-zero value in memory. db2diag f (follow mode) will also support the new feature. db2diag f will read the latest rotating db2 diagnostic file in use. So, let s say we start db2diag f, it will start reading db2diag.0.log file. Then, once db2diag.1.log file is created, we switch over to db2diag.1.log file in follow mode Best practices DB2 9.7 documentation recommends setting DIAGSIZE to a value greater then 50 MB, but not to more then 80% of the free space of the db2dump directory. To prevent the loss of the diagnostic information required for analyzing a problem, I would recommend setting DIAGSIZE to 1024 (1GB). That will allow DB2 to create up to ten 10MB notification logs and up to ten 90MB diagnostic logs. Average size of a db2diag.log, (depending on the customer s workload ) in a SAP system is between 2 and 4 MB per week. So, if we set aside 1 GB of space for the diagnostic logs, it should cover situations when the database is in distress and warning/error messages are written at a high rate. Here s a table containing db2diag.log sizes in byte per week collected during the support process. This is a real-life data demonstrating the average and the maximum db2diag.log sizes encountered by the support _ _db2diag.log 1,927, _ _db2diag.log 702, _ _db2diag.log 130, _ _db2diag.log 871, _ _db2diag.log 1,115, _ _db2diag.log 560, _ _db2diag.log 239, _ _db2diag.log 226, _ _db2diag.log 18,516, _ _db2diag.log 170, _ _db2diag.log 127, _ _db2diag.log 147, _ _db2diag.log 193, _ _db2diag.log 2,472, _ _db2diag.log 3,286, _ _db2diag.log 2,454, _ _db2diag.log 2,412, _ _db2diag.log 1,652, _ _db2diag.log 1,547, _ _db2diag.log 1,825, _ _db2diag.log 1,716, _ _db2diag.log 1,710, _ _db2diag.log 1,678, _ _db2diag.log 371, _ _db2diag.log 182,687, _ _db2diag.log 19,029,678 Customers who like to keep a version of db2diag.log for a longer period can archive the logs once a week to a different filesystem/directory then db2dump, i.e. do not save information into subdirectories under the db2dump. You should not allow the db2dump directory to grow to an unmanageable size and be cluttered 2009 SAP AG 7

8 with outdated information. It will increase the size of the db2support output file and it will make problem analysis harder due to the high data volume. The db2diag tool has an option to archive diagnostic logs; it will also process rotating logs appropriately. Here s an example: saplp1:db2lr1 94> db2diag -A db2diag: Moving "/db2/lr1/db2dump//db2diag.22.log" to " /db2diag.22.log_ " db2diag: Moving "/db2/lr1/db2dump//db2diag.23.log" to " /db2diag.23.log_ " db2diag: Moving "/db2/lr1/db2dump//db2diag.24.log" to " /db2diag.24.log_ " db2diag: Moving "/db2/lr1/db2dump//db2diag.25.log" to " /db2diag.25.log_ " db2diag: Moving "/db2/lr1/db2dump//db2diag.26.log" to " /db2diag.26.log_ " db2diag: Moving "/db2/lr1/db2dump//db2diag.27.log" to " /db2diag.27.log_ " db2diag: Moving "/db2/lr1/db2dump//db2diag.28.log" to " /db2diag.28.log_ " db2diag: Moving "/db2/lr1/db2dump//db2diag.29.log" to " /db2diag.29.log_ " db2diag: Moving "/db2/lr1/db2dump//db2diag.30.log" to " /db2diag.30.log_ " db2diag: Moving "/db2/lr1/db2dump//db2diag.31.log" to " /db2diag.31.log_ " Another option would be to use a simple shell/batch file to archive the contents of the db2dump directory SAP AG 8

9 For example, #!/bin/ksh sid=${user##db2} typeset -u SID="$sid" ts=`date +%Y%m%d%H%M` print "Archiving contents of the db2dump to /db2/$user/db2dumps/${ts?}" mkdir /db2/$user/db2dumps/${ts?} mv /db2/$sid/db2dump/db2diag*.log /db2/$user/db2dumps/${ts?} mv /db2/$sid/db2dump/$user.nfy /db2/$user/db2dumps/${ts?} mv /db2/$sid/db2dump/stmmlog /db2/$user/db2dumps/${ts?} mv /db2/$sid/db2dump/events /db2/$user/db2dumps/${ts?} The script should be executed as a user db2<sid> and the directory /db2/db2<sid>/db2dumps should be created beforehand SAP AG 9

10 Related Content IBM DB2 Database for Linux, UNIX, and Windows Information Center For more information, visit the Landscape Design and Architecture homepage SAP AG 10

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