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Showing posts from June, 2014

The world's largest family reunion ... we're all invited!

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Because we are all one global family

Taking a Full Webpage Screenshot using Firefox

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If you need to take a screenshot of the entire webpage, you can use Firefox's built in command line feature to achieve it. Press Shift + F2, a command line prompt will appear at the bottom-left part of the browser window. Type screenshot --fullpage and press enter. The page will be saved in your default download location. There are other options available on the command line which can be looked up using the command help

HANA Alert 'Check whether the database is running in log mode overwrite'

HANA system triggers regular save points which are backed up in case of a database recovery. In order to recover the database at a point-in-time, logs must be recorded between the save points. If such recording in disabled (for example to prevent file system growth), the alert 'Check whether the database is running in log mode overwrite' is triggered. The log mode must be normal in a productive environment. To fix this alert, call HANA studio --> Configuration --> global.ini --> persistence and set the parameter log_mode to normal.

Reducing memory usage of HANA DB caused by table preload

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HANA database periodically keeps track of the column attributes loaded in to the memory during a normal operation. This information is stored as table preload information, which in turn is used to load the column attributes back after each restart of the index server. This results in improvement of query execution, but it also causes the memory usage to go up. Image: http://lunaticpoet.com/in-which-i-wish-i-had-a-pensieve/ Use the following procedure to reduce the memory usage: Deactivate the preload feature of the index server temporarily by setting the reload_tables parameter in the sql section to false Deactivate the collection of table preload information in the indexserver.ini file by adding the parameter tablepreload_write_interval in the persistence section and setting the value to 0 Restart SAP HANA Execute frequently used queries to load corresponding column table attributes into memory. Manually store the above information to be used for the next restart by ex

SAP HANA Log backup grows very fast

The log backup files grow fast in /usr/sap/<sid>/HDB<Instance Number>/backup/log if the frequency of the generation of log backup files is high. This frequency is controlled by the parameter log_backup_timeout_s . Change the parameter log_backup_timeout_s back to its default 900 from HANA Studio --> Configuration --> global.ini --> persistence --> log_backup_timeout_s --> 900

Deploying .ear files

The standard deployment tool JSPM does not have an option to deploy a .ear file. The requirements to deploy ear files on SAP NetWeaver JAVA can be met using alternative tools: Using Telnet Call the telnet tool using the following command telnet localhost 5NN08 (Replace NN with the instance number. Example if your instance number is 00, the telnet port will be 50008) You will be prompted for username/password, logon with a J2EE admin user (ex: J2EE_ADMIN or Administrator) List down the server nodes using the following lsc Take note of a server node and jump to any server node using the following jump <server node> (Usually jump 0) Go to deploy application add deploy Deploy the ear file deploy <full path to ear file> on_deploy_error=stop You can also use guiconsole script located at /usr/sap/<SID>/J<nr>/j2ee/console. This script connects to telnet port and deploys the file. Using Deploy Script Change your directory to the location where deploy

df and du show different results

The values shown by df and du can be different and in some cases the sizes may vary by a large amount. df works with the file system, where as du works with the files. When the OS processes are working with files, the files' contents are dynamically changing. The actual file size might change, but the meta information of the file (inode) will remain until the process is done with the file. The df command looks at information of the inode. du looks at the information of the actual file.

Preventing Web Dispatcher from Disclosing Host Name Information

When a call to web disptcher is made and the call fails at the application server, the web dispatcher returns information such as the name of the application server, components at which the failure occurred etc. This information may be deemed as sensitive in some cases  and in case you do not wish web dispatcher to propagate this information set/change the parameter  is/HTTP/show_detailed_errors to FALSE With the parameter set to FALSE, the Web Dispatcher issues an error ID instead of the above mentioned information. For error troubleshooting purposes, systems admins can use this error ID  to look up on web dispatcher trace file (dev_webdisp)

Stack Overflow Error when starting Indexserver

When a HANA system is restarted, it will try to process the in-doubt transactions. During such processing, the stack size of the Index Server may not be sufficient and the service fails with the error: STACK OVERFLOW: SIGNAL 11 (SIGSEGV) caught To fix this error, you have to increase the stack size by editing indexserver.ini file: [threads] default_stack_size_kb = 2048 worker_stack_size_kb = 2048 Repeat the restart after adjusting the values.