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Archives for December 2019

Oracle SQL Script to Detect Tablespace Fragmentation

By admin

The following is a script that will determine how many extents of contiguous free space you have in Oracle as well as the total amount of free space you have in each tablespace. From these results, you can detect how fragmented your tablespace is. The ideal situation is to have one large free extent in your tablespace. The more extents of free space there are in the tablespace, the more likely you will run into fragmentation problems. The size of the free extents is also very important. … [Read more...] about Oracle SQL Script to Detect Tablespace Fragmentation

Filed Under: oracle

MySQL Table Maintenance – InnoDB, MyISAM, MEMORY, ARCHIVE

By admin

InnoDB Table Maintenance If a table check indicates problems, restore the table to a consistent state by dumping it with mysqldump, dropping it, and re-creating it from the dump file. In the event of a crash of the MySQL server or the host on which it runs, some InnoDB tables might be in an inconsistent state. InnoDB performs auto-recovery as part of its startup sequence. Use CHECK TABLE or a client program to find inconsistencies, incompatibilities, and other problems. Restore a table by … [Read more...] about MySQL Table Maintenance – InnoDB, MyISAM, MEMORY, ARCHIVE

Filed Under: mysql, MySQL Cluster

Understanding mysqlcheck and myisamchk utilities

By admin

mysqlcheck Client Program In some cases, mysqlcheck is more convenient than issuing SQL statements directly. For example, if you provide it with a database name as its argument, mysqlcheck determines what tables the database contains and issues statements to process them all. You do not need to provide explicit table names as arguments. Also, because mysqlcheck is a command-line program, you can easily use it in operating system jobs that perform scheduled maintenance. mysqlcheck is a … [Read more...] about Understanding mysqlcheck and myisamchk utilities

Filed Under: mysql, MySQL Cluster

CentOS/RHEL – How to Remove stale ISCSI Target Node Information from ISCSI Initiator Server

By admin

The Problem Stale ISCSI target connections which are still present on Initiator node can lead to various issues like: 1. hung iscsid service which can lead to global outage. 2. flood of messages error like: messages:Jun 3 13:58:00 server1 iscsid: iscsid: Connection5:0 to [target: iqn-name, portal: ip-here,3260] through [iface: default] is shutdown. messages:Jun 3 13:58:00 server1 iscsiadm: iscsiadm: Could not login to [iface: default, target: iqn-name, portal: ip-here,3260]. messages:Jun … [Read more...] about CentOS/RHEL – How to Remove stale ISCSI Target Node Information from ISCSI Initiator Server

Filed Under: CentOS/RHEL 6, CentOS/RHEL 7, Linux

CentOS/RHEL 6 Kernel Panic – “Out of memory” kernel parameter panic_on_oom is enabled

By admin

The Problem CentOS/RHEL 6 system reboot due too out of memory error: DUMPFILE: vmcore [PARTIAL DUMP] CPUS: 2 DATE: Mon Feb 29 05:28:02 2016 UPTIME: 33 days, 09:45:55 LOAD AVERAGE: 1.88, 1.52, 1.41 TASKS: 218 NODENAME: localhost RELEASE: 2.6.32-431.el6.x86_64 VERSION: #1 SMP Sun Nov 10 22:19:54 EST 2013 MACHINE: x86_64 (3000 Mhz) MEMORY: 8 GB PANIC: "Kernel panic - not syncing: Out of memory: system-wide panic_on_oom is enabled" PID: 31010 COMMAND: "java" … [Read more...] about CentOS/RHEL 6 Kernel Panic – “Out of memory” kernel parameter panic_on_oom is enabled

Filed Under: CentOS/RHEL 6, Linux

How to enable core dump for Applications on CentOS/RHEL

By admin

1. In CentOS/RHEL core file creation is disabled by default. To enable it, executing the below command: # ulimit -S -c unlimited > /dev/null 2>&1 then execute the program in the same shell environment. 2. To enable it permanently, please follow steps below: - Edit /etc/security/limits.conf. # vi /etc/security/limits.conf * soft core unlimited The '*' is used to enable coredump size to unlimited to all users. - Edit /etc/sysctl.conf to add the path of the core dump and file … [Read more...] about How to enable core dump for Applications on CentOS/RHEL

Filed Under: CentOS/RHEL 6, CentOS/RHEL 7, Linux

How to add additional language support in CentOS/RHEL

By admin

Question: How to add additional language support in CentOS/RHEL? To add specific language support in CentOS/RHEL, you need firstly confirm the correct language group name by "yum grouplist" command. # yum grouplist The available language groups will be displayed in yum output as below: # yum grouplist Loaded plugins: refresh-packagekit, rhnplugin Setting up Group Process Installed Groups: ... Installed Language Groups: Arabic Support [ar] Armenian Support [hy] ... Available … [Read more...] about How to add additional language support in CentOS/RHEL

Filed Under: CentOS/RHEL 6, CentOS/RHEL 7, Linux

What are “segfault” messages in /var/log/messages file

By admin

This post explains how to analyse the segfault message in message file and to identify the problem in application or operating system side. What is "segfault"? A segmentation fault (often shortened to segfault) or access violation is a fault raised by hardware with memory protection, to notify operating system (OS) about a memory access violation. The Linux kernel will response it by performing some corrective action, generally passing the fault to the offending process by sending the … [Read more...] about What are “segfault” messages in /var/log/messages file

Filed Under: CentOS/RHEL 5, CentOS/RHEL 6, CentOS/RHEL 7, Linux

Unable to login with GUI on CentOS/RHEL 7

By admin

The Problem can't login to the system via GUI On CentOS/RHEL 7. Also, gdm segfault with below error after which unable to login to GUI. kernel: gdm-simple-slav[4172]: segfault at 0 ip 00007f93d911c7df sp 00007fffecadaac0 error 4 in gdm-simple-slave[7f93d910a000+4a000] kernel: gdm-simple-slav[2645]: segfault at 0 ip 00007f9781f7d7df sp 00007fff672c6980 error 4 in gdm-simple-slave[7f9781f6b000+4a000] The Solution For new installation of CentOS/RHEL 7 ,GUI doesnot come with default … [Read more...] about Unable to login with GUI on CentOS/RHEL 7

Filed Under: CentOS/RHEL 7, Linux

rpm: error while loading shared libraries: invalid ELF header

By admin

The Problem rpm commands issue the following error: rpm: error while loading shared libraries: /usr/lib64/liblzma.so.0: invalid ELF header The Solution In this instance, either liblzma.so or the link to it (/usr/lib64/liblzma.so.0) had gotten overwritten. $ rpm -qa | grep binutils rpm: error while loading shared libraries: /usr/lib64/liblzma.so.0: invalid ELF header To resolve this issue, the liblzma.so file and associated soft link need to be restored. Follow the steps outlined below … [Read more...] about rpm: error while loading shared libraries: invalid ELF header

Filed Under: CentOS/RHEL 5, CentOS/RHEL 6, CentOS/RHEL 7, Linux

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