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
Archives for December 2019
MySQL Table Maintenance – InnoDB, MyISAM, MEMORY, ARCHIVE
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
Understanding mysqlcheck and myisamchk utilities
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
CentOS/RHEL – How to Remove stale ISCSI Target Node Information from ISCSI Initiator Server
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
CentOS/RHEL 6 Kernel Panic – “Out of memory” kernel parameter panic_on_oom is enabled
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
How to enable core dump for Applications on CentOS/RHEL
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