Level | Disks | Hot spare | Available space | Fault tolerance | Read | Write |
---|---|---|---|---|---|---|
RAID 0 | from 2 | - | disk size * dIsk count | - | high | high |
RAID 1 | 2 | + | disk size | 1 disk | medium | medium |
RAID 1E | 2 | - | disk size | 1 disk | high | medium |
RAID 5 | from 3 | + | disk size*(disk count-1) | 1 disk | high | low |
RAID 5EE | from 4 | - | disk size*(disk count-2) | 1 disk | high | low |
RAID 6 | from 4 | + | disk size*(disk count-2) | 2 disk | medium | low |
RAID 10 (1+0) | from 4, even | + | disk size*(disk count/2) | 1 disk in every RAID 1 | medium | medium |
RAID 50 (5+0) | from 6, even | + | disk size*(disk count-2) | 1 disk in every RAID 5 | high | low |
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# Getopts - parsing arguments | |
while getopts "hs:c:" opt; do | |
case $opt in | |
c) | |
echo "Argument $opt at position $OPTIND equals $OPTARG" | |
;; | |
s) | |
echo "Argument $opt at position $OPTIND equals $OPTARG" | |
;; | |
h) |
Type | Tools |
---|---|
RDBMS | MySQL, Oracle Database, IBM DB2, PostgreSQL, Firebird |
NoSQL | MongoDB, CouchDB, CouchBase, Cassandra, HBase, Redis, Riak, Neo4J |
Load Balancing | Nginx, HAProxy |
Web Servers | Nginx, Apache HTTP Server, Lighttpd, Apache Tomcat |
Cluster Infrastructure | Keepalived, Heartbeat, Corosync, Pacemaker, IPVS |
Version control | GitHub, BitBucket, GitLab |
CI/CD | Jenkins, Bamboo, GitLab CI, TeamCity |
Build Tools | Gradle, CMake |
Character | Definition |
---|---|
$* | Expands to the positional parameters, starting from one. When the expansion occurs within double quotes, it expands to a single word with the value of each parameter separated by the first character of the IFS special variable. |
$@ | Expands to the positional parameters, starting from one. When the expansion occurs within double quotes, each parameter expands to a separate word. |
$# | Expands to the number of positional parameters in decimal. |
$? | Expands to the exit status of the most recently executed foreground pipeline. |
$- | A hyphen expands to the current option flags as specified upon invocation, by the set built-in command, or those set by the shell itself (such as the -i). |
$$ | Expands to the process ID of the shell. |
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--- | |
- name: Install Web | |
hosts: hostgroup | |
become: true | |
vars: | |
- repo: | |
Debian: | |
- apt | |
RedHat: | |
- epel-release |
VCS uses two components, LLT and GAB, to share data over the private networks among systems. These components provide the performance and reliability required by VCS.
Name | Description |
---|---|
LLT | LLT (Low Latency Transport) provides fast, kernel-to-kernel comms and monitors network connections. The system admin configures the LLT by creating a configuration file (llttab) that describes the systems in the cluster and private network links among them. The LLT runs in layer 2 of the network stack. |
GAB | GAB (Group membership and Atomic Broadcast) provides the global message order required to maintain a synchronised state among the systems, and monitors disk comms such as that required by the VCS heartbeat utility. The system admin configures GAB driver by creating a configuration file ( gabtab). |
Name | Description |
---|---|
vxconfigd It can be in three states: Enable = Normal mode Disable = Most operations cannot be be used Booted = Normal startup while using boot disk group |
Maintains system configuration in the kernel & disk (private region).If the daemon is stopped it does not disable any configuration state loaded into the kernel, it only affects the ability to make configuration changes until vxconfigd is restarted. |
vxrelocd | Monitors for failure events and relocates failed subdisks |
vxconfigbackupd | Used to backup configuration chnages, the files created can be used with vxmake to restored lost groups. |
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