Month: May 2019

HA(high availability)

HA refers to high availability, and to minimize the frequency and time that functions and services provided by the system are stopped or interrupted. Also, a system (HA) or a system configuration(HA configuration) in which such measures are taken may be simply referred to as HA.
In a narrow sense, multiple computers are bundled and operated in an integrated manner, and clustering technology that makes them behave as if they are one computer prevents the whole from stopping even if one stops. It refers to the state(HA cluster).

In a broad sense, it includes all techniques such as redundancy and multiplexing (duplexing) of equipment and systems, data replication and automatic switching, and a hot standby configuration and cold standby configuration in which two systems of the same system are prepared in some cases, HA may be promoted using database replication and the like (and their combination).

RGL

RGL is a package in which functions for performing three-dimensional plotting are condensed. Three-dimensional plots can be created, and the plotted figures can be moved with the mouse, and enlargement / reduction can be performed.

Here is an example of the instructions from installing the package to displaying example. After plotting, you can rotate the figure by moving the mouse while holding the figure with the left click, or zoom in and out of the figure by turning the mouse wheel.

install.packages("rgl")
library(rgl)
open3d()
example(rgl.surface)
for(i in 1:360) rgl.viewpoint(i, 1/4)

Holacracy

The term “holacracy” refers to social technology or organizational governance management to maintain a self-propelled organization by distributing authority and making decisions throughout the organization rather than making decisions through traditional top-down hierarchies. It is defined as the method.

LWP::Protocol::https

my $url = "https://xxx.yyy.jp";
my $request = HTTP::Request->new(GET => $url);
my $ua = LWP::UserAgent->new;
my $res = $ua->request($request);
my $resutl = $res->content;

There is no problem with HTTP pages, but it fails with HTTPS.

cpan istall LWP::Protocol::https

Cpanm Crypt::SSLeay

openssl-devel

Files needed to develop applications that use OpenSSL

OpenSSL is a toolkit to support cryptography. The openssl-devel package contains the static libraries and header files needed to develop applications that support various encryption algorithms and protocols.

yum list installed | grep ${package}

yum update “software”
→　update software

yum remove “software”
-> Uninstall software

yum list installed
-> display a list of already installed

yum list installed | grep “software name”
-> display the version name of the specified software

yum list
-> display a list of installable software

yum list updates
-> this is a list of installed software that requires update

[vagrant@localhost ~]$ yum list installed
読み込んだプラグイン:fastestmirror
Repository nodesource is listed more than once in the configuration
Repository nodesource-source is listed more than once in the configuration
Loading mirror speeds from cached hostfile
* base: ty1.mirror.newmediaexpress.com
* extras: ty1.mirror.newmediaexpress.com
* remi-safe: ftp.riken.jp
* updates: ty1.mirror.newmediaexpress.com

[vagrant@localhost ~]$ rpm -qa | grep openssl
openssl-devel-1.0.1e-57.el6.x86_64
openssl-1.0.1e-57.el6.x86_64

[vagrant@localhost ~]$ yum list installed | grep openssl
openssl.x86_64 1.0.1e-57.el6 @base
openssl-devel.x86_64 1.0.1e-57.el6 @base

Net-Amazon-S3-0.86

Net::Amazon::S3 – Use the Amazon S3 – Simple Storage Service
Version 0.86

This module provides a Perlish interface to Amazon S3. From the developer blurb: “Amazon S3 is storage for Internet. It is designed to make web-scale computing easier for developers. Amazon S3 provides a simple web service interface that can be used to store and retrieve any amount of data, at any time, from anywhere on the web. It gives any developer access to the same highly scalable, reliable, fast, inexpensive data storage infrastructure that Amazon uses to run its own global network of web sites. The service aims to maximize benefits of scale and to pass those benefits on to developers”

use Net::Amazon::S3;
my $aws_access_key = 'fill me in';
my $aws_screte_access_key = 'fill me in too';

my $s3 = Net::Amazon::S3->new(
{
	aws_access_key_id => $aws_access_key_id,
	aws_secret_access_key => $aws_secret_access_key,
	use_iam_role => 1,
	retry => 1
}
);

my $response = $s3->buckets;
my $bucket( @{ $response->{buckets}})
	or die $s3->err . ": " . $s3->errstr;

$bucket = $s3->bucket($bucketname);

$bucket->add_key_filename('1.JPG', 'DSC06256.JPG',
	{ content_type => 'image/jpeg',},
) or die $s3->err . ": " . $s3->errstr;

5G

Currently, the 4th generation LTE is the mainstream, but if 5G is realized, it will be possible to transmit about 10 times faster than LTE. In addtion, devices that can be connected simultaneously are 100 times faster than LTE, and the delay is about 1/10 of LTE.

5G is linked with new radio technology “5G NR(New Radio)” and advanced LTE to form a network, and can handle a wide frequency band.

With the spread of AI, IoT, etc., communication traffic is expected to increase further in the future, and it is expected that the realization of 5G will cope with the increased amount of information.

centOS iptables and firewalld

firewalld can not be used with iptables.
By default, firewalld is enabled, so disabled firewalld if using iptables, you must install iptables-service and enable iptables.

If you want to configure easily to work with external services with api, firewalld.

If you want to configure easy + to work with external service with api, firewalld.

If you want to do complex things, it is better to use iptables.

[vagrant@localhost ~]$ cat /etc/redhat-release
CentOS release 6.10 (Final)

[vagrant@localhost ~]$ sudo /etc/rc.d/init.d/iptables status
iptables: ファイアウォールが稼働していません。

Linux command systemctl

NAME
       systemctl - Control the systemd system and service manager

SYNOPSIS
       systemctl [OPTIONS...] COMMAND [NAME...]

DESCRIPTION
       systemctl may be used to introspect and control the state of the "systemd" system and service manager. Please refer to systemd(1) for an introduction into the basic concepts
       and functionality this tool manages.

service start: systemctl start ${unit}
service stop: systemctl stop ${unit}
service restart: systemctl restart ${unit}
service reload: systemctl reload ${unit}
service status display: systemctl status ${unit}
service auto start: systemctl enable ${unit}
reject service auto start: sytemctl disable ${unit}
confirm service auto start: system is-enabled ${unit}
service list display: system list-unit-files –type=service
reload setting file: systemctl daemon-reload

[vagrant@localhost ~]$ ls /etc/init.d/
auditd iptables messagebus ntpdate rsyslog
blk-availability jenkins mysqld postfix sandbox
crond kdump netconsole rdisc saslauthd
elasticsearch kibana netfs rdma single
functions killall network restorecond sshd
halt lsyncd nfs rpcbind udev-post
htcacheclean lvm2-lvmetad nfs-rdma rpcgssd vboxadd
httpd lvm2-monitor nfslock rpcidmapd vboxadd-service
ip6tables mdmonitor ntpd rpcsvcgssd vboxadd-x11

[vagrant@localhost ~]$ sudo /etc/init.d/elasticsearch
使い方: /etc/init.d/elasticsearch {start|stop|status|restart|condrestart|try-restart|reload|force-reload}

[vagrant@localhost ~]$ sudo /etc/init.d/elasticsearch start
elasticsearch を起動中: OpenJDK 64-Bit Server VM warning: Option UseConcMarkSweepGC was deprecated in version 9.0 and will likely be removed in a future release.
OpenJDK 64-Bit Server VM warning: INFO: os::commit_memory(0x00000000e5f30000, 437059584, 0) failed; error=’Not enough space’ (errno=12)
#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (mmap) failed to map 437059584 bytes for committing reserved memory.
# An error report file with more information is saved as:
# /var/log/elasticsearch/hs_err_pid10362.log
[失敗]