wordpress DB connection error

[skyxing]

Hello, I am a novice of Sentora.

Too frequently I encountered the message "DB connection error"
I can't find method for fixing this severe problems...

I had to resolve temporary this problems by rebooting VPS, but... feel so bad... ^_^;;;;;
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I started Sentora on VPS(ubuntu 14.04 + PHP + mysql), and using several wordpress sites(not multisite, just several independent domains).

The detailed system configuration is as follows.


### WordPress Environment ###

Home URL: http://xweb.kr
Site URL: http://xweb.kr
WP Version: 4.2.2
WP Multisite: –
WP Memory Limit: 128 MBYour current memory limit is sufficient
but if you need to import classic demo content
the required memory limit is 256MB.

WP Debug Mode: –
Language: ko_KR

### Server Environment ###

Server Info: Apache
PHP Version: 5.5.9-1ubuntu4.9
PHP Post Max Size: 100 MB
PHP Time Limit: 300
PHP Max Input Vars: 6000 - Recommended Value: 9000.Max input vars limitation will truncate POST data such as menus. See: Increasing max input vars limit.
SUHOSIN Installed:
Suhosin Post Max Vars: 6000 - Recommended Value: 9000.Max input vars limitation will truncate POST data such as menus. See: Increasing max input vars limit.
Suhosin Request Max Vars: 6000 - Recommended Value: 9000.Max input vars limitation will truncate POST data such as menus. See: Increasing max input vars limit.
ZipArchive:
MySQL Version: 5.5.43
Max Upload Size: 100 MB
Default Timezone is UTC:

### Active Plugins (6) ###

Duplicator: by LifeInTheGrid – 0.5.22
Fusion Core: by ThemeFusion – 1.7.3
Jetpack by WordPress.com: by Automattic – 3.5.3
WordPress SEO: by Team Yoast – 2.1.1
WordPress Social Stream: by Lee Chestnutt – 1.5.12
WP Super Cache: by Automattic – 1.4.4