LinScsi: SCSILinuxAbortCommands: 1843: Failed, Driver MPT SAS Host, for vmhba2

Issue

Some of the VMs hosted on VMware ESXi 5.5 (DELL PowerEdge T310 host) occasionally become unresponsive.
All attempts to login to the host via VMware vSphere Client fails with following error:

Could Not Connect
vSphere Client could not connect to "10.5.5.25". An unknown connection error occurred. (The request failed because the remote server took too long to respond. (The operation has timed out))

VMware console vmkernel system logs (ALT + F12) display following errors:

mptscsih:  ioc0: task abort: FAILED (sc=0x412e8182ecc0)
WARNING: LinScsi: SCSILinuxAbortCommands: 1843: Failed, Driver MPT SAS Host, for vmhba2
WARMING : ScsiPath: 6292: Set retry timeout for failed TaskMgmt abort for CmdSN   0x0, status
mptscsih:  ¡oc0: attempting task abort! (sc=0x412e81718200)

The vmbha2 refers to a RAID-1 SATA array that had all affected virtual machines hosted.

Installing and enabling PEAR Mail on 1&1 Plesk VPS

PHP PEAR was not installed on my 1&1 VPS (CentOS 7) at all, so the first step was to to install it: 

yum install php-pear

Plesk on CentOS - FTP server (ProFTPd) not working in passive mode

Issue

FTP clients fail to connect to Plesk FTP Server (ProFTPd) hosted on CentOS. FTP login actually succeeds, but directory listing command times out.

Error: Connection timed out after 20 seconds of inactivity.
Error: Failed to retrieve directly listing.

Resolution

The issue occurred because ProFTPd passive mode was not configured on the server.

Backup MySQL database using cron and php

Here is a little PHP script that I use to backup MySQL databases on Hostgator Linux web servers. Simply save the .php file to a non publicly accessible part of the server and run regularly using crontab:

/usr/bin/php /home4/username/my-backups/site-name/backup-task.php

 
<?php
$DATABASE="db_name";
$DBUSER="db_user";
$DBPASSWD="db_password";
$PATH="/home4/username/my-backups/site-name/";
$FILE_NAME="site-name-backup-" . date("Y-m-d") . ".sql.gz";
exec('/usr/bin/mysqldump -u '.$DBUSER.' -p'.$DBPASSWD.' '.$DATABASE.' | gzip --best > '.$PATH.$FILE_NAME);
echo "Database(".$DATABASE.") backup completed. File name: ".$FILE_NAME;
?>