Category:

Operating Systems

How to install PHP latest version

by mn.sobieh January 9, 2021

Installing PHP can be either from Debian default repository which is stable but is not upto date or from the sury.org repositoy which provide the latest packages compatiable with debian and Ubuntu.

This article shows the steps to create an APT source list file that allows you to the latest version of PHP repository for Debian and Ubuntutu.

What is SURY?

SURY repository contains many packages, however, PHP is what it is famous for. more details on their website

Steps to Create a repository for PHP

The following step will do the following

First, install a few tools required

Next, add the repository key to Trusted keys.

Then, Create the repository source list.

sudo apt-get install curl apt-transport-https

sudo wget -O /etc/apt/trusted.gpg.d/php.gpg https://packages.sury.org/php/apt.gpg

sudo echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" > /etc/apt/sources.list.d/php.list

Install PHP packages

to facilitate the installation process. I create a variable pv to hold the version you want it could be 7.0, 7.1, 7.2,7.3, 7.4 or 8.0

pv="7.0"
#Core liberrary
apt-get install -y php$pv php$pv-common php$pv-zip php$pv-fpm php$pv-curl
#structure support XML, JSON, Yaml
apt-get install -y php$pv-yaml php$pv-json php$pv-xml php$pv-xmlrpc 
apt-get install -y php$pv-cli php$pv-gd php$pv-intl php$pv-tidy  php$pv-xsl
#Encryption and ldap authentication
apt-get install -y php$pv-ldap php$pv-mcrypt 
#performance enhancement 
apt-get install -y php$pv-mbstring php$pv-bcmath php$pv-readline
#caching
apt-get install -y php$pv-memcache php$pv-memcached   
# database modules
apt-get install -y php$pv-mysql php$pv-redis

Finally, Check if the FPM service is active by typing.

systemctl status php$pv-fpm

How to free oracle disk space – Automate disk cleanup.

by mn.sobieh August 21, 2020

In part one we explained what files Oracle Instance creates and eats our precious disk-space, This article explains how to identify and free oracle server disk space.

Reasons for the server to stop creating new files.

Servers might stop creating new files or adding new files due to multiple reasons:

1. You consumed all available disk space.

in that error, you get the message.

oracle@srv$ touch textfile 
touch: cannot touch ‘textfile’: No space left on device

You can detect file system disk space usage by executing the du command with -h parameter.

2. Your disk quota reached its limit.

oracle@srv$ mkdir tstdir
mkdir: cannot create directory ‘tstdir’: Disk quota exceeded

3. You consumed all allowed Inodes.

An inode is a data structure used to keep information about a file on your hosting account. The number of inodes indicates the number of files and folders you have. This includes everything on your account, emails, files, folders, anything you store on the server.

using du command with parameter -i it will show total nodes used and available Inodes for each mounted disk.

oracle@srv$ du -i

What directories need cleaning?

in that clustered environment which consists of two nodes and ASM. The script cleans the following directories

ASM Audit trail.
in ASM home “create separate ” script to be executed by grid user

/u01/app/12.1.0/grid/rdbms/audit

Database Audit trails.
in Database home

$ORACLE_BASE/diag/rdbms/$ORACLE_SID/$ORACLE_SID/trace

Database trace files.
in Database home

$ORACLE_BASE/admin/$ORACLE_SID/adump

ADRCI to clean your Oracle disk-space

After identifying the biggest directories that consume your server disk space. you need three environment variables which are ORACLE_UNIQNAME, ORACLE_SID, ORACLE_BASE

export ORACLE_UNQNAME=cdb1 
export ORACLE_SID=cdb1 
export ORACLE_BASE=/u01/app/oracle

Clear Audit and trace files using the Automatic Diagnostic Repository (ADR) tool. adrci located in bin under oracle home.

/u01/app/oracle/product/12.1.0/dbhome_1/bin/adrci

Next, list available homes that have logs.

adrci> show homes
ADR Homes:
diag/rdbms/omandb/omandb
diag/rdbms/tst/tst
diag/rdbms/db12c/db12c
diag/rdbms/cdb1/cdb1
diag/rdbms/dbks/dbks
diag/tnslsnr/ora12c/listener
diag/clients/user_oracle/host_1954257820_82

Then, set adrci home that the purge command will work in. for example, for cdb1

set home diag/rdbms/cdb1/cdb1

After that, purge all logs.

adrci> purge -age 60

Finally, repeat this process with each home. in addition, if there are other oracle software installed change the adrci base, then repeat the same process.

Schedule cleaning script.

First, create a cleanup script and put in it the command that will remove all traces and audit files.
oracle@srv$ vi /u01/cleanUP.sh

export ORACLE_UNQNAME=cdb1 
export ORACLE_SID=cdb1 
export ORACLE_BASE=/u01/app/oracle 
find $ORACLE_BASE/admin/$ORACLE_SID/adump -name “*.aud” -mtime +14 -type f -delete 
find $ORACLE_BASE/diag/rdbms/$ORACLE_SID/$ORACLE_SID/trace -name “*.tr?” -mtime +14 -type f -delete

now you add it to cron scheduler to execute every day at 1AM. Read corn manual for more information

oracle@srv$ crontab -e 

00 01 * * * find /u01/cleanUP.sh

To conclude,

Linux Operating Systems Oracle

How to free oracle server disk space.

by mn.sobieh August 19, 2020

Oracle database creates various types of files for logging each has its role. For example, Trails, trace files, and logs. These files are important and provide a lot of information, it will quickly consume server space handicapping server performance. That if they were not maintained properly. This article goes through the process of finding what eats Server space and provides a clear explanation of free oracle server disk space.

While I was monitoring Oracle 12c cluster for one of the clients, I noticed a fast decline in oracle server free disk space, and Oracle home is creating lots of log files, trace files, and Audit files.

If DBA neglect regular maintenance, the Oracle home directory can grow very large, as, the number of audit trail, logs, and trace files fills up the server’s disk-space, even if the system os online for less than a few months.

What eats my server’s space?

first, you need to investigate from which folder causing the problem by estimate file space usage for each folder by executing the du command

du -sh  ./* | sort -h

-s display only a total for each argument

-h print sizes in human-readable format (e.g., 1K 234M 2G)

sort the output by size.

It is better to start digging from your oracle home, then identify which directory is eating your server disk-space. Next, navigate into that folder and repeat the procedure until you identify all folders that consume most of the free space (I call it the naughty list).

du -sh ./* | sort -h

Locations and Types of log files

#Oracle_database creates many types of files and does not track them. hence, in long run these files trouble. Usually, these files are related to Instance operation, security, backups, memory, instance errors, and others. in addition, these files stored in local file system.

Audit trail files

Oracle Database provides robust audit support in both the Enterprise and Standard Edition of the database. furthermore, the Audit records include information about the operation ,like , the user performing the operation, and the date and time of the operation. Audit records stored in the database audit trail or in files on the operating system. Standard auditing includes operations on privileges, schemas, objects, and statements.

You can configure Audit location by modifying database parameters.

AUDIT_FILE_DEST

specifies the operating system directory into which the audit trail is written when the AUDIT_TRAIL initialization parameter is set

AUDIT_SYS_OPERATIONS.

Enables the auditing of operations issued by user SYS, and users connecting with SYSDBA, SYSOPER, SYSASM, SYSBACKUP, SYSKM and SYSDG privileges. The audit trail data writs to the operating system audit trail.set This parameter value to true.

The default location of the operating system audit trail on Unix/Linux is $ORACLE_BASE/admin/$ORACLE_SID/adump. The default on Windows is the event log.

For optimal performance, it should refer to a directory on Oracle server local disk.

Trace Files

Trace File is a text file ( called dump) that Oracle Database creates to help you diagnose and resolve operating problems. Each server and background process writes to a trace file. When a process detects an internal error, it writes information about the error to its trace file.

the Automatic Diagnostic Repository (#ADR) stores Trace files in the trace directory under each ADR home. To help you locate individual trace files within this directory, you can use data dictionary views. For example, you can find the path to your current session’s trace file or to the trace file for each Oracle Database process.

To find all trace files for the current instance:

SELECT VALUE FROM V$DIAG_INFO WHERE NAME = 'Diag Trace';

The output is the ADR trace directory path for the current instance. To control the number of these files, and manage it with operating system tools:

Part two will explain how to free oracle disk space automatically using cleanup scripts and oracle commands.

Linux Operating Systems

Linux Software Management – Yum basics

by mn.sobieh August 17, 2020

Since Software management is an essential part of operating system management, for that, this article explains yum basics and the common command and options, as this package manager allows install, update, remove, or search for packages.

Common Linux distributions come with its package manager, for instance, Debian and Ubuntu use APT. on the other hand, Redhat, CentOS, OEL, and Fedora provide Yum and DNF as their package manager.

Yum vs DNF

DNF is the new major upgrade of Yum, It’s short for Dandified YUM and It became the default Package manager in Fedora, CentOS 8, RHEL 8. besides all features DNF brings to the os, It has the same syntax as yum.

The main syntax as described in this pic : yum [options] [command] [package …]

To utilize Linux package managers, like yum or DNF. you should be a privileged account “root”.

Yum Commands

Though, man provide rich documentation for yum, it has too much information that confuses the reader. for that, This article will focus on the most used one

Package management

The following yum command used to manipulate packages.

search	Search package details for the given string.
list	List a package or group of packages. for example: yum list htop
install	Install a package or packages on your system.
update	Update a package or packages on your system.
erase	Remove a package or group of packages from your system.

DNF repository management.

repolist

Display the configured software repositories. also, you can append the following option to control its output:
all –> show all repositories in the systems.
disabled –> show only disabled repositories.
enabled –> show only enabled repositories it, it’s same as using repolist without any options.

Yum Maintenace & troubleshooting

check	Check for problems in the rpmdb.
clean	Remove cached data and free space. You need to append one of the following values to the command: All cache dbcache expire-cache headers metadata packages
check-update	Check for available package updates.

Options for YUM or DNF.

-4	Resolve to IPv4 addresses only. besides, you can use -6 to resolve using IPv4 addresses.
–disablerepo=<repoid>	Disable specific repositories by an id or a name. also, This option is mutually exclusive with –repo.
–downloadonly	Download the resolved package without performing any rpm transaction, for example, install, upgrade, or erase package.
–enablerepo=<repoid>	Enable additional repositories by an id or a global name. besides the currently available packages.
–allowerasing	Allow erasing of installed packages to resolve dependencies.
-b, –best	Try the best available package versions, Specifically, during dnf upgrade operation.
–enhancement	Include packages that will improve the main package features. Applicable for the install, repoquery updateinfo, and upgrade commands.
-y, –assumeyes	Automatically answer yes for all questions.

DNF autocomplete

if you want to enable autocomplete for yum and DNF, Install python and bash-auto complete packages.

sudo dnf  -y install python 
sudo yum -y install bash-completion bash-completion-extras

To conclude, These were the most used options and commands for yum command. however, it has many other features this article does not cover.

Change-WSUS-update-storage-00-FeaturedImages

Windows

Change WSUS Contents location

by mn.sobieh August 15, 2020

Have you tried to move WSUS contents folder to another location and failed, or can’t move WSUS content due to permission issues. This article explains how to use wsusutil to change WSUS content location.

WSUS Tool location.

Changing the WSUS update folder is not a CUT& PAST operation. to explain, There is a lot of work that includes updating registry values, database records, IIS configuration, and much stuff. Instead, Microsoft provides a utility to do all that, and it comes with Windows Server Update Services installation. The tool is wsusutil.exe

if you moved the WSUS storage manually using xcopy command, you still need to run WSUSutil.exe to update the WSUS.

Its location varies according to which Windows version you are using. for example, in Microsoft documentation, it says WSUSInstallationDrive:Program Files\Microsoft Windows Server Update Services\Tools. however, in windows 2016 default location is C:\Program Files\Update Services\Tools.

Why Change WSUS update storage fails

If are getting an error message like the ” Fatal Error: Unable to access the log path because of the following error: Access to the path is denied.”. it’s because either you do not have required privileges or command syntax was wrong.

You must be a member of the local Administrators group on the WSUS server.
The destination folder where update files are moved to must be on an NTFS partition.

WSUS wsusutil tool, One tool to do it all.

This tool comes with many options. It allows you to change the WSUS content folder, Purges the unnecessary updates, troubleshooting.

wsusutil movecontent

to change WSUS content data we will use the movecontent command of WSUSutil.exe, in our example, we will move the WSUS folder from D:\WSUS1 to E:\WSUS.

First, log into the WSUS server.

Then, create a new path for local WSUS update storage.

Next, to change the location of local WSUS update storage complete the following steps:

1. Click Start, and then type CMD.
2. Right-click on Command Prompt and choose Run as administrator.
3. At the command prompt, navigate to the directory that contains WSUSutil.exe.

cd C:\Program Files\Update Services\Tools

4. Type the following, and then press ENTER:

wsusutil.exe movecontent E:\WSUS E:\wsus-relocation-task.log

wsusutil Syntax:

You need to give the tool the new location of the WSUS update folder and filename to log the process output, besides if you only want to change the location of local WSUS update storage without copying any files. You can use -skipcopy parameter at the end of the command

wsusutil.exe movecontent NewLocationPath logFilePath [-skipcopy]

In conclusion, Microsoft provides wsusutil tool to facilitate WSUS management and troubleshooting. with one command you can maintain WSUS update storage.

Ansible Windows

Enable remote powershell for Windows

by mn.sobieh August 9, 2020

PowerShell is a framework from Microsoft. it’s heavily used in scripting and task automation. that is to say, PowerShell allows administrators to perform tasks on both local and remote Windows systems as well. hence, This topic aims to enable remote PowerShell execution for Windows by configuring winRM.

Check how to configure Ansible to manage windows.

Keep in mind that Ansible require

Ansible supports Windows 2008 and above. Though, configuration for versions earlier than Windows 2008 R2 is troublesome. for that, upgrade to at least win2008R2.
Ansible requires PowerShell version 3.0 and .NET Framework 4.0 or newer to function because most Ansible modules for windows require at least PowerShell 3.0 or higher to work properly, and Windows 2008 R2 has version 3.0.
A WinRM listener should be created and activated.
You need a centralized Windows privileged user (Administrator@Domain ) if you are going to manage multiple windows servers. It’s a hassle if every server has its distinct username or password.

Configure Windows to accept remote commands

If you have to use older versions of windows please refer to Ansible document to scripts which will allow you to upgrade your PowerShell.

On Windows hosts, you need to enable the Remote Management feature which is a built-in feature but it’s not active by default. Windows Remote Management (WinRM) is the Microsoft implementation of the WS-Management protocol which provides a secure way to communicate with local and remote computers using web services.

You have two easy ways to enable WinRM

One: Enable winRM using Ansible team’s script.

Ansible team provides a script that will configure WinRM. So, to execute that script, follow these steps.

First, Download Ansible PowerShell documentation script from here “Right click and save as ConfigureRemotingForAnsible.ps1”.

Then, allow running unsigned scripts on your local computer and signed scripts from remote, by executing the following command.

set-executionpolicy remotesigned

Next, open a PowerShell as Administrator console

Finally, execute the downloaded script ConfigureRemotingForAnsible.ps1 . the output should be like the following screenshot

Two: use SolarWinds Remote Execution Enabler for PowerShell tool.

That tool is a free desktop app that will configure WinRM on local and remote servers In just one step, in addition, It can do bulk configuration across multiple hosts, also, it will automatically generate and distributes certificates for encrypted remote PowerShell execution.

First, download it from the SolarWinds website. As the installation is simple, then, in a few clicks and finish the installation.

Next, Execute the application from the start menu.

Finally, configure the server, by following these steps:

Enter Server IP
Enter Administrator’s Password.
Click on Start Configuration

Linux Operating Systems

list open ports using netstat

by mn.sobieh August 7, 2020

netstat is an essential tool for network issues diagnoses. for example, It prints OS network connections and list open ports, routing tables, interface statistics, masquerade connections. netstat comes in most Operating systems like Windows and Linux. however, in recent Linux releases it was superseded by other commands like ss and “IP” commands. Though, to unlock its full potentials, you have to use its parameter. in this article explain

netstat parameters

Admins usually use netstat to check specific things. therefore, they use its parameters to achieve that. however, if you execute netstat command without any parameters, it will print all active connections. keep in mind that ss command has replaced netstat without any parameter.

You can get all available parameters by typing –help or visit netstat manual, Instead, I will talk about the useful combination of parameters that comes with netstat. for that, the following table show number of parameter:

–listening	-l	listen
–numeric	-n	numbers instead hostnames and service description
–program	-p	list program connecting on that port
–tcp	-t	TCP ports only
–udp	-u	UDP ports only
–version	-V	show netstat version
–route	-r	list routing table, the command ip route replaces it

netstat list open ports on Linux.

To print Active ports that are listening to connections, in addition to the application responsible for opening the ports and their PID.

# netstat -lnp

Bellow, The output in order, the protocol, Recv-q, Send-Q, the Local listening port & Address, connected foreign port & address, the state of the port, and finally Process ID and Program name.

netstat-lnp output

besides, You pipe netstat output into other commands like grep, egrep, or awk to filter the output. and search for a specific port or application.

to view information about a specific open port:

# netstat -lnp | grep ":<port number>"

The view information about a specific application and list the ports related to it.

# netstat -lnp | grep "<application Name>"

scan open ports using nmap tool.

Nmap is a port security network scanner. hence, it helps you to check servers’ firewall settings and security configurations. For example, to scan for open ports for specific server IP and list open ports

nmap –p– <Server IP>

To conclude, many applications open ports to communicate with remote resources. hence, to list the applications that are opening ports and listening for remote requests. For that, we used netstat that comes with Linux and windows to list the ports.

disable-NetworkManager-in-OEL7-and-manually-configure-Ethernet -featuredImage

Linux Operating Systems

manually configure network in OEL 7, CentOS 7

by mn.sobieh August 5, 2020

When you install CentOS, RHEL, or OEL with graphical Interface, it comes with NetworkManager. The NetworkManager daemon maks networking configuration and operation easy and automatic as possible by managing network interfaces, either Ethernet, WiFi, or Mobile Broadband devices. Besides, NetworkManager provides a rich API to control network settings and operations. However, when configuring servers It’s preferable to have their networking settings to be consistent. therefore, This article explains how to disable NetworkManager, hence, configure the network and set IP ethernet manually.

The following steps are suitable for versions 6 and 7 of RHEL, OEL, and CentOS.

Firstly, Identify which card you want to configure by executing the ifconfig command with parameter -s to shortlist the output.

[root@s59 ~]# ifconfig -s
Iface    MTU    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg 
eno1     1500  4596894    0   5617 0        41057    0      0      0 BMRU 
lo       65536     440    0      0 0        440      0      0      0 LRU 
virbr0   1500        0    0      0 0          0      0      0      0 BMU 
[root@s59 ~]#

In view of the output of our example, you can see that the server has three network interfaces, as follow:

eno1	LAN Network interface
lo	Loopback interface
virbr0	Wireless Network interface

In our case, LAN Interface eno1 is our target.

Disable NetworkManager

Firstly, Stop NetworkManager by stopping its service.

systemctl stop NetworkManager.service

Secondly, disable Network Manager using the following command.

systemctl disable NetworkManager.service

manually configure network setting.

Initially, navigate into the network configuration directory. then, edit the configuration file for the ethernet. For example, if the card name eno1 then the filename is ifcfg-eno1.

vi / etc/sysconfig/network-scripts/ifcfg-eno1

After that, add the following parameters in the file if they are not exist

ONBOOT=yes 
NM_CONTROLLED=no 
BOOTPROTO=none 
IPADDR=XXX.XXX.XXX.XXX
NETMASK=255.255.255.0
# you can use PREFIX=24 instead of NETMASK=255.255.255.0
GATEWAY=<GATE WAY IP XXX.XXX.XXX.XXX>

manually configure network in OEL 7, CentOS 7 - ifcfg-eno1

Optional you can add the following lines to force DNS on specific Card

 DNS1=<DNS IP XXX.XXX.XXX.XXX>                
 DNS2=<DNS IP XXX.XXX.XXX.XXX>

Manually configure DNS resolve file.

make sure it has a reliable DNS IPs, for example, google public DNS 8.8.8.8

 vi /etc/resolv.conf  
 nameserver 8.8.8.8

manually configure network in OEL 7, CentOS 7 - resolv

Finally, type :wq to save & exit the editor.

Restart network services

For version 6, use the service command.

# Service restart network

On RHEL 7 use systemD command, though, executing the above command will redirect to systemD command

# systemctl restart network.service

Windows

setup IIS reverse proxy

by mn.sobieh August 3, 2020

A proxy server acts as an intermediary for requests from clients seeking resources from servers that provide those resources, In other words, The proxy controls and filters the data that go through it. Hence, organizations use it to filter and control Internet access, or to protect their servers. This article explains how to setup IIS reverse proxy using Application Request Routing ARR addons, So you can protect your servers.

This article is part of a series, how to manage, and troubleshoot the Microsoft IIS server.

Install IIS on Windows Server.
Configure a reverse proxy.
Setup IIS SSL certificate.
troubleshoot IIS reverse proxy error 500.25.
troubleshoot IIS reverse proxy ERR_CONNECTION_RESET.

Why would I setup a reverse proxy?

Proxy servers provide varying levels of functionality, for example, security to achieve load balancing and high availability. For example, a website may have several web servers behind the reverse proxy for high availability. Above all, It depends on your use-case, needs, or company’s policy.

How to configure a reverse proxy server on IIS server?

Easy two steps to enable reverse proxy in IIS.

Install IIS extension.

URL rewrite extension: Download the extension from here. Or google it.
Application Request Routing (ARR) extension from here. Or google it.

Create an inbound rule

Allow redirection of any request coming to proxy to your Internal server.

Proxy Inbound

Create outbound rule (Optional)

Allow you to control outbound transactions based on conditions redirection of any transaction coming from the server to the client to be masked with a specific URL.

Proxy outbound

Full example, step by step Setup IIS reverse proxy.

In this example we prepare two servers, the internal web server uses Ubuntu and the second server will act as a proxy server. As shown in the following table

	Reverse Proxy	WebServer
Operating System	Windows	Linux
IP Address	192.168.160	192.168.157.180
port	80	80
protocol	HTTP	HTTP
Server Name	prxy	Srv

Server names should be added to the client hosts file

Configure Internal server Installing Apache webserver

Easy steps just install apache webserver using the following command

 sudo apt-get install apache2 -y

Then , check if the apache installed the default index.html page. by executing the following command.

ls /var/www/html/index.html

Also, test your installation by opening your browser. then, type Ubuntu server IP to test if the webserver is runing. You should see a page like that

ubuntu-index

Configure IIS Proxy Server

Firstly, Open the IIS Manager. then, on the left side Navigate under “server name”, right-click on “Sites”, then chose Add website. After that, In the new window, enter the website name, location, and Listening Host-name.

Than, On the right side click on URL Rewrite Icon.

Choose Reverse Proxy then click OK. It will ask if you want to enable Proxy functionality, so click OK.

After that, when the Add Reverse Proxy window appears in the upper section titled ” inbound Rules” enter the Internal server hostname or IP of the internal server where HTTP requests will be forwarded to.

Finally, do not check the outbound rules as we will configure it separately, Click OK.

Conclusion

To summarize, with these steps you configured IIS to work as a reverse proxy server. you can test your efforts by typing the IP/URL in the browser.

Linux Operating Systems

xm destroy – restore vanished vms

by mn.sobieh July 29, 2020

this article addresses a common issue that happens when you use xm destroy command. Hence it will show how to solve this issue and restore vanished VMs.

What is XM?

xm command is a program that allows you to manage Xen virtualization guest virtual machines. In other words, This program can list, create, pause, and shutdown VMs. in addition, it controls the machine’s virtual block devices. though it’s very powerful, it does not handle error checking or configuration file errors very well and mistakes can lead to system instability or errors in virtual machines. Therefore, in future you should use virsh or virt-manager commands instead.

I was taking a course one of the tasks is to crash the server which runs the services. I applied the command to crash the VM

Linux XM command explained.

To take any action on XEN based virtual machines using xe command. generally, you need to add a parameter and define your target virtual machine.

xm <options>  <Target>

XM options

`xm list`	List active virtual machines
`xm create [-c] vmName/ID`	Start a virtual machine. If the -c option is used, the start up process will attach to the guest’s console.
`xm consolevmName/ID`	Open a virtual machine’s console
`xm destroy vmName /ID`	Force a virtual machine to power off.
`xm reboot vmName /ID`	Reboot a virtual machine, runs through the normal system shut down and start up process.
`xm shutdown vmName /ID`	Shut down a virtual machine, runs a normal system shut down procedure.
`xm pause`	Pause virtual machine
`xm unpause`	Resume virtual machine
`xm start vmName`	Start powered off virtual machines

problem xm destroy hide VMs, how to solve it ? .

It happens, that when you execute xm start command, it returns an error that there is no machine with that name, apparently, xm destroy hide the VM as if it’s deleted. moreover, When you list the available machines using xm –list. the machine does not show in the list.

The solution is to find where the config files of that VM. then, create a new virtual machine or rather I registered it again by executing

cd /location/of/vmFiles
xm create <virtName.conf>

the result of this command creates a new instance of the virtual machine using its existing configuration files and registers it again. and by that, you will be able to restore that vanished vm

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