How to Configure High Availability Feature in XenServer

Instructions

Complete the following procedure to enable and disable HA on your XenServer pool:

1. To enable HA for your XenServer pool (with three or more hosts), select the Pool Name/Resource Icon:
   
   
2. Right-click the Pool Name/Resource icon and select High Availability...
   
   
3. Alternatively, with the Pool Name/Resource icon highlighted, select the HA tab and select Configure HA…
   
   
4. The Configure HA dialog box appears. Read the requirements before selecting Next.
   
   
5. The configuration wizard scans the pool for a Hearbeat SR. If no suitable SR is found, the wizard will exit and one must establish the High Availability Heartbeat Storage Repository (per requirements).
   
   
6. When an appropriate SR is found, select it and press Next.
   
   
7. The configuration will present all VMs that are currently in the pool. It is from this configuration dialog will allow one or multiple VMs to be selected as to specify:
   
   1. The HA restart priority that defines if VMs should be – with enough resources available in the pool – Restarted, Restarted if Possible, and Do Not Restart
   2. The Restart Order - 0 being the highest - that specifies the priority of a VM (or VMs) to be started under a fail-over condition
   3. The Attempt to start next VM delay that specifies how much time should pass before starting the next priority-based VM (or group of VMs).  This is to ensure pool resources are not overwhelmed when recovering from a fail-over condition

8. When the HA conditions are specified, selecting Next presents a review of the HA config. Pressing Finish confirms the configuration and apply it to the pool.
   
   
9. With the successful application of the HA configuration across the pool, the HA tab should show the following:
   
   
10. To begin the process of disabling HA for your XenServer pool (with three or more hosts), select the Pool Name/Resource icon:
    
    
11. With the Pool Name/Resource icon highlighted, select the HA tab and select Disable HA…
    
    
12. When prompted to disable HA, select YES.
    
    
    
    The HA is disabled across the pool (for each member).

How to set up management access for the N4000 switch

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Table of Contents

1.    Setting a management IP address

2.    Setting Login access on the switch

3.    Choosing Telnet, HTTP, SSH, or HTTPS for management

4.    Saving configuration

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Article description: This article explains how to set up different management options for the N series switches, and explains the recommended settings

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Setting a management IP address

A reachable IP address is needed to manage the switch when not using a serial connection. To set an IP address, input the following commands.

This example uses VLAN 1, the default VLAN, and the IP 192.168.0.250 /24.

console>enable

console#configure

console(config)#interface vlan 1

console(config-if)#ip address 192.168.0.250 255.255.255.0

Note: On the N3000 and N4000 switches there is an out of band port that can be used for managing the switch.

Here is the same example but using the out-of-band (OOB) interface.

console(config)#interface out-of-band

console(config-if)#ip address 192.168.0.250 255.255.255.0

It is recommended to use the OOB interface to manage your switch when available. The OOB interface is separate from the switching silicon,

and reaches the CPU directly. If the production network is experiencing issues, you can still reach the switch through the OOB interface.

Note: Plug the OOB interface into a separate management network, and do not plug it back into the inbound ports on the switch.

It is recommended when using a VLAN to manage your network, to make a separate VLAN just for management.

This separates management traffic from your data traffic. This not only helps with performance, but also slightly increases security.

You can manage the switch through any reachable VLAN IP address.

If managing the switch from an external network, you must assign the switch a Default Gateway it can use to reach other networks.

The following command uses 192.168.0.1 as the Default Gateway address.

console(config)#ip default-gateway 192.168.0.1

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Setting login access on the switch.

To manage the switch you will need a username and password. To manage the switch via telnet or SSH, you will require an enable password. Input the following commands to configure login access. This is an example with the username as Dell, and password as P@$$w0rd. The enable password example uses ENP@$$w0rd. These are just examples and you should use more complicated, hard to guess credentials to secure your switch.

console>enable

console#configure

console(config)#username Dell password P@$$w0rd level 15

console(config)#enable password ENP@$$w0rd

Note: You may make multiple users on the switch, as well as different levels/privilege level of access. 0 is no access, 1 in read only, and 15 is read and write.

How to use iSCSI Targets on a Windows Server

How to use iSCSI Targets on a Windows Server

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Overview

The business-level Synology NAS servers are Microsoft^® Windows certified, which means by using the iSCSI Target Service, a Synology NAS seamlessly acts as dedicated storage server to provide iSCSI Target storage for your Hyper-V environment, which will be seen virtually as a local hard drive for as many clients as need be; only they are all stored in a centralized Synology server. Advanced management functions such as Thin Provisioning, iSCSI LUN Backup, MC/S (Multiple Connections per Session) and MPIO (Multipath I/O) are available on Synology NAS to strengthen the usability and stability of a network storage environment. As fully compliant with SPC-3 PR standard, Synology NAS supports Microsoft Windows^® Server Failover Clustering as well.
This article will guide you through the process of setting up iSCSI target connection from a Windows Server to your Synology NAS.

What is iSCSI?
iSCSI is an Internet Protocol based storage networking standard for linking data storage facilities. By carrying SCSI commands over IP networks, iSCSI can facilitate data transfers over local area networks (LANs), wide area networks (WANs), or the Internet. Through iSCSI, the space on storage server will be regarded as local disks by client's operation system. In reality, all data transferred to the disk are actually transferred over network to the storage server.
What is iSCSI Target and LUN?
In SCSI terminology, a LUN (logical unit number) represents an individually addressable (logical) SCSI device that is part of a physical SCSI device (called "Target"). An iSCSI environment emulates the connection to a SCSI hard disk. An iSCSI Target is like a connection interface, and LUNs are essentially numbered disk drives. When an iSCSI Target is connected by an iSCSI initiator (a client), all the LUNs mapped to the iSCSI Target are virtually attached to the client's operation system. Therefore, Initiators can establish and manage file systems on iSCSI LUNs, as they would a raw SCSI or IDE hard drive.

Contents

1. Before You Start
2. Create an iSCSI Target
3. Format iSCSI Target for Use on Windows

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1. Before You Start

This article assumes you have performed the following tasks:

• Hardware installation for Synology NAS.
• Create iSCSI LUNs and Targets on your Synology NAS.

After the setting above is finished,  you can refer to this article to know how to connect your iSCSI target with Multipath (MPIO).
Refer to Quick Installation Guide for more information about hardware and software installation. You can also see Synology NAS User's Guide (available at Synology's Download Center) for a general idea about topics related to this article.

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2. Create an iSCSI Target

This section will guide you through the process of setting up an iSCSI target on a Windows Server.

1. Open iSCSI Initiator in Windows under Control Panel > Administrative tools.

2. Go to Discovery tab and click on Discover Portal.

3. Enter the IP Address or the DNS Name of the Synology NAS, which is hosting the iSCSI Target, then click on OK.

4. Go to Targets tab.
5. Select the desired iSCSI target.
6. Click on Connect.

7. Click on OK if no advanced options are enabled on the iSCSI target on the Synology NAS.

8. Click on Advanced button if CHAP or any of the Advanced settings are enabled on the iSCSI Target on the Synology NAS.

9. Enter the name for CHAP.
10. Enter the target secret for CHAP.
11. Click on OK.
12. The iSCSI target is now connected to the Windows PC.

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3. Format iSCSI Target for Use on Windows

After an iSCSI Target has been connected on a Windows computer, it will have to be formatted before it can be used.

1. Open Computer Management under Control Panel > Administrative tools.

2. Select Disk Management on the left panel. Right click on the iSCSI Target (Disk1) and choose Online.

3. Right click on the iSCSI Target (Disk1) again and choose Initialize Disk.

4. A prompt will be displayed to initialize the newly added virtual drive. Please select a partition style most appropriate for the disk to be used then click on OK.

5. After the disk has been initialized, right click on the new disk (indicated by the black field), and select New Simple Volume.

6. Proceed forward with the Simple Volume Wizard.

7. Specify the volume size to use for the new hard drive, then click on Next.

8. Assign a drive letter for the new hard drive then click on Next.

9. Now your Windows Server has an additional drive E: created by Synology iSCSI target.

Note:
If you want to use Multipath I/O (MPIO) for the iSCSI targets on your Synology NAS, please do the following first:

1. Go to Storage Manager > iSCSI Target.
2. Find the desired iSCSI target, and click Edit > Advanced.
3. Tick Allow multiple sessions from one or more iSCSI initiators.
4. Click OK.

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Linux CPU Info

Linux CPU Info


# cat /proc/cpuinfo

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How to reset the root password in CentOS 6.6

Introduction

Booting straight up to GRUB is not the default boot method for CentOS 5 & 6.

This How-To was written to show you step by step the process of resetting the root password on your CentOS 5/6 installation.

Steps (7 total)

1

Boot or Reboot your CentOS installation

Expand

From the console ATL+CTRL+DEL will get you headed in the right direction.

2

Press Any Key

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After the installation reboots, it will come up to a boot countdown. Here, you can press any key, I don't have one either, but any other key works also.

This will bring you to the GRUB menu.

3

GRUB Menu

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From the GRUB menu, select the appropriate kernel version and press the 'e' key.
You will now be presented with the option menu for the kernel version.

4

Kernel Options Menu

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From this menu, select the kernel /vmlinuz-... line and press the 'e' key.
You will now be presented with the kernel boot options.

5

Change Kernel Boot Options

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Now we need to add to the end of this line one o the following:
1, s, or single
And now press Enter to save your changes.

6

Boot your temporary options

Expand

From this menu, you should already be on the kernel /vmlinuz... line.
Press the 'b' key to boot to these temporary options to allow you to recover your root account.

7

Set Root Password

Now you will boot up to the root shell and you can use passwd to set your new password.
You will be required to enter the password twice.
Once you have completed this, reboot and you have a new root password for your CentOS installation.

R610 서버 UEFI 모드 실행 시 멈춤 현상

OS 설치시 화면이 멈추는 현상이 발생

Keyboard 바꾸어 보거나 Front에 있는 USB 사용해보세요~~~~

Multiple IP Addresses to One Single Network Interface

ifcfg-eth0, the default interface for the Ethernet device. If you’ve attached second Ethernet device, then there would be an “ifcfg-eth1” device and so on for each device you’ve attached. These device network files are located in “/etc/sysconfig/network-scripts/” directory. Navigate to the directory and do “ls -l” to list all devices.

# cd /etc/sysconfig/network-scripts/
# ls -l

Sample Output

ifcfg-eth0   ifdown-isdn    ifup-aliases  ifup-plusb     init.ipv6-global
ifcfg-lo     ifdown-post    ifup-bnep     ifup-post      net.hotplug
ifdown       ifdown-ppp     ifup-eth      ifup-ppp       network-functions
ifdown-bnep  ifdown-routes  ifup-ippp     ifup-routes    network-functions-ipv6
ifdown-eth   ifdown-sit     ifup-ipv6     ifup-sit
ifdown-ippp  ifdown-tunnel  ifup-isdn     ifup-tunnel
ifdown-ipv6  ifup           ifup-plip     ifup-wireless

Let’s assume that we want to create three additional virtual interfaces to bind three IP addresses (172.16.16.126, 172.16.16.127, and 172.16.16.128) to the NIC. So, we need to create three additional alias files, while “ifcfg-eth0” keeps the same primary IP address. This is how we moving forward to setup three aliases to bind the following IP addresses.

Adapter            IP Address                Type
-------------------------------------------------
eth0              172.16.16.25            Primary
eth0:0            172.16.16.26            Alias 1
eth0:1            172.16.16.27            Alias 2
eth0:2            172.16.16.28            Alias 3

Where “:X” is the device (interface) number to create the aliases for interface eth0. For each alias you must assign a number sequentially. For example, we copying existing parameters of interface “ifcfg-eth0” in virtual interfaces called ifcfg-eth0:0, ifcfg-eth0:1 and ifcfg-eth0:2. Go into the network directory and create the files as shown below.

# cd /etc/sysconfig/network-scripts/
# cp ifcfg-eth0 ifcfg-eth0:0
# cp ifcfg-eth0 ifcfg-eth0:1
# cp ifcfg-eth0 ifcfg-eth0:2

Open a file “ifcfg-eth0” and view the contents.

[root@tecmint network-scripts]# vi ifcfg-eth0

DEVICE="eth0"
BOOTPROTO=static
ONBOOT=yes
TYPE="Ethernet"
IPADDR=172.16.16.125
NETMASK=255.255.255.224
GATEWAY=172.16.16.100
HWADDR=00:0C:29:28:FD:4C

Here we only need two parameters (DEVICE and IPADDR). So, open each file with VI editor and rename theDEVICE name to its corresponding alias and change the IPADDR address. For example, open files “ifcfg-eth0:0“, “ifcfg-eth0:1” and “ifcfg-eth0:2” using VI editor and change both the parameters. Finally it will look similar to below.

ifcfg-eth0:0

DEVICE="eth0:0"
BOOTPROTO=static
ONBOOT=yes
TYPE="Ethernet"
IPADDR=172.16.16.126
NETMASK=255.255.255.224
GATEWAY=172.16.16.100
HWADDR=00:0C:29:28:FD:4C

ifcfg-eth0:1

DEVICE="eth0:1"
BOOTPROTO=static
ONBOOT=yes
TYPE="Ethernet"
IPADDR=172.16.16.127
NETMASK=255.255.255.224
GATEWAY=172.16.16.100
HWADDR=00:0C:29:28:FD:4C

ifcfg-eth0:2

DEVICE="eth0:2"
BOOTPROTO=static
ONBOOT=yes
TYPE="Ethernet"
IPADDR=172.16.16.128
NETMASK=255.255.255.224
GATEWAY=172.16.16.100
HWADDR=00:0C:29:28:FD:4C

Once, you’ve made all changes, save all your changes and restart/start the network service for the changes to reflect.

[root@tecmint network-scripts]# /etc/init.d/network restart

To verify all the aliases (virtual interface) are up and running, you can use “ifconfig” or “ip” command.