<div>
Often this is because your domain controller is one of the VMs, and without it the services will not start.
</div>


<div>
Gareth,<br />
<br />
Well, the Domain controllers are located on physical machines not VMs.
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<div>
Hmm, not that then. What about the central management service for Xenserver, do you have one?
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<div>
Center Management Service mean? if you are talking about XenCenter yes i have.
</div>


<div>
Is that physical, or a VM? HA depends on something managing the resources; my only experience is VMWare, unfortunately.
</div>


<div>
yes but here the reason is that all resources were disconnected, i hope someone from citrix will reply.. Thank you sir.
</div>


<div>
Yes &nbsp;Joharder the storage was disconnected.....<br />
eeroot yes the restart priority is configured and the server failure limit(2).
</div>


<div>
What was the cause of your network failure?
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<div>
The Entire switches was done for a while.
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<div>
So what power failure?<br />
<br />
if so dont you have your switches on a UPS?
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<div>
conciseness and completeness
</div>


<div>
<div class="content wysiwyg-content">
We have five xenserver host machines which has around 20 VMs last night we had a network failure all host machines were disconnected from switch where they stop connection with share storage, later once we recovered the connectivity found most of the VMs were turned off, none of them &nbsp;turned on automatically(HA is enabled), can you please share your ideas on the same.<br />
<br />
for me this was because of no host available at that time to restart VMs themselves somewhere in other physical machine so that could be the reason that they went off.<br />
<br />
Regards<br />
Abdul
</div>
</div>


We have five xenserver host machines which has around 20 VMs last night we had a network failure all host machines were disconnected from switch where they stop connection with share storage, later once we recovered the connectivity found most of the VMs were turned off, none of them  turned on automatically(HA is enabled), can you please share your ideas on the same.

for me this was because of no host available at that time to restart VMs themselves somewhere in other physical machine so that could be the reason that they went off.

Regards
Abdul

Network Failure

VMware, a software company founded in 1998,  was one of the first commercially successful companies to offer x86 virtualization. The storage company EMC purchased VMware in 1994. Dell Technologies acquired EMC in 2016. VMware’s parent company is now Dell Technologies.

VMware has many software products that run on desktops, Microsoft Windows, Linux, and macOS, which allows the virtualizing of the x86 architecture.  Its enterprise software hypervisor for servers, VMware vSphere Hypervisor (ESXi), is a bare-metal hypervisor that runs directly on the server hardware and does not require an additional underlying operating system.

VMware

Citrix is the synonym for the virtualization and application infrastructure systems developed by the company of the same name. Main areas are application virtualization, Software-As-A-Service (SaaS), cloud-computing and networking. The two most well-known are Citrix XenApp or Citrix CloudPlatform.

Citrix

Virtualization is the act of creating a virtual (rather than actual) version of something, including (but not limited to) a virtual computer hardware platform, operating system (OS), storage device, or computer network resources. Virtualization is usually the creation of a system that executes separate from the underlying hardware resources, or the creation of an entire desktop for systems located elsewhere, similar to thin clients.

Virtualization

Servers are computing devices that are similar to desktop computers in that they have the same basic components, but are significantly different in size, configuration and purpose. Servers are usually accessed over a network, and many run unattended, without a computer monitor, input device, audio hardware or USB interfaces. Many servers do not have a graphical user interface (GUI), and are configured and managed remotely. Servers typically include hardware redundancy such as dual power supplies, RAID disk systems, and ECC memory, along with extensive pre-boot memory testing and verification. Critical components might be hot swappable, and to guard against overheating, servers might have more powerful fans or use water cooling.

Server Hardware

Networking hardware includes the physical devices facilitating the use of a computer network. Typically, networking hardware includes gateways, routers, network bridges, modems, wireless access points, networking cables, line drivers, switches, hubs, and repeaters. But it also includes hybrid network devices such as multilayer switches, protocol converters, bridge routers, proxy servers, firewalls, network address translators, multiplexers, network interface controllers, wireless network interface controllers, ISDN terminal adapters and other related hardware.

Networking Hardware-Other

A server is a computer program or a machine that waits for requests from other machines or software (clients) and responds to them. This architecture is called the client–server model. The clients may run on the same computer or may connect to the server over a network. The purpose of a server is to share data or hardware and software resources among clients. Typical computing servers are database servers, file servers, mail servers, print servers, web servers, game servers, and application servers.

Server Software

Microsoft Virtual Server was a virtualization solution that facilitated the creation of virtual machines on the Windows XP, Windows Vista and Windows Server 2003 operating systems. Virtual machines are created and managed through a web-based interface that relies on Internet Information Services (IIS) or through a Windows client application tool called VMRCplus. Features included Linux guest operating system support, Virtual Disk Precompactor, symmetric multiprocessing (SMP), x64 host operating system support, the ability to mount virtual hard drives on the host machine and additional operating systems support, including Windows Vista, and a volume shadow copy writer.

Microsoft Virtual Server

Windows Server 2012 is the server version of Windows 8 and the successor to Windows Server 2008 R2. Windows Server 2012 is the first version of Windows Server to have no support for Itanium-based computers since Windows NT 4.0. Windows Server 2012, now in its second release (Windows Server 2012 Release 2) includes Foundation, Essentials, Standard and Datacenter, and does not support IA-32 or IA-64 processors.

Windows Server 2012

Hyper-V is a native hypervisor; it can create virtual machines on x86-64 systems and supersedes Windows Virtual PC as the hardware virtualization component of the client editions of Windows NT. A server computer running Hyper-V can be configured to expose individual virtual machines to one or more networks. Hyper-V Server supports remote access via Remote Desktop Connection. Administration and configuration of the host OS and the guest virtual machines is generally done over the network.

Hyper-V

The Microsoft Server topic includes all of the legacy versions of the operating system, including the Windows NT 3.1, NT 3.5, NT 4.0 and Windows 2000 and Windows Home Server versions.