Posts Tagged ‘Cluster’

Setup for Microsoft cluster service

April 1st, 2009

Setting up a Microsoft cluster on VMware used to be a fairly straight forward task with a very minimal set of considerations. Over time, the support documentation has evolved into something that looks like it was written by the U.S Internal Revenue Service. I was an Accountant in my previous life and I remember Alternative Minimum Tax code that was easier to follow than what we have today, a 50 page .PDF representing VMware’s requirements for MSCS support. Even with that, I’m not sure Microsoft supports MSCS on VMware. The Microsoft SVVP program supports explicit versions and configurations of Windows 2000/2003/2008 on ESX 3.5 update 2 and 3, and ESXi 3.5 update 3 but no mention is made regarding clustering. I could not find a definitive answer on the Microsoft SVVP program site other than the following disclaimer:

For more information about Microsoft’s policies for supporting software running in non-Microsoft hardware virtualization software please refer to http://support.microsoft.com/?kbid=897615. In addition, refer to http://support.microsoft.com/kb/957006/ to find more information about Microsoft’s support policies for its applications running in virtual environments.

At any rate, here are some highlights of MSCS setup on VMware Virtual Infrastructure, and by the way, all of this information is fair game for the VMware VCP exam.

Prerequisites for Cluster in a Box

To set up a cluster in a box, you must have:

* ESX Server host, one of the following:

* ESX Server 3 - An ESX Server host with a physical network adapter for the

service console. If the clustered virtual machines need to connect with external

hosts, then an additional network adapter is highly recommended.

* ESX Server 3i - An ESX Server host with a physical network adapter for the

VMkernel. If the clustered virtual machines need to connect with external

hosts, a separate network adapter is recommended.

* A local SCSI controller. If you plan to use a VMFS volume that exists on a SAN, you

need an FC HBA (QLogic or Emulex).

You can set up shared storage for a cluster in a box either by using a virtual disk or by

using a remote raw device mapping (RDM) LUN in virtual compatibility mode

(non‐pass‐through RDM).

When you set up the virtual machine, you need to configure:

* Two virtual network adapters.

* A hard disk that is shared between the two virtual machines (quorum disk).

* Optionally, additional hard disks for data that are shared between the two virtual

machines if your setup requires it. When you create hard disks, as described in this

document, the system creates the associated virtual SCSI controllers.

Prerequisites for Clustering Across Boxes

The prerequisites for clustering across boxes are similar to those for cluster in a box.

You must have:

* ESX Server host. VMware recommends three network adapters per host for public

network connections. The minimum configuration is:

* ESX Server 3 - An ESX Server host configured with at least two physical

network adapters dedicated to the cluster, one for the public and one for the

private network, and one network adapter dedicated to the service console.

* ESX Server 3i - An ESX Server host configured with at least two physical

network adapters dedicated to the cluster, one for the public and one for the

private network, and one network adapter dedicated to the VMkernel.

* Shared storage must be on an FC SAN.

* You must use an RDM in physical or virtual compatibility mode (pass‐through

RDM or non‐pass‐through RDM). You cannot use virtual disks for shared storage.

Prerequisites for Standby Host Clustering

The prerequisites for standby host clustering are similar to those for clustering across

boxes. You must have:

* ESX Server host. VMware recommends three network adapters per host for public

network connections. The minimum configuration is:

* ESX Server 3 - An ESX Server host configured with at least two physical

network adapters dedicated to the cluster, one for the public and one for the

private network, and one network adapter dedicated to the service console.

* ESX Server 3i - An ESX Server host configured with at least two physical

network adapters dedicated to the cluster, one for the public and one for the

private network, and one network adapter dedicated to the VMkernel.

* You must use RDMs in physical compatibility mode (pass‐through RDM).

You cannot use virtual disk or RDM in virtual compatibility mode

(non‐pass‐through RDM) for shared storage.

* You cannot have multiple paths from the ESX Server host to the storage.

* Running third‐party multipathing software is not supported. Because of this

limitation, VMware strongly recommends that there only be a single physical path

from the native Windows host to the storage array in a configuration of

standby‐host clustering with a native Windows host. The ESX Server host

automatically uses native ESX Server multipathing, which can result in multiple

paths to shared storage.

* Use the STORport Miniport driver for the FC HBA (QLogic or Emulex) in the

physical Windows machine.

Cluster in a Box Cluster Across Boxes Standby Host Clustering
Virtual disks Yes No No
Pass-through RDM (physical compatibility mode) No Yes Yes
Non-pass-through RDM (virtual compatibility mode) Yes Yes No

Caveats, Restrictions, and Recommendations

This section summarizes caveats, restrictions, and recommendation for using MSCS in

a VMware Infrastructure environment.

* VMware only supports third‐party cluster software that is specifically listed as

supported in the hardware compatibility guides. For latest updates to VMware

support for Microsoft operating system versions for MSCS, or for any other

hardware‐specific support information, see the Storage/SAN Compatibility Guide for

ESX Server 3.5 and ESX Server 3i.

* Each virtual machine has five PCI slots available by default. A cluster uses four of

these slots (two network adapters and two SCSI host bus adapters), leaving one

PCI slot for a third network adapter (or other device), if needed.

* VMware virtual machines currently emulate only SCSI‐2 reservations and do not

support applications using SCSI‐3 persistent reservations.

* Use LSILogic virtual SCSI adapter.

* Use Windows Server 2003 SP2 (32 bit or 64 bit) or Windows 2000 Server SP4.

VMware recommends Windows Server 2003.

* Use two‐node clustering.

* Clustering is not supported on iSCSI or NFS disks.

* NIC teaming is not supported with clustering.

* The boot disk of the ESX Server host should be on local storage.

* Mixed HBA environments (QLogic and Emulex) on the same host are not

supported.

* Mixed environments using both ESX Server 2.5 and ESX Server 3.x are not

supported.

* Clustered virtual machines cannot be part of VMware clusters (DRS or HA).

* You cannot use migration with VMotion on virtual machines that run cluster

software.

* Set the I/O time‐out to 60 seconds or more by modifying

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Disk\

TimeOutValue.

The system might reset this I/O time‐out value if you recreate a cluster. You must

reset the value in that case.

* Use the eagerzeroedthick format when you create disks for clustered virtual

machines. By default, the VI Client or vmkfstools create disks in zeroedthick

format. You can convert a disk to eagerzeroedthick format by importing,

cloning, or inflating the disk. Disks deployed from a template are also in

eagerzeroedthick format.

* Add disks before networking, as explained in the VMware Knowledge Base article

at http://kb.vmware.com/kb/1513.

phew!

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Make VirtualCenter highly available with VMware Virtual Infrastructure

November 17th, 2008

A few days ago I posted some information on how to make VirtualCenter highly available with Microsoft Cluster Services.

Monday Night Football kickoff is coming up but I wanted follow up quickly with another option (as suggested by Lane Leverett): Deploy the VirtualCenter Management Server (VCMS) on a Windows VM hosted on a VMware Virtual Infrastructure cluster. Why is this a good option? Here are a few reasons:

  1. It’s fully supported by VMware.
  2. You probably already have a VI cluster in your environment you can leverage. Hit the ground running without spending the time to set up MSCS.
  3. Removing MSCS removes a 3rd party infrastructure complexity and dependency which requires an advanced skill set to support.
  4. Removing MSCS removes at least one Windows Server license cost and also removes the need for the more expensive Windows Enterprise Server licensing and the special hardware needs required by MSCS.
  5. Green factor: Let VCMS leverage the use of VMware Distributed Power Management (DPM).

How does it work? It’s pretty simple. A virtualized VCMS shares the same advantages any other VM inherently has when running on a VMware cluster:

  1. Resource balancing of the four food groups (vProcessor, vRAM, vDisk, and vNIC) through VMware Distributed Resource Scheduler (DRS) technology
  2. Maximum uptime and quick recovery via VMware High Availability (HA) in the event of a VI host failure or isolation condition (yes, HA will still work if the VCMS is down. HA is a VI host agent)
  3. Maximum uptime and quick recovery via VMware High Availability (HA) in the event of a VMware Tools heartbeat failure (ie. the guest OS croaks)
  4. Ability to perform host maintenance without downtime of the VCMS

A few things to watch out for (I’ve been there and done that, more than once):

  1. If you’re going to virtualize the VCMS, be sure you do so on a cluster with the necessary licensed options to support the benefits I outlined above (DRS, HA, etc.) This means VI Enterprise licensing is required (see the licensing/pricing chart on page 4 of this document). I don’t want to hide the fact that a premium is paid for VI Enterprise licensing, but as I pointed out above, if you’ve already paid for it, the bolt ons are unlimited use so get more use out of them.
  2. If your VCMS (and Update manager) database is located on the VCMS, be sure to size your virtual hardware appropriately. Don’t go overboard though. From a guest OS perspective, it’s easier to grant additional virtual resources from the four food groups than it is to retract them.
  3. If you have a power outage and your entire cluster goes down (and your VCMS along with it), it can be difficult to get things back on their feet while you don’t have the the use of the VCMS. Particularly if you’ve lost the use of other virtualized infrastructure components such as Microsoft Active Directory. Initially it’s going to be command line city so brush up on your CLI. It really all depends on how badly the situation is once you get the VI hosts back up. One example I ran into is host A wouldn’t come back up. Host B wasn’t the registered owner of the VM I needed to bring up. This requires running the vmware-cmd command to register the VM and bring it up on host B.

Well, I missed the first few minutes of Monday Night Football, but everyone who reads (tolerates) my ramblings is totally worth it.

Go forth and virtualize!

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Make VirtualCenter highly available with Microsoft Cluster Services

November 12th, 2008

When VirtualCenter was first introduced, many could make the argument that VC was simply a utility class service that provided centralized management for a virtual infrastructure. If the VirtualCenter Management Server (VCMS) was rebooted in the middle of the day or if the VC services were stopped for some reason, it wasn’t too big of a deal providing the outage didn’t interrupt a key task such as a VMotion migration or a cloning process.

Times are changing. VirtualCenter is becoming a fairly critical component in the VI and high availability of VC and the VCMS is becoming increasingly important. Several factors have contributed to this evolution. To identify just a few:

  • Virtual infrastructures are growing rapidly in the datacenter. The need for a functioning centralized management platform increases exponentially.
  • Increased and more granular VC alerting capabilities are relied upon to keep administrators updated with timely information about the load and health of the VI.
  • The introduction of more granular role base security extended Virtual Infrastructure Client or Web Access deployment to more users and groups in the organization increasing dependability on VC and visibility of downtime.
  • The exposure of the VC API/SDK encouraged many new applications and tools to be written against VC. I’m talking about tools that provide important functions such as backup, reporting, automation, replication, capacity analysis, sVMotion, etc. Without VC running, these tools won’t work.
  • The introduction of plugins. Plugins are going to be the preferred bolt on for most administrators because they snap in to a unified management interface. Obvious dependency on VC.
  • The introduction of new features native to VC functionality. DRS, HA, DPM, VCB, Update Manager, Consolidation, snapshot manager, FT, SRM, etc. Like the bullet above, all of these features require a healthy functioning VCMS.
  • The Virtual Datacenter OS was announced at VMworld 2008 and is comprised of the following essential components: Application vServices, Infrastructure vServices, Cloud vServices, and Management vServices. I don’t know about you, but to me those all sound like services that would need to be highly available. While it is not yet known exactly how existing VI components transform into the VDC-OS, we know the components are going to be integral to VMware’s vision and commitment to cloud computing which needs to be highly available, if not continuously available.

VirtualCenter has evolved from a cornerstone of ESX host management into the the entire foundation on which the VI will be built on. Try to imagine what the impacts will be in your environment if and when VirtualCenter is down now and in the future. Dependencies may have waltzed in that you didn’t realize.

A single VCMS design may be what you’re used to, but fortunately there exists a method by which VC may be made highly available on a multi-node Microsoft Cluster. This document, written by none other than my VI classroom training instructor Chris Skinner, explains how to cluster VirtualCenter 2.5.

If you’re on VirtualCenter 2.0.x, follow this version of the document instead.

Update:  Follow up post here.

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