The VMguy

Just a few technical papers released this past month on vmware.com but I thought I should review them because I think some of them are very important.

Dynamic Storage Provisioning – A very nice introduction to Thin Provisioning in vSphere.  The concept of Thin Provisioning is explained as well as when you want to use it.  Some interesting points I noted in the article: Thin disks expand in chunks the size of the vmdk’s block size (1MB by default) and the only way to defragment a vmdk currently? – Storage vMotion.

Performance Study of VMware Thin Provisioning – Very good read on the performance impact of thin provisioned disks vs. thick disks.  I was somewhat surprised by the results.  There’s not nearly as much of a performance impact as I thought there would be.  A very good read if you are looking to justify Thin Disks for some applications within your organization.

VMCI Socket Performance – This was a very interesting paper that I’m still scratching my head on.  VMCI is the interface that programmers can use to communicate between VM’s on a given host.  So if a programmer is writing an app and it requires 2 VMs that do a lot of communication to each other, they can communicate on the VMCI interface instead of traversing the TCP/IP network and going thru all of the networking stack.  This paper shows the performance of using VMCI instead of TCP/IP for Windows and Linux boxes.  I’m scratching my head because the results are not as linear as I would have expected and there are scenarios that perform much better or worse than others.  Take a read and make your own conclusions.

VMware vCenter Site Recovery Manager 4.0 Performance and Best Practices for Performance – I’m probably the #1 fan of SRM.  I think what SRM does for DR is like what a conductor does for an orchestra.  As you may know, SRM 4.0 now scales to 1,000 VMs.  It can take a while to optimize that number of VMs for recovery.  This paper is an excellent resource for optimizing the setup and config of SRM to scale effectively to a very large number of VMs.

Many of my users out there run Microsoft Cluster Services on ESX.  A great questions was asked of me today: have the rules changed with running MSCS on vSphere?  The answer is: a little.

There are 3 scenarios of MSCS clusters and ESX: Cluster-in-a-box (both MSCS nodes are on the same physical host – great for testing), cross-host (where each of the MSCS node VMs resides on different ESX hosts), and physical-virtual (where one MSCS node is physical, one is virtual).  The requirements for MSCS can change, even in the minor updates, so check the documentation often.  Here’s my compiled list of requirements/tips for MSCS on ESX 4.0:

• You are still limited to two-node clusters with MSCS on ESX 4.
• From a storage perspective, you can use local storage (for cluster-in-a-box) or Fiber Channel (for cross-host or physical-virtual clusters).  There is still no support for NFS or iSCSI (I personally think this is because FC and local storage have more predictable performance – although iSCSI is improving on this).
• If you are doing cross-host, both hosts must be running the same version of ESX (this just makes sense really).
• The MSCS node VMs cannot move as part of HA or DRS.  (HA is being a little redundant for MSCS, DRS is because MSCS is so hyper-sensitive to network connectivity that even a ping loss could failover the MSCS cluster).
• You cannot use MSCS with Fault Tolerance  (i.e. FT VM’s can reside on the same physical ESX hosts, but MSCS node VMs cannot run as FT pairs)
• You cannot vMotion MSCS node VM’s.  (Same reason as DRS).
• You cannot use N-Port ID Virtualization (NPIV)
• If you are using FC and using the native multipathing in ESX, you cannot use round robin as a path policy.
• You must use VM hardware version 7 with ESX/ESXi 4.0 (if you migrated the VMs from ESX 3.5 or before, make sure to upgrade your VM hardware version)
• Failover clustering with Windows Server 2008 is not supported with virtual compatibility mode RDM’s, for Win2008 use physical compatibility mode RDMs.
• You cannot use thin-provisioned disks for the Windows OS vmdk’s, they have to be thick.
• For Win2000 and Win2003 use LSI Logic Parallel as the controller type for the shared storage.  For Win2008 use LSI Logic SAS.
• For physical-virtual MSCS clusters, use RDMs in physical compatibility mode (this just makes sense if you think about it)
• You cannot run storage multipathing software in the VMs or on ESX (i.e. no PowerPath VE).
• You cannot over-commit memory for the MSCS node VMs, set the Memory Reservation option for each of the nodes to the amount of memory assigned to the virtual machine.
• Set the disk I/O timeout to 60 sec. or more (HKLM\System\CurrentControlSet\Services\Disk\TimeOutValue) in the registry.

You can find all the details and steps walking you thru the setup of MSCS on ESX in this article .  If you’re not on vSphere yet but you want to run MSCS nodes as VMs, you can find the proper docs for your version of ESX in a freshly updated KB article located here .

Some good ones came out last week.  Let’s take a look:

• VMware vSphere 4: Exchange Server on NFS, iSCSI, and Fibre Channel – a very nice paper on how NFS, iSCSI, and Fiber Channel performed running a very large number of mailboxes on Exchange.
• Performance Best Practices for VMware vSphere 4.0 – Absolutely a must-read for new administrators and a new addition for my Admin Bookmarks page .  This is also a great review for those looking to upgrade to vSphere.
• Using Local Disks in VMware View Deployment – A very interesting idea: in a remote office running local ESX servers, use a Storage Appliance to gain HA with local disks only for desktops running in View.
• VMware Fault Tolerance Recommendations and Considerations on VMware vSphere 4 – The defacto-standard read if you are planning to use FT in your enviornment.  This article is a keeper of all of the current ins-and-outs of FT.
• What’s New in VMware vSphere 4: Virtual Networking – a great reference for all of the new capabilities in networking in 4.0.  Very detailed and technical.
• What Is New in VMware vSphere 4: Storage – The complete list of everything that’s new from a storage perspective.  From thin-provisioning to Pluggable Storage Architecture, it’s all there.

While this utility is still experimental, it can be very helpful.  For those trying out Data Recovery to backup your VM’s, this is a great way to mount the point-in-time images that Data Recovery catches.

For instance, this utility only works on XP, Vista, Server 2003 and Server 2008.  It allows you to run a command from the command line pointing it at you Data Recovery appliance.  The utility then responds with a list of all of the restore points the machine you are running on has available.  You can then select a restore point from the list and the utility mounts that restore point as additional drive(s) on the current VM.  You can then use explorer to grab the single files you need out of the backup image.  When completed, you type the "unmount" command on the command line which will unmount all of the disks mounted by the utility.

It is still in the Experimental stage but looks very promising for admins just needing to grab a few files out of Data Recovery.

You can grab it and the docs for it in the Data Recovery download section here .

There were 5 new technical papers published last week.  Some really good reading for administrators and architects.

• VMware VDI Storage Considerations <-A great paper which discusses which protocol to use, how to lay out datastores, etc for View implementations.
• Running Microsoft Office SharePoint Server 2007 on VMware Infrastructure <-A great paper for those wanting to virtualize Sharepoint.
• Automating SharePoint Provisioning and Deployment on VMware vSphere <- This paper describes how you can setup sharepoint sites in templates for rapid deployment of new sharepoint instances.
• Virtualizing a Windows Active Directory Domain Infrastructure <- I know many have already done this  but it is still a great reference and includes best practices.  Definately want to confirm your settings against this white paper
• SAP Solutions on VMware vSphere: High Availability <- A good white paper on the availability options for SAP implementations and the benefits of each.