How to Check if Your CPU Supports Second Level Address Translation (SLAT)

Windows 8 will bring a lot of new features to the Windows computing environment, one of which will be Hyper-V. In order to run Hyper-V your processor must support Second Level Address Translation (SLAT). Read on to find out if your processor supports SLAT.

What is SLAT?

Second Level Address Translation is a technology introduced in both Intel and AMD flavors of processors. Both companies call their version of the technology different names, Intel’s version is called EPT(Extended Page Tables) and AMD calls theirs RVI (Rapid Virtualization Indexing). Intel introduced Extended Page Tables in its processors that were built on the Nehalem architecture, while AMD only introduced RVI in their third generation of Opteron processors codenamed Barcelona. Hyper-V uses this to perform more VM memory management functions and reduce the overhead of translating guest physical addresses to real physical addresses. By doing this, Hypervisor CPU time is significantly reduced, and more memory is saved for each VM.

How it works

The processor has a Translation Lookaside Buffer (TLB) that supports virtual to physical memory address translation. A TLB is a cache on the processor that contains recently used mappings from the page table. When a virtual to physical address translation is required, the TLB checks it’s cache to determine whether or not it contains the mapping information. If the TLB contains a match, the physical memory address is provided and the data is access. If the TLB doesn’t contain a record, a page error occurs, and the Windows checks the page table for the mapping information. If Windows finds a mapping, it is written to the TLB, the address translation takes place, and then the data is accessed. Because of this buffer, the hypervisors overhead is substantially decreased.

So what?

With all the hype surrounding Windows 8, it has been made known that Windows 8 will come with Hyper-V as a vitalization platform. While that might not appeal to everyone at first glance, it has been thought that this will be the only form of backwards compatibility, somewhat like XP Mode. SLAT will be required for Hyper-V in Windows 8.

How do I know if I have SLAT?

To find out if your processor supports SLAT, you will need to download a copy of CoreInfo. Once you have downloaded it you will need to extract it. You should extract it so that coreinfo is in the root of your C:\ drive. To see if your processor supports SLAT you will need to run “coreinfo.exe -v”.

On an Intel if your processor supports SLAT it will have an asterix in the EPT row. This is seen in the screenshot below.
On an AMD if your processor supports SLAT it will have an asterix in the NPT row.

If your processors dont support SLAT you will see a dash in the EPT or NPT rows.

1.) Run the CMD command prompt as an Administrator
2.) Browse to the CoreInfo folder on your C: drive
3.) Enter the command CoreInfo.exe -v

How to: Building a Hyper-V host using the boot from VHD feature

A great new feature within Windows 7 and Windows 2008 is boot from VHD. Yesterday I downloaded the Windows Server 2012 Release Candidate version. The executable is self-extracting withs contains a sysprepped VHD file, cool!! I configured my Windows 7 desktop to boot from this VHD and voila, there’s my Windows Server 2012!! 🙂

1.) Download the self-extracting executable file from Microsoft Download
2.) Run the executable. There’s a new folder created expandedVHD
3.) Within this folder there’s a VHD file
4.) Open the Computer Management and select Diskmanagement
5.) Right-click on Diskmanagement and select Attach VHD
6.) Browse to the VHD file in the expandedVHD folder and select the file
7.) The VHD file is mounted now and there’s a driveletter attached. In my example D:
8.) You can browse the D:\ disk within the Windows Explorer to view the files inside the VHD
9.) Open a command prompt (with Administrative Rights) and type:
bcdboot D:\Windows
This will modify the bootrecord, so you’re able to boot from this VHD
10.) Open a command prompt in type MSCONFIG
11.) Select the second tab and view the new boot option “Windows Server 2012 Release Candidate (D:\Windows)”
12.) Reboot your machine and select Windows Server 2012 Release Candidate in the bootmenu
13.) After completing the sysprep phase, you’ve a Windows Server 2012 up and running
14.) Whitin the Server Manager Dashboard select Add roles and features
15.) Select the Hyper-V role
16.) Select the default locations for the Hyper-V files and hit Next
17.) The Hyper-V role will be installed now
18.) Reboot your system and the Hyper-V host is ready to use
19.) From the Hyper-V Manager you’re able to a create a new virtual machine. In my example a Windows Server 2008 R2 VM









Windows 8 Hyper-V Feature Glossary

Within a few months, the release of Windows 8 is there. Windows 8 means also a new version of Hyper-V, that’s great news! Hyper-V 3.0 means also a lot of new features and possibilities. MVP Aidan Finn posted a great feature glossary. In this blogpost Aidan gives an overview of all the new great features whitin Hyper-V 3.0. Special thanks to him, great job!

Feature Description
Active/Active File Share Clusters Using CSV and a witness as features, you can create an active/active file share failover cluster. This is supported for services that use large file with little metadata access, e.g. Hyper-V. In other words, you can use a file share cluster instead of a SAN for your Hyper-V cluster.
Asymmetric Hyper-V Cluster A single cluster with Hyper-V and Active/Active File Server roles
BitLocker & HA The ability to encrypt parent partition disks and cluster shared volumes using BitLocker for physical security of virtual machines and data. Uses a Cluster Name Object (CNO) for locking and unlocking CSVs.
Boot From SAN VMs can boot from iSCSI or Fibre Channel disks, rather than just the traditional VHD(X)
Cluster Aware Updating Automate the Windows Update process for clustered hosts. It automatically drains hosts of VMs and patches them in order.
Cluster Scalability Up to 63 hosts and up to 4,000 VMs
Concurrent Live Migration Perform many live migrations at once between two hosts, with the only limit being your bandwidth.
Converged Fabrics Simplified host networking by merging all of the various LAN, SAN, and cluster networks to a reduced number of teamed high bandwidth NICs.
CSVFS CSVs are easier to backup. Although they are still NTFS, they appear as CSVFS for easier identification as CSVs in disk administration tools.
Data Center Bridging DCB enables very different networking protocols to run on the same network infrastructure, and therefore helps enable the convergence of LANs and SANs onto a single unified fabric.
Dedup & Thin Provisioning Windows 8 can use just the storage space that is required by not needlessly storing “empty” space (thin provisioning) or redundant data (de-duplication)
DHCP Guard Ban DHCP traffic from rogue DHCP services running in VMs.
Direct I/O Backup VMs on Cluster Shared Volumes (CSVs) can be backed up without Redirected I/O (Mode/Access).
Drain VMs Easy host maintenance by draining VMs from the host
Dynamic Memory Minimum Memory Once a VM has booted it can balloon down to the Minimum setting if it is underutilising the memory allocated by the Startup setting.
Dynamic Virtual Machine Queue DMVQ will dynamically span processing VMQ n/w traffic across more than one CPU. It will automatically scale up and scale down the CPU utilisation based on demand
Extensibale Hyper-V Switch Replacing the virtual network, this intelligent virtual switch offers extensibility for partners, with products already announced by the likes of Cisco and Brocade.
Failover Prioritisation Order the failover of VMs based on application dependencies.
Guest Application Monitoring Configure Failover Clustering to restart or failover VMs based on monitored events that occur inside of the VM.
Guest NUMA Virtual machines are aware of Non-Uniform Memory Architecture and can schedule processes in accordance with memory placement at the physical layer. Guest NUMA can be customised on a per-VM basis.
High Availability A feature of Failover Clustering, allowing a service or VM to failover from one host to another, enabling machine fault tolerance and maintenance windows with minimised service downtime.
Host Scalability 160 physical logical processors, up to 2 TB RAM, removal of the 8:1 logical to virtual processor limit.
Hyper-V Replica Asynchronous replication of virtual machines from one location to another, supporting VSS snapshots, failover, and IP address injection.
IPsec Task Offload IPsecTO moves this workload from the main host’s CPU to a dedicated processor on the network adapter
Live Migration Move a virtual machine from one host to another. This does not require Failover Clustering in Windows Server 8.
Live Storage Migration Physically relocate a VM by first copying it and synchronising I/O until the source and destination are identical. Can leverage Offloaded Data Transfer (ODX) in a SAN to make the process up to 90% faster.
Multi-Tenancy With features such as Network Virtualisation, PVLANs, and PORT ACLs, you can use Windows 8 Hyper-V in multi-tenant environments such as IaaS public cloud hosting.
Native 4k disk support This will allow disk alignment for VHDs created on 4k sector physical disks, thus improving performance.
Network Virtualisation The abstraction of virtual IP address from physical IP address, allowing easier mobility of VMs across fabrics. This is a key feature of multi-tenancy.
NIC Teaming Team NICs in Windows Server 8 (and Hyper-V) for bandwidth aggregation and network path fault tolerance. The NICs do not need to be from the same manufacturer.
Online Disk Repair Windows 8 will detect storage faults and incrementally fix them with brief delays to I/O traffic that don’t interrupt it. Should replace the need for offline chkdsk.
Port ACLs Define allowed communication paths between virtual machines based on IP range or MAC address.
PowerShell Hyper-V has around 150 built-in PowerShell cmdlets. 100% of features are revealed via PowerShell.
PVLAN VLANs are slow to configure in the physical network and there is a limit on how many can be configured. Private VLANs allow Hyper-V to replace this physical networking feature.
QoS Specify maximum limits and minimum guarantees for network communications.
Receive Side Coalescing RSC aggregates packets from the same TCP/IP flow into one larger packet, reducing per-packet processing costs for faster TCP/IP processing
Receive Side Scaling RSS allows the receive side network load from a network adapter to be shared across multiple processors
Remote Direct Memory Access RDMA enables more efficient access of data on file shares.
Resource Metering Measure CPU, network and memory on a per-VM basis. This data is stored with the VM and moves with the VM.
Single Root I/O Virtualisation SR-IOV allows a physical NIC to appear to be a number of physical NICs, and allows virtual machine networking to bypass the virtual switch.
SMB 2.2 SMB 2.2 supports RDMA and is in Windows Server 8. Storage of VMs is supported on SMB 2.2. file shares. With NIC teaming, you get multi-channel SMB.
Snapshot Live Merge You do not have to shut down a VM to merge a snapshot in Windows 8, resolving a major support issue.
Storage Pools An aggregation of disks without any RAID. They can be as loosely coupled as a bunch of USB drives. The disks can be different sizes. A pool does not appear in Explorer. You can create Storage Spaces from Storage Pools. This is one of the storage types you could use to create a scalable and continuously available active/active file share cluster.
Storage Spaces A thinly provisioned slice of storage from a storage pool. Can be a 2-copy-mirror (Like RAID 1 in concept and performance), 3-copy-mirror, or parity (like RAID 5 in concept and performance) storage space. Can be lots of spaces in a single pool. A space is divided up into slabs across disks in the pool depending on the fault tolerance chosen. Advanced configuration allows you to choose which pool disks to use.
Unified Tracing Enables network diagnostics in the Hyper-V Extensible Switch
VHDX The default virtual disk type, expanding up to 16 TB, and supporting dynamic and fixed types.
Virtual Fibre-Channel Adapter A host’s fibre channel adapter can be virtualised, thus enabling VMs to have their own WWN and direct access to the SAN.
Virtual Machine Scalability 32 virtual processors, 512 GB RAM
Virtualisation Aware Domain Controllers Windows Server 8 domain controllers are aware if they are Windows 8 Hyper-V VMs. This prevents USN rollback (VM restore or snapshot application).
Windows 8 Client Hyper-V is included in the client operating system for free. It’s the same Hyper-V as in the server, offering VM mobility and an easy introduction to Microsoft’s enterprise virtualisation.  The client version of Hyper-V requires Second Level Address Translation (SLAT)  in the CPU (Intel EPT, AMD RVI/NPT).  This is not a requirement in the server version, but it is recommended.

It is a long list of features, and absolutely great to see all this new possibilities. I can’t wait until the release of Windows 8… 🙂

Altaro – VSS Crash-Consistent vs. Application-Consistent VSS Backups (part 2 of 2)

The second and final part of the VSS Crash-Consistant vs. Application-Consistent VSS Backups is online! Today Altaro posted the second part of this great blogpost. In this part the opportunities are explained whitin Hyper-V, to make a succesvol backup of your environment. A nice thing is the explanation what is happening when taking a backup of a CSV volume.


You can find the first part of this blogpost through the following URL.



Altaro – VSS Crash-Consistent vs. Application-Consistent VSS Backups (part 1 of 2)

Today Altaro posted a great article about VSS Crash-Consistent vs. Application-Consistent VSS Backups. In this first blogpost the Crash-Consistant Backups are compared to Application-Consistant VSS Backups.


NOTE: This is the first blog post in a 2-series post. Subscribe to Altaro’s Blog to get notified when the second article is posted. You can subscribe at the top-right of this page.

How to: Using Differencing Disk and Sysprep Image to create Hyper-V guest on Windows Server 2008 R2

When you have to create an testlab environment with multiple servers, it is a big job to install all the servers. Even when you are using Hyper-V in this environment. You manually have to install all the servers or make clones of another virtual machine. In this scenario it is very usefull to make use of Differencing Disks within Hyper-V. A Differencing Disks are linked to an master VHD file. This master VHD file is a virtual machine that has been sysprepped.

Basically, all of the main reads for the VMs created with a differencing disk come from the master VHD, while any changes (writes) are written to the differencing disk. The differencing disk will remain fairly small, because the amount of change should be minimal. You’re probably looking at around a couple of GBs per differencing disk. With a differencing disk you can build multiple machines with the same parent sysprep image.

You can build this environment by following the next steps;

1.) Create a new virtual machine within Hyper-V
2.) Install the Operating System with the specific updates
3.) Optionally you can install some base applications
4.) Sysprep the virtual machine. You can use the following command:
%windir%\system32\sysprep\sysprep.exe /generalize /shutdown
5.) Now the virtual machine is sysprepped and power off
6.) Create a new virtual machine (or multiple)
7.) Create a new VHD using differencing disk
8.) Navigate to the base VHD file you’ve just created (the sysprepped virtual machine)
9.) Edit some other settings within the virtual machine (cores, memory, NIC, etc.)
10.) Boot the new virtual machine
11.) Walk through the “First Run” steps of the Operating System
12.) The new virtual machine is now ready to use
13.) Navigate to the differencing disk (VHD) and see how big it is…right it’s really small! 🙂