Understanding the difference between traditional cluster Disk Vs. Cluster Shared Volumes (CSV) ?
I touched base with Windows after a substantial gap, and that happened during the course of MCSE 2012 Server Infrastructure certification, I got introduced to various new features and technologies that were introduced in Server 2012, and one of which I liked the most is the improvement in CSV 2.0. The whole concept of CSV and it's benefits over the traditional cluster made it more exciting to read.
CSV stands for Cluster Shared Volumes (CSV) is a feature of Failover Clustering first introduced in Windows Server 2008 R2 for use with the Hyper-V role. A Cluster Shared Volume is a shared disk containing an NTFS volume that is made accessible for read and write operations by all nodes within a Windows Server Failover Cluster.
In Windows Server 2012, its further improved and turned into a FULL BLOWN file system. Just like a standard file system, it is now compatible with filter driver (supports applications such as antivirus/backup etc.).
Going back to the main subject :
To understand how Cluster Shared Volumes (CSV) works in a failover cluster, it is helpful to review how a traditional cluster works without CSV. In a traditional cluster , a failover cluster allows a given disk (LUN) to be accessed by only one node at a time. Given this constraint, each Hyper-V virtual machine in the failover cluster requires its own set of LUNs in order to be migrated or fail over independently of other virtual machines. In this type of deployment, the number of LUNs must increase with the addition of each virtual machine, which makes management of LUNs and clustered virtual machines more complex.
In contrast, on a failover cluster that uses CSV, multiple virtual machines that are distributed across multiple cluster nodes can all access their Virtual Hard Disk (VHD) files at the same time, even if the VHD files are on a single disk (LUN) in the storage. The clustered virtual machines can all fail over independently of one another.
I am still reading some of these stuff and there are plenty already covered in various blogs and on Microsoft site. I guess, all I can do is provide some pointers to these reference material.
What is the role of SMB in Hyper-V Cluster based on CSV?
Cluster Shared Volumes operates by orchestrating metadata I/O operations between the nodes in the cluster via the Server Message Block protocol.
What is Coordinator Node ?
The node with 'ownership of the LUN' orchestrating metadata updates to the NTFS volume.
Advantage of CSV over traditional cluster comes during LIVE MIGRATION.
CSV reduces the potential disconnection period at the end of the migration since the NTFS file system does not have to be unmounted/mounted as is the case with a traditional cluster disk.
What is 'single name space' term used in CSV?
CSV builds a common global namespace across the cluster using NTFS reparse point. Volumes are accessible under the %SystemDrive%\ClusterStorage root directory from any node in the cluster.
How do I create CSV?
There is nothing different which needs to be done for CSV. CSV support iSCSI, Fibre Channel and Serial Attached SCSI (SAS) for storage. CSV will work with any of these, so long as the disk is using NTFS as the file system.
Benefits:
CSV will provide many benefits, including easier storage management, greater resiliency to failures, the ability to store many VMs on a single LUN and have them fail over individually, and most notably, CSV provides the infrastructure to support and enhance live migration of Hyper-V virtual machines.
With CSV, you can use live migration to move VMs from a Hyper-V host that needs maintenance to another Hyper-V host. Then when the maintenance is complete, you can move the VMs back to the original host—all with no interruption of end-user services. Live migration also enables you to build a dynamic datacenter that can respond to high resource-utilization periods by automatically moving VMs to hosts with greater capacities; thereby enabling a VM to meet Service Level Agreements and provide end users with high levels of performance, even during periods of heavy resource utilization.
Useful links:
http://blogs.msdn.com/b/clustering/archive/2009/02/19/9433146.aspx
Hyper-V R2 CSV FAQ:
http://en.community.dell.com/techcenter/virtualization/w/wiki/3021.aspx
http://windowsitpro.com/windows-server-2012/windows-server-2012-shared-storage-live-migration
http://technet.microsoft.com/en-us/library/jj612868.aspx
I touched base with Windows after a substantial gap, and that happened during the course of MCSE 2012 Server Infrastructure certification, I got introduced to various new features and technologies that were introduced in Server 2012, and one of which I liked the most is the improvement in CSV 2.0. The whole concept of CSV and it's benefits over the traditional cluster made it more exciting to read.
CSV stands for Cluster Shared Volumes (CSV) is a feature of Failover Clustering first introduced in Windows Server 2008 R2 for use with the Hyper-V role. A Cluster Shared Volume is a shared disk containing an NTFS volume that is made accessible for read and write operations by all nodes within a Windows Server Failover Cluster.
In Windows Server 2012, its further improved and turned into a FULL BLOWN file system. Just like a standard file system, it is now compatible with filter driver (supports applications such as antivirus/backup etc.).
Going back to the main subject :
To understand how Cluster Shared Volumes (CSV) works in a failover cluster, it is helpful to review how a traditional cluster works without CSV. In a traditional cluster , a failover cluster allows a given disk (LUN) to be accessed by only one node at a time. Given this constraint, each Hyper-V virtual machine in the failover cluster requires its own set of LUNs in order to be migrated or fail over independently of other virtual machines. In this type of deployment, the number of LUNs must increase with the addition of each virtual machine, which makes management of LUNs and clustered virtual machines more complex.
In contrast, on a failover cluster that uses CSV, multiple virtual machines that are distributed across multiple cluster nodes can all access their Virtual Hard Disk (VHD) files at the same time, even if the VHD files are on a single disk (LUN) in the storage. The clustered virtual machines can all fail over independently of one another.
I am still reading some of these stuff and there are plenty already covered in various blogs and on Microsoft site. I guess, all I can do is provide some pointers to these reference material.
What is the role of SMB in Hyper-V Cluster based on CSV?
Cluster Shared Volumes operates by orchestrating metadata I/O operations between the nodes in the cluster via the Server Message Block protocol.
What is Coordinator Node ?
The node with 'ownership of the LUN' orchestrating metadata updates to the NTFS volume.
Advantage of CSV over traditional cluster comes during LIVE MIGRATION.
CSV reduces the potential disconnection period at the end of the migration since the NTFS file system does not have to be unmounted/mounted as is the case with a traditional cluster disk.
What is 'single name space' term used in CSV?
CSV builds a common global namespace across the cluster using NTFS reparse point. Volumes are accessible under the %SystemDrive%\ClusterStorage root directory from any node in the cluster.
How do I create CSV?
There is nothing different which needs to be done for CSV. CSV support iSCSI, Fibre Channel and Serial Attached SCSI (SAS) for storage. CSV will work with any of these, so long as the disk is using NTFS as the file system.
Benefits:
CSV will provide many benefits, including easier storage management, greater resiliency to failures, the ability to store many VMs on a single LUN and have them fail over individually, and most notably, CSV provides the infrastructure to support and enhance live migration of Hyper-V virtual machines.
With CSV, you can use live migration to move VMs from a Hyper-V host that needs maintenance to another Hyper-V host. Then when the maintenance is complete, you can move the VMs back to the original host—all with no interruption of end-user services. Live migration also enables you to build a dynamic datacenter that can respond to high resource-utilization periods by automatically moving VMs to hosts with greater capacities; thereby enabling a VM to meet Service Level Agreements and provide end users with high levels of performance, even during periods of heavy resource utilization.
Useful links:
http://blogs.msdn.com/b/clustering/archive/2009/02/19/9433146.aspx
Hyper-V R2 CSV FAQ:
http://en.community.dell.com/techcenter/virtualization/w/wiki/3021.aspx
http://windowsitpro.com/windows-server-2012/windows-server-2012-shared-storage-live-migration
http://technet.microsoft.com/en-us/library/jj612868.aspx
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