Instead
of using a dedicated LUN for each VM (so that you could migrate them between
cluster nodes without taking down the other VMs on the same LUN) as in Windows
Server 2008, you had now the possibility to store multiple VMs on the same LUN
by converting it to CSV.
CSV is a
distributed file access solution that let multiple nodes in a cluster to access
the same file system simultaneously.
This
means that many VMs can share the same volume, while you can failover, live
migrate and move VMs without affecting the other virtual machines. This leads
to better utilization of your storage since you don’t have to place VMs on
separate disks, and the CSV’s are not depending in disk letters so you can scale
this configuration out, if you’d like.
What’s
the latest and greatest related to CSV 2.0:
·
Windows
Server 2012 has brought some changes to the architecture, so there’s now a new
NTFS compatible file system, which is called CSVFS. This means that
applications running on a CSV are able to discover this, and leverage this. But
still, the underlying file system is NTFS.
·
BitLocker Support is added to the list, which means you
can secure your CSVs on a remote location. The Cluster Name Object is used as
the identity to decryption and you should include this in every cluster
deployment you are doing, because the performance penalty are less than 1%.
·
Direct
I/O for data access which gives enhancements for virtual machine creation and
copy operations.
·
Support
for other roles than Virtual Machines. There’s an entirely new story around SMB
in Windows Server 2012, and CSV is also affected by this. You can now put a SMB
file share on top of your CSVs, which makes it easier to scale out your cluster
storage, to share a single CSV among several clusters, where they will access
their shares instead of volumes. Just a reminder: You can run Hyper-V virtual machines
from a SMB file share in Windows Server 2012. This requires that both the
server and the client is using SMB 3.0.
·
The
marriage to Active Directory has come to an end. External authentication
dependencies, which you would run into if you started your cluster without an
available AD is now removed. This gives us an easier setup of clusters, with
less trouble and dependencies.
·
File
backup by supporting requestors that’s running Windows Server 2008 R2 or 2012.
You can use application consistent and crash consistent VSS snapshots.
·
SMB support with multichannel and direct. CSV
traffic can now stream across multiple networks in the clusters and utilize the
performance in your NICs that supports RDMA.
·
Integration with storage spaces (new in
Windows Server 2012) so that you can leverage your cheap disks (just a bunch of
disks, JBOD) in a cluster environment
·
Maintenance by scanning and repairing
volumes with no downtime
Remember:
No cluster = no high availability.
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