Information Technology Reference
In-Depth Information
Prior to everything, the migration requirements have to be established. The management,
the IT department, and the provider all have to see eye to eye about what the customer wants
and what is technically possible, not to mention the level of downtime allowed and the proper
scheduling of the migration. The migration can be done either online or offline. If the cur-
rent network infrastructure of an organization allows for a lot of data to be uploaded at an
acceptable rate, then online migration is the best method, but if there is too much data and
not enough time, offline migration is the best option. In offline migration, physical drives
containing the data to be migrated have to be shipped or delivered to the provider's location
to be uploaded there. On the other hand, if you are migrating your system from a virtual one
to a physical one such as when virtualized servers can no longer really keep up with server
requirements, even with more instances, then that would be a virtual to physical migration.
After all the migration, business operations can finally proceed using the new system.
Now the focus shifts to maintenance of the new system and keeping all processes going
at top condition, even perhaps to create better ones. This requires regular maintenance of
servers, even virtual ones. Maintenance often means downtime, so it has to be scheduled
accordingly. Fortunately, in virtualized environments, this does not have to be the case. It
can mean running at lesser capacity because of the reduced number of servers, but there
does not have to be real downtime where the service is not accessible at all.
Finally, you learned about virtual network components: the virtual switch, virtual
HBA, and virtual router. These are the virtual analogues to the physical switch, router,
and HBA, and they do exactly the same things with a few improvements, such as more
ports, prevention of loopbacks, and other security features. We also dug further into the
virtual CPU, which is just a time slice representation rather than actual CPU control. This
means that there is no guarantee of CPU usage, but each vCPU is given a time allocation
on the physical CPU. Finally, we discussed storage virtualization, how storage can be
pooled so that it can be shared and how the capacity can be further increased through the
use of clustered storage.
Chapter Essentials
Creating, Importing, and Exporting Templates and Virtual Machines
The creation of
virtual machines is central to a virtualized environment. We went into some detail on how
to create virtual machines from scratch, how to clone virtual machines, and how to take
snapshots, which also act as clones. Virtual machine templates are important because they
help to lessen the time to create multiple virtual machines of the same type.
Installing Guest Tools
Guest tools are applications that you install on the guest operating
systems to allow the virtual machine to support additional functions, such as making better
use of the GPU, allowing for shared storage, or dragging and dropping in the case of Type 2
hypervisors. The functions being provided by the guest tools depend entirely on the virtual-
ization provider.
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