Upgrading Your Skills to MCSA Windows Server 2012

Backup Operations in Hyper-V -
No VSS Writer Available?
In some cases, you need an Application-consistent backup but there is no VSS writer available. One example of this is MySQL. Hyper-V backups of virtual machines containing MySQL will always result in either a crash consistent or an image-level backup. For MySQL, the latter is probably acceptable as MySQL doesn't perpetually expand the log file. However, if you're using MySQL within a VSS-aware VM, then a Hyper-Vbased backup tool is going to take a crash- consistent backup. MySQL (like any other database system) isn't always recoverable from a crash-consistent backup; tool is going to take a crash-consistent backup. MySQL (like any other database system) isn't always recoverable from a crash-consistent backup; even when recovery is possible, it may be painful.
MySQL is just one example; any number of line-of-business Applications could tell a similar tale. In the case of MySQL, one solution is to find a guest-level backup
Application that is MySQL- aware and can back it up properly. For Applications for which no backup Application has a plug-in, you may need to have pre- and post-backup scripts that stop services or close Applications. If brief downtime is acceptable, you can disable the Backup item in Hyper-V Integration Services, thereby forcing Hyper-V to save the state of the VM during backup. This technique results in an image-level backup and can be used on any Application that doesn't have a VSS writer.

References:
https://www.altaro.com/hyper-v/vss-crash-consistent-vs-application-consistent-vss-backups-post-2-of-2/ I

Relative ID (RID) Master:
Allocates active and standby RID pools to replica domain controllers in the same domain (corp.contoso.com) Must be online for newly promoted domain controllers to obtain a local RID pool that is required to advertise or when existing domain controllers have to update their current or standby RID pool allocation.
The RID master is responsible for processing RID pool requests from all domain controllers in a particular domain. When a DC creates a security principal object such as a user or group, it attaches a unique Security ID (SID) to the object.
This SID consists of a domain SID (the same for all SIDs created in a domain), and a relative ID (RID) that is unique for each security principal SID created in a domain. Each DC in a domain is allocated a pool of RIDs that it is allowed to assign to the security principals it creates. When a DC's allocated RID pool falls below a threshold, that DC issues a request for additional RIDs to the domain's RID master. The domain RID master responds to the request by retrieving RIDs from the domain's unallocated RID pool and assigns them to the pool of the requesting DC.
At any one time, there can be only one domain controller acting as the RID master in the domain.


The Infrastructure Master -
-The purpose of this role is to ensure that cross-domain object references are correctly handled. For example, if you add a user from one domain to a security group from a different domain, the Infrastructure Master makes sure this is done properly.
As you can guess however, if your Active Directory deployment has only a single domain, then the Infrastructure Master role does no work at all, and even in a multi-domain environment it is rarely used except when complex user administration tasks are performed, so the machine holding this role doesn't need to have much horsepower at all.
References:
http://support.microsoft.com/kb/223346
http://en.wikipedia.org/wiki/Flexible_single_master_operation D