You plan to deploy a distributed database application that runs on Windows Server 2008 R2. You need to design a storage strategy that meets the following requirements:
Allocates storage to servers as required
Isolates storage traffic from the existing network
Ensures that data is available if a single disk fails
Ensures that data is available if a single storage controller fails
What should you include in your design?
A.
An iSCSI disk storage subsystem that uses Microsoft Multipath I/O. Configure a RAID 0 array.
B.
An iSCSI disk storage subsystem that uses Virtual Disk Service (VDS). Configure a RAID 5 array.
C.
A Fibre Channel (FC) disk storage subsystem that uses Microsoft Multipath I/O. Configure a RAID 5
D.
A Fibre Channel (FC) disk storage subsystem that uses Virtual Disk Service (VDS). Configure a RAID 0 array.
Explanation:
MCITP Self-Paced Training Kit Exam 70-646 Windows Server Administration:Fiber channel with isolate the network,
Multipath I/O
Multipath I/O (MPIO) is a feature of Windows Server 2008 that allows a server to use multiple data paths to a storage device. This increases the availability of storage resources because it provides alternate paths from a server or cluster to a storage subsystem in the event of path failure. MPIO uses redundant physical path components (adapters, switches, cabling) to create separate paths between the server or cluster and the storage device. If one of the devices in these separate paths fails, an alternate path to the SAN device will be used, ensuring that the server is still able to access critical data. You configure failover times through the Microsoft iSCSI Software initiator driver or by modifying the Fibre Channel HBA driver parameter settings, depending on the SAN technology deployed in your environment.If the server will access a LUN through multiple Fibre Channel ports or multiple iSCSI initiator adapters, you must install MPIO on servers. You should verify that a server supports MPIO prior to enabling multiple iSCSI initiator adapters or multiple Fibre Channel ports for LUN access. If you do not do this, data loss is likely to occur. In the event that you are unsure whether a server supports MPIO, only enable a single iSCSI initiator adapter or Fibre Channel port on the server.
Windows Server 2008 MPIO supports iSCSI, Fibre Channel, and Serially Attached Storage (SAS) SAN connectivity by establishing multiple connections or sessions to the storage device. The Windows Server 2008 MPIO implementation includes a Device Specific Module (DSM) that works with storage devices that support the asymmetric logical unit access (ALUA) controller model as well as storage devices that use the Active/Active controller model. MPIO also supports the following load-balancing policies:
FailoverWhen this policy is implemented no load balancing is performed. The application specifies a primary path and a group of standby paths. The primary path is used for all device requests. The standby paths are only used in the event that the primary path fails. Standby paths are listed from most preferred path to least preferred path.
FailbackWhen this policy is configured, I/O is limited to a preferred path while that path is functioning. If the preferred path fails, I/O is directed to an alternate path. I/O will automatically switch back to the preferred path when that path returns to full functionality.
Round-robinAll available paths are used for I/O in a balanced fashion. If a path fails, I/O is redistributed among the remaining paths.
Round-robin with a subset of pathsWhen this policy is configured, a set of preferred paths is specified for I/O and a set of standby paths is specified for failover. The set of preferred paths will be used until all paths fail, at which point failover will occur to the standby path set. The preferred paths are used in a round-robin fashion.
Dynamic least queue depthI/O is directed to the path with the least number of outstanding requests.
Weighted pathEach path is assigned a weight. The path with the least weight is chosen for I/O.
Load-balancing policies are dependent on the controller model (ALUA or true Active/ Active) of the storage array attached to the Windows Server 2008 computer. MPIO is added to a Windows Server 2008 computer by using the Add Features item in the Features area of Server Manager.MORE INFO More on MPIO
To learn more about Multipath I/O, consult the following TechCenter article:http://www.microsoft.com/WindowsServer2003/technologies/storage/mpio/default.mspx.Striped with ParityThis LUN type, also known as RAID-5, offers fault tolerance and improved read performance, although write performance is hampered by parity calculation. This type requires a minimum of three disks and the equivalent of one disks worth of storage is lost to the storage of parity information across the disk set. This LUN type will retain data if one disk is lost, but all data will be lost if two disks in the array fail at the same time. In the event that one disk fails, it should be replaced as quickly as possible.