Section 3 – Configure ESX/ESXi Storage
- Objective 3.1 – Configure FC SAN Storage
What is the maximum HBA’s Supported on VMware vSphere 4 Host?
Configuration Maximums VMware® vSphere 4.0 and vSphere 4.0 Update 1, page 4
Table. Storage Maximums HBAs per host 8
What is the name of the globally unique identifier assigned to each Fibre Channel Port?
D.World Wide Name
Fibre Channel HBAs are available for all major open systems, computer architectures, and buses. Each HBA has a unique World Wide Name (WWN), which is similar to an
Ethernet MAC address in that it uses an Organizationally Unique Identifier (OUI) assigned by the IEEE
When writes from a virtual machine are delivered to a Fibre Channel Storage Array, which of the following actions is taken by the VMkernel (Choose Three)?
A.The file corresponding to the virtual machine is located on the VMFS datastore
B.The request for blocks on the virtual disk is mapped to blocks on the appropriate physical device
C.The modified I/O request is sent from the device driver to the physical HBA
D.The commands are forwarded by the virtual SCSI Controller
E.The I/O request is converted from binary data form to optical form
Fibre Channel SAN Configuration Guide ESX Server 3.5, ESX Server 3i version 3.5 VirtualCenter 2.5, page 40.
When a virtual machine interacts with a SAN, the following process takes place:
When the guest operating system in a virtual machine needs to read or write to SCSI disk, it issues SCSI commands to the virtual disk.
Device drivers in the virtual machine’s operating system communicate with the virtual SCSI controllers. VMware ESX Server supports two types of virtual SCSI controllers: BusLogic and LSILogic.
The virtual SCSI Controller forwards the command to the VMkernel.
Locates the file in the VMFS volume that corresponds to the guest virtual machine disk. Maps the requests for the blocks on the virtual disk to blocks on the appropriate physical device.
Sends the modified I/O request from the device driver in the VMkernel to the physical HBA (host HBA).
The host HBA:
Converts the request from its binary data form to the optical form required for transmission on the fibre optic cable.
Packages the request according to the rules of the FC protocol.
Transmits the request to the SAN.
Depending on which port the HBA uses to connect to the fabric, one of the SAN switches receives the request and routes it to the storage device that the host wants to access.
To prevent non-ESX Servers from seeing VMFS datastores, where should LUN masking be configured?
A.on the Fibre Channel Switch
B.on the ESX Host
C.on the non-ESX Hosts
D.on the SAN Storage Device
Fibre Channel SAN Configuration Guide ESX 4.0, ESXi 4.0, vCenter Server 4.0, page 44.
‘Configure LUN masking on your SAN’
An administrator is installing an ESX Host to boot from a SAN LUN. The storage array is an active/passive array. After configuring the boot LUN and installing ESX, the system does not boot properly. Which of the following could cause this issue?
A.The Storage Processor port specified in the BIOS configuration of the HBA is active
B.The LUN specified in the BIOS configuration of the HBA is passive
C.The LUN specified in the BIOS configuration of the HBA is active
D.The Storage Processor port specified in the BIOS configuration of the HBA is passive
VMware ESX Server SAN Configuration Guide, page 60.
When you boot from an active-passive storage array, the storage processor whose world wide name (WWN) is specified in the BIOS configuration of the HBA must be active. If the storage processor is passive, the QLogic adapter cannot support the boot process.
The Runtime Name for a Fibre Channel storage device is equivalent to?
A.The Universally Unique Identifier (UUID) to the device
B.The name of the current path to the device in vmhba:C:T:L format
C.The name of the first discovered path to the device in vmhba:C:T:L format
D.The Network Address Authority (NAA) name of the device
Fibre Channel SAN Configuration Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 53.
The name of the first path to the device. The runtime name is created by the host. The name is not a reliable identifier for the device, and is not persistent.
The runtime name has the following format:
vmhba# is the name of the storage adapter. The name refers to the physical adapter on the host, not to the SCSI controller used by the virtual machines.
C# is the storage channel number.
T# is the target number. Target numbering is decided by the host and might change if there is a change in the mappings of targets visible to the host. Targets that are shared by different hosts might not have the same target number.
L# is the LUN number that shows the position of the LUN within the target. The LUN number is provided by the storage system. If a target has only one LUN, the LUN number is always zero (0).
For example, vmhba1:C0:T3:L1 represents LUN1 on target 3 accessed through the storage adapter vmhba1 and channel 0.
An administrator is configuring an ESX Host with 2 Fibre Channel HBAs. The attached FC Storage Array has two active Storage Processor ports. No zoning is configured. Using Round Robin multipathing, how many paths are used to send data to a VMFS Datastore at any given time?
Fibre Channel SAN Configuration Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 25.
Round Robin (RR) Uses a path selection algorithm that rotates through all available paths enabling
load balancing across the paths.
Round-Robin Load Balancing VMware ESX Server 3.5, VMware ESX Server 3i version 3.5, VMware VirtualCenter 2.5, page 1
When one path from the ESX Server host to the SAN becomes unavailable, the host switches to another path. ESX Server hosts can also use multipathing for load balancing.
When to switch – Specify that the ESX Server host should attempt a path switch after a specified number of I/O blocks have been issued on a path or after a specified number of read or write commands have been issued on a path. If another path exists that meets the specified path policy for the target, the active path to the target is switched to the new path.
Since the active path is switched to a new path, it can be assumed that only a single path is ever used at any given time, (B above).
What are two functions of zoning in Fibre Channel Switches (Choose Two)?
A.Restrict connections on a storage array to ESX Hosts that utilize the array
B.Prevents non-ESX Hosts from possibly destroying VMFS data
C.Controls and isolates LUNs on a Fibre Channel Storage Array
D.Reduces the number of targets and LUNs presented by a Fibre Channel Storage Array
Fibre Channel SAN Configuration Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 53, page 15.
To restrict server access to storage arrays not allocated to that server, the SAN uses zoning. [A above] Typically, zones are created for each group of servers that access a shared group of storage devices and LUNs. Zones define which HBAs can connect to which SPs. Devices outside a zone are not visible to the devices inside the zone.
Since devices outside a zone are not visible to the devices inside the zone it would rrevents non-ESX Hosts from accessing and possibly destroying VMFS data. [B above]
When configuring a FC-SAN with ESX 4, which of the following are valid requirements and/or recommendations (Choose Two)?
A.Each LUN should contain only one VMFS datastore
B.Each LUN must present the same LUN ID number to all ESX/ESXi hosts
C.Virtual machine multipathing software should be used to perform I/O load balancing to individual LUNs
D.RDMs should not be used to access raw disks from previous ESX 2.5 or 3.x Hosts
iSCSI SAN Configuration Guide , page 44, 66.
LUNs must be presented to each HBA of each host with the same LUN ID number.
Place only one VMFS datastore on each LUN.
A virtual machine is using a Fibre Channel attached Raw Device Mapped (RDM) LUN. Which of the following applications used with the virtual machine would require the RDM to be in Physical Compatibility Mode (Choose Three)?
A.Physical Server to Virtual Machine Clustering
B.SAN Management Agents
C.Storage Array based Replication
D.SCSI-target based software
Setup for Failover Clustering and Microsoft Cluster Service ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 25.
Cluster Physical and Virtual Machines
A standby host cluster has specific hardware and software requirements.
Use RDMs in physical compatibility mode (pass-through RDM). You cannot use virtual disks or RDMs in virtual compatibility mode (non-pass-through RDM) for shared storage. [A is correct].
Physical compatibility mode allows the guest operating system to access the hardware directly. Physical compatibility is useful if you are using SAN-aware applications in the virtual machine. However, a virtual machine with the physical compatibility RDM cannot be cloned, made into a template, or migrated if the migration involves copying the disk.
Virtual compatibility allows the RDM to behave as if it were a virtual disk, so you can use such features as snapshotting, cloning, and so on. [Therefore E is incorrect] Recommended Detailed Material on RDM’s
Physical mode for the RDM specifies minimal SCSI virtualization of the mapped device, allowing the greatest flexibility for SAN management software. In physical mode, the VMkernel passes all SCSI commands to the device, with one exception: the REPORT LUNs command is virtualized, so that the VMkernel can isolate the LUN for the owning virtual machine. Otherwise, all physical characteristics of the underlying hardware are
exposed. Physical mode is useful to run SAN management agents [B above] or other SCSI target based software [D above] in the virtual machine.