VCP-410 Q&A – Configure ESX/ESXi Storage (11-23)

Section 3 – Configure ESX/ESXi Storage

• Objective 3.2 – Configure iSCSI SAN Storage

QUESTION 11
How are new LUNs discovered by an ESX Host?
A.A rescan operation is required every time a new LUN is added
B.A reboot operation is required to detect newly presented LUNs
C.ESX Server automatically detects new LUNs as they are presented
D.ESX Server periodically performs a rescan operation to detect any new LUNs
Answer: A

Explanation:
iSCSI SAN Configuration Guide, page 26.
The VMkernel discovers LUNs when it boots, and those LUNs are then visible in the vSphere Client. If changes are made to the LUNs, you must rescan to see those changes.
New LUNs created on the iSCSI storage
Changes to LUN access control
Changes in connectivity

QUESTION 12
An ESX Server is configured to access an iSCSI target using CHAP authentication. What happens to the access if CHAP is disabled on the ESX Host?
A.Access is unaffected until the ESX Server is restarted
B.Access is removed on the next rescan
C.Access is unaffected until either the ESX Server or the iSCSI Array are restarted
D.Access is immediately removed
Answer: C
Explanation:
iSCSI SAN Configuration Guide, page 40.
If you disable CHAP on a system that requires CHAP authentication, existing iSCSI sessions remain active until you reboot your ESX/ESXi host or the storage system forces a logout. After the session ends, you can no longer connect to targets that require CHAP.

QUESTION 13
Using Hardware iSCSI Initiators with ESX/ESXi hosts allows which of the following tasks to be offloaded from the VMkernel (Choose Two)?
A.Encapsulation of iSCSI PDUs into TCP/IP packets
B.Encapsulation of I/O requests into iSCSI Protocol Data Units (PDUs)
C.Mapping requests for blocks on the virtual disk to blocks on the appropriate physical device
D.Issuing SCSI commands to the virtual disk
Answer: AB
Explanation:
iSCSI From Wikipedia, the free encyclopedia
An initiator functions as an iSCSI client. An initiator typically serves the same purpose to a computer as a SCSI bus adapter would, except that instead of physically cabling SCSI devices (like hard drives and tape changers), an iSCSI initiator sends SCSI commands over an IP network. An initiator falls into two broad types:
Software initiator
A software initiator uses code to implement iSCSI. Typically, this happens in a kernel-resident device driver that uses the existing network card (NIC) and network stack to emulate SCSI devices for a computer by speaking the iSCSI protocol. Software initiators are available for most mainstream operating systems, and this type is the most common mode of deploying iSCSI on computers.
Hardware initiator
A hardware initiator uses dedicated hardware, typically in combination with software (firmware) running on that hardware, to implement iSCSI. A hardware initiator mitigates the overhead of iSCSI [B above] and TCP [A above] processing and Ethernet interrupts, and therefore may improve the performance of servers that use iSCSI.

QUESTION 14
What is the maximum number of paths allowed in ESX 4.x for an iSCSI LUN?
A.8
B.4
C.2
D.16
Answer: A
Explanation:
Configuration Maximums VMware® vSphere 4.0 and vSphere 4.0 Update 1, page 4.
Table 2. Storage Maximums
Hardware iSCSI Initiators
Paths to a LUN 8

QUESTION 15
What is the default port used by iSCSI in a VMware vSphere environment?
A.2049
B.3260
C.902
D.443
Answer: B
Explanation:
VMware Consolidated Backup: Adding an iSCSI LUN to ESX Server
Unless you have changed the port that the iSCSI server runs on; port 3260 is fine, as it is the default iSCSI service port.

QUESTION 16
Which of the following components must be modified in order to enable Jumbo Frame support for the Software iSCSI Initiator (Choose Two)?
A.The virtual machine port group
B.The iSCSI vmhba
C.The virtual switch
D.The VMkernel port
Answer: CD
Explanation:
iSCSI SAN Configuration Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 30.
If needed, enable Jumbo Frames. Jumbo Frames must be enabled for each vSwitch through the vSphere CLI. Also, if you use an ESX host, you must create a VMkernel network interface enabled with Jumbo Frames.

QUESTION 17
Using Hardware iSCSI Initiators with ESX/ESXi hosts allows which of the following tasks to be offloaded from the VMkernel? Select all that apply-
A.Issuing SCSI commands to the virtual disk
B.Mapping requests for blocks on the virtual disk to blocks on the appropriate physical device
C.Encapsulation of iSCSI PDUs into TCP/IP packets
D.Encapsulation of I/O requests into iSCSI Protocol Data Units (PDUs)
Answer: CD
Explanation:
iSCSI SAN Configuration Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 19.
If the iSCSI initiator is a hardware iSCSI initiator (iSCSI HBA), the HBA performs the following tasks.
Encapsulates I/O requests into iSCSI Protocol Data Units (PDUs). [D above]
Encapsulates PDUs into TCP/IP packets. [C above]
Sends IP packets over Ethernet to the iSCSI storage system.

QUESTION 18
Which of the following CHAP Authentication mechanisms is available when using Software iSCSI, but not Hardware iSCSI? Select all that apply.
A.Per-Target CHAP
B.Per-Subnet CHAP
C.Mutual CHAP
D.One-way CHAP
Answer: AC
Explanation:
Software iSCSI support BOTH Per-Target and Mutual CHAP.
For Softare iSCSI only, you can set one-way CHAP and mutual CHAP for each initiator or at the target level.
Hardware iSCSI support CHAP only at the initiator level.
iSCSI SAN Configuration Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 37.
ESX/ESXi supports CHAP authentication at the adapter level. In this case, all targets receive the same CHAP name and secret from the iSCSI initiator. For software iSCSI, ESX/ESXi also supports per-target CHAP authentication, which allows you to configure different credentials for each target to achieve greater level of security.

QUESTION 19
Which of the following steps, required for iSCSI software multipathing, must be performed using the esx cli interface?
A.Binding the VMkernel ports to the selected uplinks
B.Configuring Dynamic Discovery for the iSCSI software initiator
C.Connecting the VMkernel ports to the virtual switch
D.Connecting the iSCSI software initiator to the VMkernel ports
Answer: D
Explanation:
iSCSI SAN Configuration Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 33.
Using the vSphere CLI, connect the software iSCSI initiator to the iSCSI VMkernel ports.
Repeat this command for each port. esxcli swiscsi nic add -n <port_name> -d <vmhba>

QUESTION 20
The Challenge Handshake Authentication Protocol (CHAP) is used with iSCSI on an ESX Server to provide which of the following?
A.Bi-directional Target authentication
B.Initiator authentication
C.LUN Group authentication
D.Storage Processor authentication
Answer: B
Explanation:
iSCSI SAN Configuration Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 37.
Because the IP networks that the iSCSI technology uses to connect to remote targets do not protect the data they transport, you must ensure security of the connection. iSCSI requires that all devices on the network implement Challenge Handshake Authentication Protocol (CHAP), which verifies the legitimacy of initiators that access targets on the network.

QUESTION 21
Which of the following statements are true about software iSCSI? (Choose Two)
A.It requires a dedicated NIC.
B.It is enabled by default.
C.CHAP authentication can be configured.
D.SendTargets can be configured.
Answer: CD
Explanation:
iSCSI SAN Configuration Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 35, 37.
Set up target discovery addresses so that the iSCSI initiator can determine which storage resource on the network is available for access.
The ESX/ESXi system supports these discovery methods:
Dynamic Discovery Also known as Send Targets discovery. Each time the initiator contacts a specified iSCSI server, the initiator sends the Send Targets request to the server. The server responds by supplying a list of available targets to the initiator. The names and IP addresses of these targets appear on the Static Discovery tab. If you remove a static target added by dynamic discovery, the target might be returned to the list the next time a rescan happens, the HBA is reset, or the host is rebooted.
Static Discovery The initiator does not have to perform any discovery. The initiator has a list of targets it can contact and uses their IP addresses and target names to communicate with them.
Because the IP networks that the iSCSI technology uses to connect to remote targets do not protect the data they transport, you must ensure security of the connection. iSCSI requires that all devices on the network implement Challenge Handshake Authentication Protocol (CHAP), which verifies the legitimacy of initiators that access targets on the network.
CHAP uses a three-way handshake algorithm to verify the identity of your host and, if applicable, of the iSCSI target when the host and target establish a connection. The verification is based on a predefined private value, or CHAP secret, that the initiator and target share.
ESX/ESXi supports CHAP authentication at the adapter level. In this case, all targets receive the same CHAP name and secret from the iSCSI initiator. For software iSCSI, ESX/ESXi also supports per-target CHAP authentication, which allows you to configure different credentials for each target to achieve greater level of security.

QUESTION 22
In ESX3, which of the following is a valid software iSCSI initiator?
A.vmhba2
B.vmnic1
C.vmhba32
D.iscsi0
Answer: C

QUESTION 23
Which two discovery options does the vSphere Client offer when setting up the iSCSI initiator? (Choose two.)
A.adaptive
B.non-selective
C.dynamic
D.selective
E.static
Answer: CE