Configuring vSphere Storage

Question 1

Define and describe what a datastore is.

Answer 1

A datastore is a logical storage unit that can use space on one or more physical storage devices.

Datastores are used to hold data such as VMs, VM templates, and ISO images

A datastore is a generic term for a container that holds files and objects. Datastores are logical containers, analogous to file systems, that hide the specifics of the underlying storage device and provide a uniform model for storing virtual machine files. A VM is stored as a set of files in its own directory or as a group of objects in a datastore

Question 2

What types of datastores does vSphere support?

Answer 2

VMFS - virtual machine file system
NFS - network file system
vSAN - virtual storage area network
vSphere Virtual Volumes

Question 3

What is Block-backed storage?

Answer 3

is a datastore access method that:
- Stores data as blocks (a sequence of bytes)
- Used on local storage
- Used on Storage Area Networks (SANs) and accessed through either iSCSI or Fibre Channel
- Used by VMFS, vSAN, and vSphere Virtual Volumes datastores

Question 4

What is File-backed storage?

Answer 4

is a datastore access method that:
- Stores data hierarchically in files and folders
- Used on network-attached storage (NAS)
- Used by NFS and vSphere Virtual Volumes datastores

Question 5

What are File-based datastores?

Answer 5

contents of the datastore are stored as files
- a VM consists of a set of files
- each VM has its own directory
- VMFS and NFS datastores hold files

In file-based datastores, a directory contains the VM’s files, such as the configuration file, one or more virtual disk files, swap files, and so on.

Question 6

What are Object-based datastores?

Answer 6

contents of the datastore as objects
- a VM consists of a set of data containers called objects
- vSAN and vSphere Virtual Volumes datastores hold objects

In an object-based datastore, each VM consists of a VM configuration object, one or more virtual disk objects, a swap space object, and so on. An object is a data container. Each object on the datastore includes data, some metadata, and a unique ID.

Question 7

Describe each of the storage technologies supported by vSphere

Answer 7

Direct-attached storage: Internal or external storage disks or arrays attached to the host through a direct connection instead of a network connection.
Fibre Channel (FC): A high-speed transport protocol used for SANs. Fibre Channel encapsulates SCSI commands, which are transmitted between Fibre Channel nodes. In general, a Fibre Channel node is a server, a storage system, or a tape drive. A Fibre Channel switch interconnects multiple nodes, forming the fabric in a Fibre Channel
network.
FCoE: The Fibre Channel traffic is encapsulated into Fibre Channel over Ethernet (FCoE) frames. These FCoE frames are converged with other types of traffic on the Ethernet network.
iSCSI: A SCSI transport protocol, providing access to storage devices and cabling over standard TCP/IP networks. iSCSI maps SCSI block-oriented storage over TCP/IP. Initiators, such as an iSCSI host bus adapter (HBA) in an ESXi host, send SCSI commands to targets, located in iSCSI storage systems.
NAS: Storage shared over standard TCP/IP networks at the file system level. NAS storage is used to hold NFS datastores. The NFS protocol does not support SCSI commands.
iSCSI, network-attached storage (NAS), and FCoE can run over high-speed networks providing increased storage performance levels and ensuring sufficient bandwidth. With sufficient bandwidth, multiple types of high-bandwidth protocol traffic can coexist on the same network

Question 8

How can datastores be configured in vSphere 8.0?

Answer 8

Depending on the type of storage that you use, datastores can be formatted with VMFS or NFS

Question 9

What storage features are supported by both VMFS5 and VMFS6?

Answer 9

— Concurrent access to shared storage
— Dynamic expansion
— On-disk locking

Question 10

What storage features are supported by VMFS6 and not VMFS5?

Answer 10

— 4K native storage devices
— Automatic space reclamation
— 128 hosts per datastore

Question 11

Describe VMFS (Virtual Machine File System).

Answer 11

VMFS is a clustered file system where multiple ESXi hosts can read and write to the same storage device simultaneously.

The size of a VMFS datastore can be increased dynamically when VMs residing on the VMFS datastore are powered on and running. A VMFS datastore efficiently stores both large and small files belonging to a VM. A VMFS datastore can support virtual disk files. A virtual disk
file has a maximum of 62 TB. A VMFS datastore uses sub-block addressing to make efficient use of storage for small files.

VMFS provides block-level distributed locking to ensure that the same VM is not powered on by multiple servers at the same time. If an ESXi host fails, the on-disk lock for each VM is released and VMs can be restarted on other ESXi hosts.

VMFS can be deployed on three kinds of SCSI-based storage devices:
- Direct-attached storage
- Fibre Channel storage
- iSCSI storage

Question 12

Describe NFS (Network File System).

Answer 12

A Network File System (NFS) is a file-sharing protocol that ESXi hosts use to communicate with a network-attached storage (NAS) device.

NFS datastores are treated like VMFS datastores because they can hold VM files, templates, and ISO images. In addition, like a VMFS datastore, an NFS volume allows the vSphere vMotion migration of VMs whose files reside on an NFS datastore. The NFS client built in to
ESXi uses NFS protocol versions 3 and 4.1 to communicate with the NAS or NFS servers.

Because NFS 3 and NFS 4.1 clients do not use the same locking protocol, you cannot use different NFS versions to mount the same datastore on multiple hosts. Accessing the same virtual disks from two incompatible clients might result in incorrect behavior and cause data corruption.

Question 13

Describe vSAN (Virtual Storage Area Network).

Answer 13

vSAN is a hypervisor-converged, software-defined storage solution for virtual environments that does not use traditional external storage.

By clustering host-attached solid-state drives (SSDs) and hard disk drives (HDDs), vSAN creates an aggregated datastore that is accessible to all the ESXi hosts in the vSAN cluster.

When vSAN is activated on a cluster, a single vSAN datastore is created. This datastore uses the storage components of each host in the cluster.

Question 14

Describe vSphere Virtual Volumes.

Answer 14

vSphere Virtual Volumes virtualizes SAN and NAS devices by abstracting physical hardware resources into logical pools of capacity.

vSphere Virtual Volumes provides several functionalities:
- Native representation of VMDKs on SAN/NAS: No LUNs or volume management
- Works with existing SAN/NAS systems
- A new control path for data operations at the VM and VMDK level
- Snapshots, replications, and other operations at the VM level on external storage
- Automates control of per-VM service levels by using storage policies
- Standard access to storage with the vSphere API for Storage Awareness protocol
endpoint
- Storage containers that span an entire array

Question 15

Describe RDM (Raw Device Mapping).

Answer 15

Raw device mapping (RDM) is a file stored in a VMFS volume that acts as a proxy for a raw physical device.

Question 16

What is Fibre Channel?

Answer 16

Fibre Channel is a protocol used for accessing storage devices across a network.

A Fibre Channel SAN is a specialized high-speed network that connects your hosts to highperformance storage devices.

The network uses the Fibre Channel protocol to transport SCSI traffic from VMs to the Fibre Channel SAN devices.

ESXi supports:
- 32 Gbps Fibre Channel
- Fibre Channel over Ethernet (FCoE)

Question 17

What are the components of an iSCSI SAN?

Answer 17

An iSCSI SAN consists of an iSCSI storage system, which contains one or more LUNs and one or more storage processors. Communication between the host and the storage array occurs over a TCP/IP network.

The ESXi host is configured with an iSCSI initiator. An initiator can be hardware-based, where the initiator is an iSCSI HBA. Or the initiator can be software-based, known as the iSCSI software initiator.

An initiator transmits SCSI commands over the IP network. A target receives SCSI commands from the IP network.

Question 18

What are the 3 types of iSCSI adapters?

Answer 18

Software iSCSI
Dependent HW iSCSI
Independent HW iSCSi

Question 19

Describe software iSCSI adapter/initiator

Answer 19

A software iSCSI initiator is VMware code built in to the VMkernel. Using the initiator, your host can connect to the iSCSI storage device through standard network adapters. The software iSCSI initiator handles iSCSI processing while communicating with the network
adapter. With the software iSCSI initiator, you can use iSCSI technology without purchasing specialized hardware.

Question 20

Describe dependent iSCSI adapter/initator

Answer 20

A dependent hardware iSCSI initiator, also known as an iSCSI host bus adapter, is a standard network adapter that includes the iSCSI offload function. To use this type of adapter, you must configure networking for the iSCSI traffic and bind the adapter to an appropriate VMkernel iSCSI port.

Question 21

Describe independent iSCSI adapter/initiator

Answer 21

An independent hardware iSCSI adapter handles all iSCSI and network processing and management for your ESXi host. In this case, a VMkernel iSCSI port is not required.

Question 22

What iSCSI target-discovery methods are supported by an ESXi host?

Answer 22

Static discovery: The initiator does not have to perform discovery. The initiator knows in advance all the targets that it will contact. It uses their IP addresses and domain names to communicate with them.

Dynamic discovery or SendTargets discovery: Each time the initiator contacts a specified iSCSI server, it sends the SendTargets 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 as static targets in the vSphere Client. You can remove a static target that is added by dynamic discovery. If you remove the target, the target might be returned to the list during the next rescan operation. The target might also be returned to the list if the HBA is reset or the host is rebooted.

Question 23

What do iSCSI initiators use for authentication?

Answer 23

CHAP

Question 24

What types of CHAP authentication are supported by ESXi?

Answer 24

Unidirectional
Bidirectional
per-target

Question 25

Describe VMFS datastore.

Answer 25

VMFS is a high-performance, cluster file system that serves as a repository for files such as VM files, VM templates and ISO images.

A VMFS datastore is optimized for storing and accessing large files, such as virtual disks and memory images of suspended VMs.

A VMFS datastore can have a maximum volume size of 64 TB.

Question 26

What are the 2 options for increasing a VMFS datastore?

Answer 26

Add an extent to the VMFS datastore: An extent is a partition on a LUN. You can add an extent to any VMFS datastore. The datastore can stretch over multiple extents, up to 32.

Expand the VMFS datastore: You expand the size of the VMFS datastore by expanding its underlying extent first.

Question 27

For multipathing with Fibre Channel or iSCSI, what selection policies are supported?

Answer 27

Fixed: The host always uses the preferred path to the disk when that path is available. If the host cannot access the disk through the preferred path, it tries the alternative paths. This policy is the default policy for active-active storage devices.

Most Recently Used: The host selects the first working path discovered at system boot time. When the path becomes unavailable, the host selects an alternative path. The host does not revert to the original path when that path becomes available. The Most Recently Used policy does not use the preferred path setting. This policy is the default policy for active-passive storage devices and is required for those devices.

Round Robin: In addition to path failover, this policy supports load balancing across the paths. By default, the latency mechanism is activated on the host. The mechanism considers I/O bandwidth and path latency to select an optimal path for I/O. When using the latency mechanism, the Round Robin policy can dynamically select the optimal path and achieve better load balancing results. Before using this policy, check with storage vendors to find out whether a Round Robin configuration is supported on their storage.

Question 28

What are the components of an NFS file system?

Answer 28

An NFS file system is on a NAS device that is called the NFS server.
The NFS server contains one or more directories that are shared with the ESXi host over a TCP/IP network. An ESXi host accesses the NFS server through a VMkernel port that is defined on a virtual switch.