Chapter 2: Storage Infrastructure Flashcards
How do virtual machines communicate with their virtual disks?
Using SCSI commands. These SCSI commands can also be encapsulated into other forms.
Describe the function of storage virtualization.
Storage virtualization refers to a logical abstraction of physical storage resources and capacities from virtual machines.
What kind of storage virtualization does ESXi provide?
ESXi provides host-level storage virtualization.
Describe a storage device / LUN.
Storage devices or LUNs are storage volumes that are presented to a host from a block storage system and are available to ESXi for formatting.
From the standpoint of a virtual machine, what does each virtual disk appear as?
Each virtual disk appears as if it were a SCSI drive connected to a SCSI controller.
What is the purpose of SCSI in regards to Fibre Channel (FC)?
Fibre Channel is a network storage protocol used on SANs. SCSI commands are encapsulated into Fibre Channel frames and used to direct storage.
What is the purpose of iSCSI?
Internet SCSI (iSCSI), is a SAN transport protocol that can use regular ethernet connections between ESXi hosts and storage systems.
What network components are required on ESXi hosts connect to a network using iSCSI?
Hosts will use hardware iSCSI adapters or software-based iSCSI initiators with regular network adapters.
What versions of NFS are supported by ESXi?
ESXi supports NFS versions 3 and 4.1.
In ESXi, when a datastore is deployed onto block storage devices, what file system is used?
Virtual Machine File System (VMFS).
What function of ESXi describes the following?
“A mapping file that contains metadata that resides in a VMFS datastore and acts as a proxy for a physical storage device”
A Raw Device Mapping (RDM).
What is the benefit of using a Raw Device Mapping (RDM)?
It allows for virtual machines to directly access physical storage.
When using Raw Device Mappings (RDM), how do virtual machines interact with their storage?
The VM configuration references the RDM, not the storage device. The RDM acts as a proxy between the VM and the physical storage.
What compatibility modes are supported by RDM?
There are 2 compatibility modes supported by RDM:
- Virtual compatibility mode: the RDM acts like a virtual disk file
- Physical compatibility mode: the RDM offers direct access to the SCSI device
What are the benefits of using virtual compatibility mode with RDMs?
Virtual compatibility mode allows for the same extra features that you would find with a regular virtual disk file. This includes virtual machine snapshots and the use of disk modes.
What are the benefits of using physical compatibility mode with RDMs?
Physical compatibility mode allows for more direct access to the SCSI device. This allows support for applications that require lower-level control.
Why would someone choose to use RDMs over regular virtual disks?
An administrator plans to use storage features that are inherent to the SAN itself such as:
- SAN management
- storage-based snapshots
- storage-based replication
Or for implementing Microsoft Cluster Server (MSCS)
What is the purpose of a vSAN?
By running a layer of distributed layer of software across hosts in a cluster, a vSAN can utilize local storage on each host as a single storage pool. This allows features that would normally be exclusive to dedicated shared storage.
Describe virtual volumes (vVols).
Virtual volumes are encapsulations of VM files, virtual disks, and their derivatives that are stored natively inside a storage system.
How are Virtual Volumes created?
Virtual volumes are not created manually. They are created automatically when you create, clone, or snapshot a VM.
How are are Virtual Volumes (vVols) different from regular storage management?
Regular storage management involves managing space from within datastores, vVols involve managing abstract storage objects that are handled by storage arrays. With vVols, each VM itself is a unit of storage management which can have storage policies applied to it rather than on the LUN or datastore.
What term describes the following?
“A framework that provides a single control panel across various data services and storage solutions.”
Storage Policy Based Management (SPBM).
What term describes the following?
“Software components that can be installed on ESXi hosts and can offer additional data services to virtual machines.”
I/O Filters.
Storage services such as replication, encryption, and caching are examples of what?
I/O Filters.
VMFS datastores can be created on what 4 types of storage devices?
Fiber Channel, iSCSI, FCoE, and local storage devices.
What versions of VMFS are supported by ESXi 7.0?
VMFS versions 5 & 6 for reading and writing.
A spanned VMFS datastore can support what types of homogenous storage devices?
512n, 512e, or 4Kn.
What is the block size that is supported by VMFS versions 5 & 6?
VMFS versions 5 & 6 support a 1 MB block size.
What is the purpose of a block size on a VMFS datastore?
The block size defines the maximum file size and amount of space a file occupies.
What types of datastores are supported for Storage vMotion?
Storage vMotion supports migration across VMFS, vSAN, and vVol datastores.
What partition type(s) are supported by VMFS version 5 & 6?
VMFS datastores support GUID Partition Table (GPT),
When a VMFS datastore is upgraded from version 3 to version 5, when does the conversion from an MBR, to a GPT partition take place.
Only once the partition grows beyond 2 TB. If the partition stays bellow this size, then it will remain as a Master Boot Record (MBR) type.
What security mechanisms are supported by NFS version 3 & 4.1?
NFS version 3 supports AUTH_SYS, version 4.1 supports AUTH_SYS and Kerberos authentication.
What encryption algorithms are supported by NFS version 4.1?
AES256-CTS-HMAC-SHA1-96 & AES128-CTS-HMAC-SHA1-96.
Which version(s) of NFS support multipathing?
Only version 4.1 of NFS supports multipathing through session trunking.
What locking mechanisms are supported by NFS versions 3 & 4.1?
NFS version 3 supports proprietary client-side locking, whereas version 4.1 supports server-side locking.
What features are supported by the version 3 of NFS, but not supported by NFS version 4.1?
The older version of NFS supports the following:
- Storage DRS
- Storage I/O Control
- Site Recovery Manager
How can datastores can converted from NFS version 3 to NFS version 4.1?
There are 2 main ways that a datastore can be migrated:
- Storage vMotion can be used to migrate virtual machines from NFS version 3 datastores to NFS version 4.1 datastores.
- In some cases, the NFS datastore can be unmounted and remounted as NFS version 4.1.
What type of datastore is created and manipulated out of band by a vSphere APIs for Storage Awareness Provider (VASA)?
vVol datastores.
Describe the function of VASA providers in regards to vVol datastores.
They map virtual disk objects and their derivatives directly to the VM on the storage system. These objects can include:
- Clones
- Snapshots
- Replicas
How do ESXi hosts access virtual volumes (vVols)?
Through an intermediate point in the data path called the protocol endpoint.
What function do protocol endpoints serve in regards to storage?
Protocol endpoints serve as gateways for I/O between ESXi hosts and the storage system.
What network storage protocols are supported by protocol endpoints?
Protocol endpoints support Fibre Channel, FCoE, iSCSI, or NFS.
What 3 types of virtual disks are supported by vSphere with Kubernetes?
Ephemeral, container images, and persistent volumes.
A vSphere pod requires ephemeral storage to support what types of Kubernetes objects?
Logs, emptyDir volumes, and ConfigMaps.
Why does Kubernetes require persistent storage?
Some Kubernetes workloads require persistent storage to store independently of the pod.
What is the purpose of a First Class Disk (FCD)?
To store persistent volume objects in vSphere with Kubernetes.
What term describes using an indirect means to connect NVMe storage to a host?
Fabric Transport (NVMe-oF).
What NVMe term is analogous to a storage device (LUN) in other storage arrays?
An NVMe namespace represents a storage volume.
Describe the requirements for NVMe over RDMA (RoCE Version 2).
NVME over RDMA supports the following:
- An NVMe storage array with NVMe over RDMA transport support
- A compatible ESXi host
- Ethernet switches supporting a lossless network
- A network adapter that supports RDMA over Converged Ethernet
- A software NVMe over RDMA adapter
- An NVMe controller
Describe the requirements for NVMe over Fibre Channel.
NVME over Fibre Channel requires the following:
- A Fibre Channel storage array that supports NVMe
- A compatible ESXi host
- A hardware NVMe adapter (a Fibre Channel HBA supporting NVMe)
- An NVMe controller
Describe the purpose of the High-Performance Plug-in (HPP)?
HPP is used to improve the performance of NVMe devices on an ESXi host.
In ESXi, how are NVMe-oF targets presented to users?
As iSCSI targets.
What is the default plug-in for local NVMe devices?
VMware Native Multipathing Plug-In (NMP).
What is the recommended Plug-In to use with NVMe-oF?
VMware High-Performance Plug-In.
Describe the the path selection schemes (PSS) used by HPP when selecting physical paths for I/O requests.
HPP Path Selection Schemes:
- FIXED: A static/designated path
- LB-RR: Using the round-robin algorithm
- LB-IOPS: path selected by the least number of outstanding I/Os
- LB-BYTES: path selected by the least number of outstanding bytes
- LB-Latency: path selected by considering the latency evaluation time and the sampling I/Os per path
Describe the differences between a Hybrid and All-Flash vSAN cluster.
Hybrid clusters use flash devices for the cache layer, while relying on magnetic disks for the storage capacity layer. All flash clusters use flash storage for both cache and storage capacity layers.
Hosts contributing their local storage to a vSAN are also required to contribute ___?
At least one device for cache.
Describe the function of a disk group in vSANs.
The drives contributed by a host in a vSAN cluster form one or more disk groups. Each of these disk groups contains a flash cache device and at least one capacity device.
What term describes the following?
“A vSAN characteristic that provides highly scalable management of snapshots and clones”
On-disk format.
Describe the function of a fault domain.
Fault domains are configured to protect against rack or chassis failures by preventing all copies of VM disk data from residing on the single rack or chassis.
Describe the function of Data at rest encryption.
This function of vSANs provides encryption of data that is not currently in transit and on which no processes are being done. When a drive is removed, the data is encrypted.