Module 6 Lesson 1 Storage Concepts - VMware vSphere 4.1 Study Flash Cards

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Module 6 Lesson 1 Storage Concepts - VMware vSphere 4.1 Study Flash Cards
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2012-01-11 07:57:19
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Storage Concepts - VMware vSphere 4.1 Study Flash Cards
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  1. Storage Overview

    What are datastores?
    Datastores are logical containers, like file systems, that hide specifices of each storage device and provide a uniform model for storing virtual machine files, ISO images, virtual machine templates and floppy images.
  2. Storage Overview

    Depending on the type of storage technology used, what file system formats/datastore types can a datastore have?
    • 1. VMware vStorage VMFS
    • 2. Network File System (NFS)
  3. Storage Technology Overview

    Name and describe the 4 storage technologies supported by VMware ESX/ESXi hosts in the VMware vSphere environment.
    • 1. Local Attached Storage - Internal or external storage disks or arrays attached to the host through a direct connection.
    • 2. Fibre Channel Storage - A high-speed transport protocol used for storage area networks (SANs). Fibre Channel encapsulates SCSI commands, which are transmitted between Fibre Channel nodes.
    • 3. iSCSI storage - A SCSI transport protocol, enabling access to storage devices over standard TCP/IP networks. iSCSI maps SCSI block-oriented storage over TCP/IP.
    • 4. Network-Attached Storage (NAS) - Storage shared over standard TCP/IP networks at the file system level. NAS storage is used to hold NFS datastores.
  4. Datastores

    A VMFS datastore can not hold a raw device mapping (RDM). True or False?

    If False, Why?
    False. A VMFS datastore can also hold a raw device mapping (RDM), which is used to access raw data.
  5. Datastores

    A datastore can be a VMFS datastore or an NFS datastore. True or False?

    If False, Why?
    True.
  6. VMFS

    Define VMFS.
    VMFS is a clustered file system that allows multiple physical servers to read and write to the same storage device simultaneously and enables unique virtualization-based services ie... distributed services.
  7. VMFS

    VMFS does not allow multiple ESX/ESXi host to concurrently access shared virtual machine storage. True or False?

    If False, Why?
    False. VMFS is a clustered file system that allows multiple physical servers to read and write to the same shared storage device simultaneously.
  8. VMFS

    Name 5 VMFS characteristics concerning:
    1. Storage access
    2. Storage expansion
    3. Storage block and file size
    4. Storage addressing
    5. Storage locking
    • VMFS:
    • 1. Allows concurrent access
    • 2. Can be dynamically expanded
    • 3. Can use an 8MB block size - good for storing large virtual disk files up to 2TB in size.
    • 4. Uses subblock addressing - good for storing small files
    • 5. Provides on-disk, block-level locking
  9. VMFS

    The size of a VMFS datastore can be increased dynamically while virtual machines residing on the VMFS datastore are powered on and running. True or False?

    If False, Why?
    True.
  10. VMFS

    A VMFS datastore can be configured to use an 8MB block size, to supuport large, virtual disk files up to what size?
    Virtual disk files up to 2TB in size (2TB minus 512 bytes).

    • If the VMFS datastore has been formatted with:
    • 1MB block size, the maximum file size is 256GB
    • 2MB block size, the maximum file size is 512GB
    • 4MB block size, the maximum file size is 1TB
    • 8MB block size, the maximum file size is 2TB minus 512 bytes
  11. VMFS

    What does a VMFS datastore use to make efficient use of storage for small files?
    A VMFS datastore uses subblock addressing to make efficient use of storage for small files?
  12. VMFS

    What does VMFS provide to ensure that the same virtual machine is not powered on by multiple servers at the same time?
    VMFS provides block-level distributed locking to ensure that the same virtual machine is not powered on by multiple servers at the same time?
  13. VMFS

    On what SCSI-based storage devices can VMFS be deployed?
    VMFS can be deployed on the following SCSI-based storage devices:

    • Locally attaced storage
    • Fibre Channel Storage
    • iSCSI storage
  14. VMFS

    How does a virtual disk stored on a VMFS datastore appear to a virtual machine?
    A virtual disk stored on VMFS datastores always appears to the virtual machine as a mounted SCSI device. The virtual disk hides the physical storage layer from the virtual machine's operating system.
  15. NFS

    What is Network File System (NFS)?
    NFS is a protocol that provides for storage shared over the netowrk at the file system level.
  16. NFS

    What version of NFS does ESX/ESXi support?
    ESX/ESXi only supports NFS version 3 over TCP/IP.
  17. NFS

    What is Network Attached Storage (NAS) ?.
    NAS is a specialized storage device that connects to a network and can provice NFS file access services to ESX/ESXi hosts.
  18. NFS

    NFS datastores are treated like VMFS datastores. True or False?

    If False, Why?
    True. Like VMFS datastores, NFS datastores can hold virtual machine files, templates and ISO images.
  19. NFS

    ESX/ESXi hosts use the Network Lock Manager (NLM) protocol, which is a standard protocol used to support the file locking of NFS-mounted files. True or False?

    If False, Why?
    Fasle. VMware has its own locking protocol. NFS lock are implemented by creating lock files on the NFS server. Lock files are named .lck-<fileid>, where <fileid> is the value of the fileid field. When a lock file is created, an update is periodically sent to the lock file to inform other ESX/ESXi hosts that the lock is still active. The lock file updates generate small (84-byte) WRITE requests to the NFS server.
  20. RDM

    What is a Raw Device Mapping (RDM)?
    A RDM is a mapping file in a VMFS volume that acts as a proxy for a raw physical device/LUN.
  21. RDM

    When is a RDM recommended?
    An RDM is recommended when a virtual machine must interact with a real disk on the SAN. For example, when you make disk array snapshots, have a large amount of data that you do not want to move onto a virtual disk or you want to cluster a virtual machine with a physical machine using MSCS.
  22. vStorage Virtual Disk Thin Provisioning

    What does Thin Provisioning enable?
    Thin Provisioning enables virtual machines to use storage space as needed and allows users to optimally but safely use available storage space by employing overallocation.
  23. vStorage Virtual Disk Thin Provisioning

    Thin provisioning provides alarms and reports that track allocation versus current usage of storage capacity. True or False?

    If False, Why?
    True.
  24. Uses of Local and Shared Storage

    On what storage do most administrators install ESX/ESXi Installable?
    Local Storage.
  25. Uses of Local and Shared Storage

    Virtual machines can not be located on local storage. True or False?

    If False, Why?
    False. ESX/ESXi supports locating Virtual Machines on local storage. However, some features such as distributed services are not possible.
  26. Storage Device Naming Conventions


    On ESX/ESXi hosts, SCSI storage devices are identified in several ways. Name 3.


    • SCSI ID - The unique address of a SCSI device.
    • Canonical name - The Network Address Authority (NAA) ID is a unique LUN identifier, guaranteed to be unique acrosss reboots. In addition to NAA IDs devices can also be identified with mpx or t10 identifiers.
    • Runtime Name - Uses the convention vmhbaN:C:T:L. This name is not persistent through reboots
  27. Storage Device Naming Conventions


    Name the 3 types of Canonical name identifiers ESX/ESXi host use.
    • Network Address Authority ID (NAA).
    • T10
    • mpx
  28. Storage Device Naming Conventions

    T10 is another unique SCSI device identifier that always begins with the string "t10". True or False?

    If False, Why?
    True. T10 identifiers are assigned by IEFT subcommittees (such as the INCITS) to specific vendors.
  29. Storage Device Naming Conventions

    An mpx name SCSI identifier is globally unique and presistent across reboots. True or False?

    If False, Why?
    mpx is a VMware namespace that is used when no other valid namespace can be obtained from the LUN. An mpx name is not globally unique and is not persistent across reboots. Typically, only local devices use names starting with "mpx".
  30. Storage Device Naming Conventions

    Which of the following is not true about the Runtime name SCSI identifier:

    A. It is the name of the first path to the device.
    B. It is a reliable identifier for the device because it is persistent.
    C. The runtime name might change if you add HBAs to the ESX/ESXi host.
    D. The runtime name is created by the host.
    B.

    The Runtime name is not a reliable identifier for the device because it is not persistent.
    (this multiple choice question has been scrambled)
  31. Physical Storage Considerations

    Name the vSphere storage considerations that should be discussed/researched before implementing a vSphere environment.
    • LUN sizes
    • I/0 bandwidth requirements
    • Disk cache parameters, zoning and masking
    • Identical LUN Presentation to each ESX/ESXi host
    • Which mulipathing setting to use (active-active or active-passive) for your storage arrays.
    • What NFS settings to use.

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