Data Storage Concepts

  Data Center Virtualization, VMWare

Shared Storage

  • Multiple computers access data on the same storage device
  • In the virtual world, shared storage means VMs
  • Most vCenter features require this.

vCenter features that REQUIRE shared storage

  • DRS
  • DPM
  • Storage DRS
  • High Availability
  • Fault Tolerance

Shared Storage Supported Formats

  • Fibre Channel
  • Fibre Channel over Ethernet (FCoE)
  • iSCSI
  • NFS
  • Local Storage

Fibre Channel

  • Fibre Channel is a high speed network technology generally used for network storage.
  • Generally speeds are 2, 4, 8 and 16 Gbps
  • It used FCP (Fibre Channel Protocol) similar to TCP
  • Often used for SAN (Storage Area Networks)
  • Despite its name, it does NOT require fibre, but can run on an electrical interface.  (This is why is uses the British spelling!)
Fibre Channel Topologies

Fibre_Channel-Topologies

Fibre Channel over Ethernet

  • Specification that allows sending FCP over standard Ethernet.
  • Generally ran on 10Gbps networks to maintain speed

Storage_FCoE

 

iSCSI (Internet Small Computer Interface)

  • IP Based protocol for linking network based storage facilities. (Protocol sends SCSI commands)
  • Can be used with LANS, WANS and Internet.
  • Can be used with standard Ethernet technologies
  • Requires no dedicated cabling
  • Performance can be affected by competition for networking resources

Terminology

  • Initiator: The server that acts as the client and communicates with the storage device.  Other PCs will connect to the initiator.
  • Target: The storage device

NFS (Network File System)

  • Standard networking protocol to mount a remote partition as if it was a local drive.

vSphere Storage Appliance (VSA)

  • Allows creation of shared storage from the local storage devices in the ESXi hosts
  • Provides management and control to share these devices to take advantage of DRS, HA and Fault Tolerance
  • Designate disks within ESXi hosts and VSA does the rest.
  • Replicates data between ESXi hosts, so if one fails, another can take over.
  • Runs as a VM or simply a server on the host?

vFlash

  • Good for VMs requiring high speed storage access
  • Uses internal SSD drives to accelerate READ performance
  • vFlash operates like a read-cache
  • VM must be configured to use the vFlash storage

Datastores

  • Virtual Machines are stored in containers called “Datastores”
  • These are Logical Volumes that allow storage of ESXi host and VMs
  • 2 types of Datastores
    • Virtual Machine File System (VMFS): Local, iSCSI, Fibre Channel, FCoE
    • Network File System (NFS): Network Attached Storage (NAS)

 

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