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VCAP-DCA Study notes – 1.1 Implement and manage complex storage

Storage is an area where you can never know too much. For many infrastructures storage is the most likely cause of performance issues and a source of complexity and misconfiguration – especially given that many VI admins come from a server background (not storage) due to VMware’s server consolidation roots.

Knowledge

  • Identify RAID levels
  • Identify supported HBA types
  • Identify virtual disk format types

Skills and Abilities

  • Determine use cases for and configure VMware DirectPath I/O
  • Determine requirements for and configure NPIV
  • Determine appropriate RAID level for various Virtual Machine workloads
  • Apply VMware storage best practices
  • Understand use cases for Raw Device Mapping
  • Configure vCenter Server storage filters
  • Understand and apply VMFS resignaturing
  • Understand and apply LUN masking using PSA‐related commands
  • Analyze I/O workloads to determine storage performance requirements

Tools & learning resources

Identify RAID levels

Common RAID types: 0, 1, 5, 6, 10. Wikipedia do a good summary of the basic RAID types if you’re not familiar with them. Scott Lowe has a good article about RAID in storage arrays, as does Josh Townsend over at VMtoday.

The impact of RAID types will vary depending on your storage vendor and how they implement RAID. Netapp (which I’m most familiar with) using a proprietary RAID-DP which is like RAID-6 but without the performance penalties (so Netapp say).

Scott Lowe has a good article about RAID in storage arrays, as does Josh Townsend over at VMtoday.

Supported HBA types

This is a slightly odd exam topic – presumably we won’t be buying HBAs as part of the exam so what’s there to know? The best (only!) place to look for real world info is VMware’s HCL (which is now an online, searchable repository). Essentially it comes down to Fibre Channel or iSCSI HBAs.

Remember you can have a maximum of 8 HBAs or 16 HBA ports per ESX/ESXi server.You should not mix HBAs from different vendors in a single server. It can work but isn’t officially supported.

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