Objective 2.3 – Define Logical Storage Design
March 15, 2011 
Sean Crookston 
Knowledge
- List relevant storage technologies.
- Recall key features and functionality of relevant storage technology (fibre channel, NAS, iSCSI).
Skills and Abilities
Describe storage technology integration with the VMware vStorage APIs for Array Integration (VAAI).
Given a set of storage requirements, design an appropriate storage solution. Solutions may include, but are not limited to:
- Multipathing
- Availability
- Load balancing across storage processors
- Upstream/downstream service dependencies
Based upon multi-site and multi-application requirements (in addition to core infrastructure requirements), derive key attributes of appropriate storage solutions.
Define local storage design.
Tools
- ESX Configuration Guide
- ESXi Configuration Guide
- Fibre Channel SAN Configuration Guide
- iSCSI SAN Configuration Guide
- What’s New in VMware vSphere 4.1 – Storage
- Product Documentation
This objective focuses on defining the logical storage design. You could use local storage for a lab or maybe a smaller environment, however for purposes of discussion in this document we will focus on shared storage for virtual machine storage.
Local storage of course still comes in to play as ESX(i) needs somewhere to operate. You have options between boot from SAN, or local storage. Local storage could consist of local hard disks or the use of ESXi embedded.
When we look at deciding on a logical design for the shared storage we want to take the same precautions towards redundancy and high availability that we would with our virtual infrastructure. Storage support and capabilities have continued to grow with the release of vSphere 4.1 bringing several new features to the table.
Storage I/O Control allows the prioritization of VMs in an ESX cluster. It uses the concepts of shares and limits to control resources for block based storage when that storage device has exceeded a certain latency level device wide. During this time of contention more important workloads can be given priority for I/O queue slots. This default threshold is 30ms and can be modified per datastore. By default SIOC Is not enabled. It is important to note that in addition to the datastore needing to be on block based storage it must also reside on a single extent and only be managed by one vCenter management server.
vStorage API for Array Integration or VAAI is a new set of API for storage partners to leverage. These new features allow the array to be leveraged for processing and copy functions and as result yield huge performance increases in operations like cloning and storage vMotions. The three features listed below are not enabled by default and storage will require certain levels of firmware to work.
The three features currently supported by VAAI are
- Full Copy- Allows array to make full copy w/o ESX reading/writing data
- Block Zeroing- Array can zero out large number of blocks when creating a VM
- Hardware-assisted locking- alternative method to locking for a VMFS file system that improves scalability or larger designs.
Another nice new feature is additional vCenter capabilities for NFS, for which the storage counters and performance metrics in vCenter now align better to those with block based storage.
And another really nice improvement is full support for 8Gb adapters, where formerly only 4 Gb was supported.
During the logical phase the following questions may come up, but I will hold off on the particulars of each until later on as it is covered by other areas of the blueprint.
- Active/Active vs Active/Passive vs ALUA?
- Are we going to be using one or a mixture of NFS, iSCSI, or Fibre Channel?
- If we are using iSCSI,will we be using software based or hardware based iSCSI?
- Do we want to boot from SAN?
- Do want our storage to be Tiered?
- What type of growth do we need to prepare for with our storage environment?
- How will we replicate or protect our data?
Tags: 
