This series of posts is to cover storage concepts and its configuration. Storage is one of the important features of configuring and managing your virtual environment. Storage options give the flexibility to set up your storage based on your cost, performance, and manageability requirements. Shared storage is useful for disaster recovery, high availability, and moving VMs from one host on another.
In pervious post of this series, we’ve discussed about iSCSI Storage, it’s components, iSCSI naming conventions, and iSCSI initiators. If you missed previous posts of virtual storage series, you can follow:
In this post, we’ll learn about setting up iSCSI adapters. iSCSI adapter can be set up either software or hardware before an ESXi host can work with a SAN.
Types of iSCSI adapters
There are two types of iSCSI adapters
- Software iSCSI adapter
- Hardware iSCSI adapter
- Independent hardware adapter
- Dependent hardware adapter
Software iSCSI adapter
In software iSCSI adapter, standard NICs are used to connect the ESXi host with the software iSCSI adapters to a remote iSCSI target on the IP network. For configuring software iSCSI adapter, VMKernel networking configurations are required.
Hardware iSCSI adapter
Hardware iSCSI adapter is further classified into two iSCSI adapters:
Independent iSCSI hardware adapter: is responsible for iSCSI and network processing and management from ESXi host. for this purpose, VMKernel networking configurations are not required.
Dependent iSCSI hardware adapter: relies on VMKernel networking and iSCSI configurations. For example, Broadcom 5709 NIC is a dependent iSCSI adapter; when installed it provides two components, a standard network adapter and an iSCSI engine, to the same port.
Network Configurations for iSCSI Storage
To access the iSCSI storage in your virtual environment, you’ll need to configure VMKernel networking, and the same port can also be used to access NFS/NAS storage. Depending on your virtual environment, networking setup can be different to access your iSCSI storage.
- If you have a small setup and have a single network adapter, then you will need a VMKernel port on a virtual switch.
- If you have more than one physical adapters for accessing iSCSI in a redundant environment, host-based multipathing will be used.
For best practices, iSCSI network traffic should be isolated from other network traffic. If it is not physically possible, VLANs can be used for this purpose.
Creating Datastores and Discovering iSCSI Targets
Based on your virtual environment and storage requirements, VMFS, NFS datastores can be created as repositories for virtual machines. iSCSI target can be created in Server 2012 R2 and due to limited home lab resource I did the same. iSCSI adapter discover storage resources on the network and determines which one is available for access.
The ESXi host supports two iSCSI target discovery methods:
- Static Discovery: The iSCSI initiator does not perform iSCSI target itself. The iSCSI initiator knows in advance about the iSCSI targets which will be contacted via their IP addresses and domain names to communicate with them.
- Dynamic Discovery: It is also called SendTargets discovery. Each time the iSCSI initiator contacts with a specified iSCSI server, and sends a SendTargets request to the server. The server then responds by providing the list of all available targets to the iSCSI initiator.
Figure: Thanks to VMware
We have discussed about iSCSI adapter, types of iSCSI adapters, and their network configuration requirements in this post. In next post, we’ll see configuration of software iSCSI adapter step by step. Many vExperts have already done excellent job by configuring and sharing such useful information, but as part of this series, I’ll also share this in my next post.
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