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INFO: NetApp iSCSI to VMware Virtual Infrastructure
iSCSI, the implementation of the SCSI protocol over internet packets, is one of the cheapest (if not the cheapest) forms of connectivity to an external storage. It is a form of transmitting data from host to storage, and back, over the IP network. It is cheap since putting up a fiber channel infrastructure will cost more. But nowadays almost every infrastructure already has fiber with 10gigabit connectivity.
iSCSI enables the transmission of SCSI commands over IP-encapsulated packets. This allows organizations to consolidate storage and gain better utilization, not to mention this is easier to manage and backup. The protocol gives hosts an "illusion" that the storage is directly or locally attached to while in reality it sits somewhere else.
The biggest implementation of iSCSI that I have seen so far is its use for disaster recovery (or DR) purposes. On the VMware infrastructure, iSCSI can be utilized where there is a need to share disks or LUNs. And it is easily implemented since most servers nowadays come with adequate number of network interfaces. And it is independent of any physical hardware as long as everything is connected via IP.
The same implementation of NetApp iSCSI is used in the virtual infrastructure that I administer. Everything works after having introduced the LUNs and assigning IP addresses. And it sticks to the notion of keeping everything simple so it is easier to manage. However, during my research of best practice(s) of VMware infrastructure with NetApp storage via iSCSI, a community post in the VMware forums and NetApp community suggested that the NetApp virtual storage console plugin for vSphere needs to be installed.
True enough when the VSC plugin was installed, its interface showed alerts on the screen. Below is a screenshot of what it looks like.
Apparently, although it works after configuration, the settings are not that optimal. It needs further tweaking and the VSC interface itself can tweak the settings for optimal multipath settings, optimal active-active configuration, failover settings, etc.
Correcting or applying the right settings to the current environment is easy. It all it takes is to right click the alert icon and select "Set Recommended Values..".
It will then ask which of the recommended values are applied. All the needed options are ticket by default. The interface also displays what settings it changes.
When the recommended values are applied, the interface immediately changes from "Alert!" to "Normal". But reboot is still required as shown on the Status where it says "Pending Reboot".
After rebooting the ESXi host, the optimal settings are applied. The VSC interface on the vSphere Client application window confirms this.
To ensure that the guest machines are not impacted by the change, it is recommended to put the ESXi host in maintenance mode. It is easy to do since vMotion is there to ensure no downtime is incurred. This is the same route I applied. It also allows you to immediately reboot after applying the resolutions suggested by the virtual storage console.
After applying the tweaks, you will notice faster access to the storage infrastructure from the guest machines. If you have a similar infrastructure, install the VSC plugin and the benefits pay off immediately.