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Determining which type of RAID to use when building a storage solution will largely depend on two things; capacity and performance. Performance is the topic of this post. We measure disk performance in IOPS or Input/Output per second. One read request or one write request = 1 IO. Each disk in you storage system can provide a certain amount of IO based off of the rotational speed, average latency and average seek time. I’ve listed some averages for each type of disk below. ...

VMware has lots of ways to setup networking on their ESXi hosts. In order to set this up in the best way for your needs, it’s important to understand how the traffic will be routed between VMs, virtual switches, physical switches and physical network adapters. Before looking at an example, we should review some networking 101. Machines on the same vlan on the same switch can communicate with one another (assuming there is no firewall type devices in the way). Machines on different vlans on the same switch cannot communicate unless the traffic passes through a router. ...

Zoning and Lun Masking are often confused for each other, probably because both of them are used to restrict access to storage. They should both be used to secure the storage network and reduce unnecessary traffic. Zoning If you want to specify only certain hosts from accessing a storage device then you would want to setup zoning. For instance, in the example below, you can see that the two servers on the right can access three of the four storage devices, whereas the two on the left can only access two of the SANs. This configuration is done on the Fibre Channel switch. iSCSI, NFS, and FCoE can also be segmented, but they would use typical TCPIP segmentation methods like setting up a VLAN. ...

It’s important to understand how VMware ESXi servers handle connections to their associated storage arrays. If we look specifically with fibre channel fabrics, we have several multipathing options to be considered. There are three path selection policy (PSP) plugins that VMware uses natively to determine the I/O channel that data will travel over to the storage device. Fixed Path Most Recently Used (MRU) Round Robin (RR) Let’s look at some examples of the three PSPs we’ve mentioned and how they behave. The definitions come from the vSphere 5 storage guide found below. ...

Emulation and Virtualization are not the same thing. In many cases you’ll hear them used interchangeably but they are different concepts. Emulation Emulation consists of taking the properties of one system and trying to reproduce it with a different type of system. When it comes to computers, you may have seen some software emulators that you can install and run on a PC or MAC, that will reproduce the characteristics of an older system such as a Nintendo or other gaming console. As an example you could then perhaps run Super Mario Bros. on your work desktop (I am not advocating the playing of video games at work). In this case the software emulator is mimicking the gaming console so that the game could be run inside the emulator, even though the underlying hardware is an x86 architecture. ...

Many storage providers have been working with VMware to improve performance of disks by giving VMware access to invoke capabilities of the storage system. There are basically three main primitives that VMware can invoke to do this. Full Copy Hardware Assisted Locking Block Zeroing Full Copy Lets look at what happens when you clone a VM without VAAI. The ESXi server will start to copy the blocks of the original VM and start to paste them in the new location. Below is an animation to describe this process. ...

vSphere has made it very simple to resize disks. They old days of finding larger disks to put in your severs and cloning or migrating data aren’t necessary now that virtualization has become widely used. If you’re using vSphere you can easily extend non system drives by changing the size of the Hard Disk, and then going into the virtual machine and using diskpart or Disk Manager and extending the drive. ...

I found people have a hard time understanding that a SAN Snapshot and a VMware snapshot are fundamentally different. I think because unless you’re a storage administrator, you’re probably not dealing a whole lot with snaps to begin with. VMware has made it more commonplace for System Administrators to deal with snapshot technology. SAN Snapshots Lets first look at how traditional SANs take snapshots. To start we have 6 blocks being used. The file system has marked blocks which blocks are being used. ...

I was recently tasked with performing a company wide disaster recovery test. The test had the normal goals with a standard recovery time objective, and recover point objectives. Unfortunately, the test needed to be performed during the middle of a production day, and not affect production. Under normal circumstances we could assume that our production servers were disabled or destroyed in some manner and we could power up our DR servers and continue the business. During this test however we needed to make sure that both networks could run at the same time. ...

VMworld 2011 was held at the Venetian Hotel in Las Vegas. Over 25,000 attendees this year. It was held in Las Vegas, but the sites and attractions didn’t take away from the event. Despite all the distractions that Las Vegas can provide, there was too much going on at VMworld to get caught up in the city. My favorite part of VMworld was the Hands on Labs. After signing up for the specific lab you wanted, you were ushered to your assigned desk. There were dual screen workstations setup at every desk and very straight forward instructions on how to complete the labs. These labs would get very in depth and would show you why and what was happening behind the scenes when you would perform your operations. I especially enjoyed the Netapp lab. ...