File System Alignment in Virtual Environments


In speaking to my fellow Implementation Engineers and team leads, I’ve come to learn file system misalignment is a known issue in virtual environments and can cause performance issues for virtual machines.  A little research has provided an overview of the storage layers in a virtualized environment, details on the proper alignment of guest file systems, and a description of the performance impact misalignment can have on the virtual infrastructure. NetApp has produced a white paper that speaks to file system alignment in virtual environments: TR 3747, which I’ve reproduced below.

In any server virtualization environment using shared storage, there are different layers of storage involved for the VMs to access storage.  There are different ways shared storage can be presented for the hypervisor and also the different layers of storage involved.

VMware vSphere 4 has four ways of using shared storage for deploying virtual machines:

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Preparing for a data center site survey


Before we ever start installing hardware or configuring software, we’re going to be conducting site surveys.  Although preliminary surveys have already been done, we’ll be going a bit more in-depth to determine any last requirements for enterprise virtualization that are lacking.  Initially, my thoughts were centered on the important things, like existing servers, storage, and networking assets.  But a CISSP on our team created a document that goes much deeper and would catch more deficiencies that would impact a successful data center deployment.  I’ll highlight the items of the likely less-thought-about issues that could hamper us if not properly accounted for:

Power

Distribution points, availability (how much downtime per day/week/month), how often main-line power is interrupted, are there brown-outs or line-spikes? Load factors for UPS units and current load (can the current UPS handle the hardware?), rack-mounted or facility UPS, UPS run-time under load, UPS battery life-cycle and maintenance, back-up generators, rack power distribution unit types and available receptacles with at least two per rack, each connected to different UPSs/distribution points/circuits

HVAC and Facility Air Handling

Capacity of chillers vs. heat output of equipment, is HVAC on UPS? Are there portable chillers in use? Rack flow capacity, rack row layout to include hot/cold rows, humidity

Fire Suppression

Type and location of suppressant, maintenance checklists, potential fire hazards

Physical Security

Types of access controls on entrances to data center (cipher, key, biometric, etc.), presence of camaras and capability (thermal, IR, pan, tilt, zoom), is building continuously occupied? Do people work in the data center? Distance of building location from hazards (near airport, near water but at lower level, prominent location, near high-traffic area), who has physical access? Verify accountability and access controls, emergency lighting during power-outage

Rack Configuration

Used/free RU space, power/signal grounding of racks, quality of existing wiring for power, networking, KVM, are racks lockable? Heat load/power draw for currently installed equipment, raised floor and capacity of floor, rack stability and anchoring

And I can’t help but include some of the storage, networking, and server notes, as well.

Storage

Makes/models in use, drive configuration and capacity, IP info, volume names, hostnames, domains, DR sites, IOps, quotas, interface names, 3rd party OS and apps, MAC/IP iSCSI addresses, protocols

Networking

Makes/models in use, used capacity, 10Gbps capable, IOS versions, management capability (WhatsUp Gold, SolarWinds, CNA), WAN connectivity between sites, topology and protocols,  speed/latency, availability of fibre channel/fabric switching

Servers

Makes/models in use, hardware specs, 10Gbps capable, system performance baseline (CPU/memory/IO), OS versions, currently installed stand-alone ESX/ESXi, P2V viability, for virtual servers: ESX/ESXi version, location of .vmdk files, resource allocation/limits/reservations, ESX/ESXi performance baseline (CPU/memory/IO), attached storage details (LUNs, capacity, RAID levels, port assignments/WWNs), protocols supported, V2V viability

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Introducing Mike Brown…well, virtually.


Welcome to VirtuallyMikeBrown.  This is my place on the interwebs to track my experiences as a new Virtualization Implementation Engineer.  I’ve started a new job that is a huge step up for me from my every day Windows systems administration.  I love my chosen career in IT and I’m always looking for the next challenge.  I’m beginning my fourth year in IT and I’ve come a long way – discovering the fun in technology, meeting some great folks along the way, and getting paid to do a job I love.  It’s hard to ask for more.  This site will document my on-the-job experiences, thought-processes, and learning as I implement, as a member of a team, enterprise virtualization for a very large customer in one of the world’s most austere environments.  I hope you’ll join me as I document, learn, and have fun.

All the best,

Mike

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