How Does Virtualization Change Storage?May 18, 2009

Stephen Foskett, Director of Consulting, Nirvanix

Abstract

The virtualization of servers destroys everything that storage folks thought they knew about I/O and throws in a new layer of abstraction to boot

Creating storage for virtualization is not the same as storage for most other apps, and storage virtual servers on a SAN or NAS is not the same as using internal disk

This session will walk through what virtualization changes about storage, the various storage options, pros and cons, and what the future looks like with FCoE, UCS, 10 GbE, and VMware vStorage APIs

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Server Virtualization Recoil

The server virtualization revolution has challenged storage in many ways:Dramatically changed I/OImpact on storage capacity utilizationArchitecture decisions to be made: DAS, SAN, NASTrouble for traditional backup, replication, reporting

Biggest issue: Converged technology leads to converged management organizations

Pillars of Virtual Machine Performance

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Processor I/O (disk/net) Memory

Virtual machine performance demands a balanced base of processing, I/O subsystem, and memory

performance, capability, and capacity

Virtualization As An I/O Engine

Server virtualization is the single greatest I/O driver in the modern data center

CPU power and memory capacity are easy to ramp up, I/O is not

Unbalanced systems will not perform well

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I/O Is Concentrated

Then… Each server had its own

storage and LAN ports I/O utilization was low

Now…

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All I/O is concentrated on just a few ports

LAN SAN

LAN SAN

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I/O is Randomized

Then… Now… Sequential I/O is mixed

together randomly Disk is virtualized and re-

combined

I/O was mainly sequential Requests were grouped

physically on disk Storage could read ahead

and cache data

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I/O is Accelerated

Then… Now… Combined I/O Packets arrive quickly Quicker protocols: 10

GbE, 8 Gb FC

Channels were under-utilized with little contention for resources

Speeds were low: 1 GbE, IDE/ATA

1 GbE handles 1 packet from 1 host...4 Gb FC handles 4 packets from 4 hosts...8 Gb FC handles 8 packets from 5 hosts...10 GbE handles 10 packets from all 6 hosts...

In the same amount of time…

Converged Data Center I/O

Now… All I/O is concentrated on

just a few ports

Soon…

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I/O is converged on 10GbE and extended into server hardware

LAN SANLAN SAN

Server Virtualization and Storage Utilization

Wasted Space

Each level of abstraction adds overhead Overall utilization is low!

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Raw array capacity

Usable array capacity

LUNs presented to host

Configured datastore

Server 1 virtual disk

Server 1 used capacity

Server 2 virtual disk

Server 3 used capacity

Server 3 virtual disk

Server 3 used capacity

Thin Provisioning

Thin provisioning allocates storage as-needed Example: 500 GB request for new project, but only 2 GB

of initial data is written – array only allocates 2 GB and expands as data is written

What’s not to love? Oops – we provisioned a petabyte and ran out of storage Chunk sizes and formatting conflicts Can it thin unprovision? Can it replicate to and from thin provisioned volumes?

VMware adding thin provisioning to vSphere 4 (standard at all license levels!)

Some storage arrays do thin (3PAR, HDS, NetApp)12

Server Virtualization Demands SAN and NAS

Server virtualization has transformed the data center and storage requirements 86% have implemented some server virtualization (ESG

2008) VMware is the #1 driver of SAN adoption today! 60% of virtual server storage is on SAN or NAS (ESG

2008)

Server virtualization has enabled and demanded centralization and sharing of storage on arrays like never before!

VMware Storage Options:Shared Storage Shared storage - the common/

workstation approach Stores VMDK image in VMFS

datastores DAS or FC/iSCSI SAN Hyper-V VHD is similar

Why? Traditional, familiar, common (~90%) Prime features (Storage VMotion, etc) Multipathing, load balancing, failover*

But… Overhead of two storage stacks (5-

8%) Harder to leverage storage features Often shares storage LUN and queue Difficult storage management

VMHost

GuestOS

DAS or SANStorage

VMFS VMDK

VMware Storage Options:Shared Storage on NFS Shared storage on NFS – skip

VMFS and use NAS NTFS is the datastore

Wow! Simple – no SAN Multiple queues Flexible (on-the-fly changes) Simple snap and replicate* Enables full Vmotion Use fixed LACP for trunking

But… Less familiar (3.0+) CPU load questions Default limited to 8 NFS

datastores Will multi-VMDK snaps be

consistent?

VMHost

GuestOS

NFSStorage

VMDK

VMware Storage Options:Raw Device Mapping (RDM) Raw device mapping (RDM) -

guest VM’s access storage directly over iSCSI or FC VM’s can even boot from raw

devices Hyper-V pass-through LUN is

similar

Great! Per-server queues for performance Easier measurement The only method for clustering

But… Tricky VMotion and DRS No storage VMotion More management overhead Limited to 256 LUNs per data

center

VMHost

GuestOS

SAN Storage

Mapping File

I/O

Which VMware Storage Method Performs Best?

Mixed Random I/O CPU Cost Per I/O

Source: “Performance Characterization of VMFS and RDM Using a SAN”, VMware Inc., 2008

VMFS,RDM (p), or RDM (v)

Which Storage Protocol Performs Best?

Throughput by I/O Size CPU Cost Per I/O

Source: “Comparison of Storage Protocol Performance”, VMware Inc., 2008

Fibre Channel,NFS,iSCSI (sw),iSCSI (TOE)

And iSCSI is even better in vSphere 4!

How about Hyper-V?

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Which Storage Protocol is For You?

FC, iSCSI, NFS all work well Most production VM data is on FC Either/or? - 50% use a combination (ESG 2008)

Leverage what you have and are familiar with For IP storage

Use TOE cards/iSCSI HBAs Use a separate network or VLAN Is your switch backplane fast? No VM Cluster support with iSCSI*

For FC storage 4 Gb FC is awesome for VM’s Get NPIV (if you can)

FCoE is the future Converged storage and networks adapters (CNAs) Cisco UCS

Storage in VMware vSphere 4

Thin provisioning is standard for all levels

Dynamic expansion of VMFS volumes

Any-to-any Storage Vmotion

High performance I/O Paravirtualized SCSI Enhanced iSCSI stack Jumbo frames Data Protection APIs (A) Pluggable Storage

multipathing (E+)21

The Organizational Challenge

How will server, storage, and networking teams deal with integration?

Each discipline has its own best practices Each has its own prejudices They can be forced together, but will it work?

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Who Is Nirvanix

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2007 “Storage Products of the Year”2008 “Top Startups to Watch”2008 “Product of the Year”

The Premier “Cloud Storage” Service Provider for the Enterprise

Backed by Intel Capital, Mission Ventures, Valhalla Partners, Windward Ventures and European Founders Fund

Over 500 customers including leading Fortune 10, Media & Entertainment and Web 2.0 companies

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Thank You

NirvanixWe manage your storage,

so you can manage your business

www.nirvanix.com

twitter.com/nirvanix

Stephen Foskettsfoskett@nirvanix.com

Enterprise Storage Strategies Blog: bit.ly/ESSBlog

Personal Blog: blog.fosketts.net

Enterprise IT Content: gestaltit.com