This document discusses how storage considerations are often overlooked when planning cloud applications. It introduces DataCore's role in providing storage virtualization software to help organizations tackle storage issues. Key aspects covered include establishing shared storage pools with different tiers to optimize performance and costs, using thin provisioning to efficiently allocate storage, and automated storage tiering to dynamically optimize workloads across different storage devices.

1. The Economics of Tiers in Virtual Storage Pools
There are numerous companies that help cloud-enable apps, servers
and networks. You’ve likely spent a fair amount of time strategizing
with a few of them. Yet, it’s been our experience that storage
considerations are often left for last; which inevitably leads to a mad
scramble wrestling the many difficult, disk-related matters that no one
had anticipated. We’d even go on to say that it is not at all uncommon
for these seemingly peripheral issues to be overlooked altogether
until they become a serious stumbling block in your rollout.
Fortunately, whether you’re in a panic, or early in your planning,
you’ll find the guidance below timely and actionable. You see,
DataCore, in partnership with our network of authorized solution
advisors, offers consultation in the specialized domain of storage
virtualization software – the state-of-the-art technology for tackling
storage-related matters in IT organizations large or small.
We’ve accumulated strong credentials across 20,000+
installations spread across the globe. An increasing percentage
of these aspire to host private clouds like you.
Cloud Reference Models
First, don’t be shocked at seeing the elaborate diagram (Figure 1)
conceived by the National Institute of Standards and Technology (NIST).
Think of it as the Reference Architecture for making a well-designed Cloud.
None of us pretend to be experts on these many service layers, but we
do have a real good handle on the modules in the center of the diagram.
The Storage Side of Private Clouds
Keeping it Light and Inexpensive
WHITE PAPER
Abstract
In the past 2 to 3 years, the storage
side of private clouds has been
weighed down by heavy iron, big
spending and a lot of complexity.
Throughout this white paper
you’ll get acquainted with recent
software developments and
practices which reshape storage
into a far more appealing and
inexpensive component of your
next generation IT environment.
Pressing Topics
• Contrast from typical data center
• Customer examples
• Where to get started
• Measuring success
• Transition Guidelines
• Resource Sharing & Provisioning
• Service Levels
• Automation
• Resiliency
• Change Management
• Portability

2. 2
These incorporate those aspects of
IaaS or Infrastructure as a Service, as
well as the adjacent modules charged
with abstracting and controlling the
storage resources underneath. More
specifically, they help you establish
how systems should be configured and
provisioned; what steps you can take to
ensure portability and interoperability;
doing so while shielding the surrounding
layers from the inescapable problems
which hardware resources and the
facilities housing them can cause you.
They may even prepare you to take on
those wild curve balls that the business
throws your way. Let’s start slicing this
down into more digestible concepts.
Not Your Typical Data Center
Analysts, such as Gartner, distinguish
private Clouds from conventional
IT practices using a few criteria:
Clouds offer consumers a self-service
interface using Internet technologies.
Resources are no longer purchased
or assigned permanently to a project.
Rather, the assets are pooled and each
consumer’s resource consumption
is metered in order to calculate
cost allocations. Be that purely for
internal budgeting purposes or actual
internal billing. In this regard, it is
quite similar to a public cloud.
The provider, namely you, is responsible
for hosting a scalable, shared and,
ideally, an automated infrastructure
that can stretch and shrink to fulfill user
demands. We’ll cover how such elasticity
is achieved in a second. Effectively,
the consumer remains unaware of
the cloud’s internal workings.They
simply input processing requirements
and get back their results from the
black box. How quickly those results
come back depends heavily on the
conduct of the storage infrastructure.
Drivers for Private Cloud
Understand that business agility,
sometimes defined as the speed with
which you can respond to the processing
needs of the company, is the number one
reason driving many of your colleagues
to pursue a private cloud initiative
(Figure 3). A smaller minority is headed
there because they hope to lower costs
over the long haul. Still others would
prefer to use a public cloud and unload
their IT responsibilities altogether,
but have determined that the public
route does not adequately meet their
service level, regulatory or legal needs.
Therefore, they have to take ownership.
We bring this up because it has much
to do with setting expectations.
There may be a handful of you
thinking that this private cloud stuff is
beyond your reach. But the principles
discussed below still apply to you.
In fact, they’ll help you evaluate
outsourcing candidates, should you
choose to hire out the transition.
We’ve also run into smaller educational
institutions and municipalities such
as Saginaw Intermediate School
District who’ve banded together to
achieve critical mass where a collective
private cloud makes perfect sense.
Fig.1-NISTCloudReferenceModelwithDataCore’srole highlighted
Source: National Institute of Standards and Technology
Source: GartnerFig.2-Privatecloudcharacteristics

3. Throughout the rest of this whitepaper
we will get a bit more technical with
hands-on tips, beginning with the
subject of Resource Sharing.
Resource Sharing
In cloud lingo, sharing and pooling are
nearly synonymous. Rather than isolate
IT assets like disks and SANs into specific
programs or projects, as has been the
norm in years past, one establishes
a shared resource pool from which
different consumers draw capacity.
The pool consists of multiple
storage tiers, each well suited to
meet different reliability, quality of
service or performance objectives.
The pool amortizes the cost of the
underlying infrastructure across many
consumers. It also absorbs the peaks
and valleys generated by variable user
workloads. Sharing is a good thing!
Recall the abstraction layer we
introduced a couple of pages back? It
plays a big part in how space is shared,
and is a central feature of virtualization.
Recognize that what subscribers ask for
and what they actually consume can vary
greatly. Most apps overestimate their
future disk needs.They make bloated
requests for very large volumes that
in practice go heavily underutilized.
“Thin-provisioning” techniques built
into storage virtualization software
deal with the mismatch very well.
Thin Provisioning
In essence, the software doles out small
chunks of capacity just-in-time to the
consumer, and does so without tying
up all the space they initially requested;
In other words, no huge pre-allocation
of disks. Still, the app‘s needs are
satisfied while the organization saves
lots of money. Of course, DataCore’s
thin provisioning software takes care
to notify you well before the existing
disk space becomes exhausted to
make absolutely sure that you expand
capacity ahead of depletion.
No Downtime to
Expand or Migrate
If you think that’s cool, here is another
beauty. No downtime is necessary to add
new drives into the virtual pool.The new
disks could be from different suppliers, if
you can manage a better bargain, since
no backward compatibility is required.
With resource sharing we mentioned
tiers.These classes of storage, be they
high, medium, or low, map directly into
cloud service levels and SLAs. However,
those tiers are applied very differently
in the cloud than the static assignments
that you may be forced into today.
Have a look at the graphic to the
left. During the course of running
an app, certain execution segments
require different types of storage.
Portions of the program, say SQL
Server or Oracle, may require fast,
top-of-the-line, Fibre Channel disks
or possibly solid state drives during
its heavy data-input cycle. Whereas
the bulk of intermediate calculations
will do fine using basic, reliable space
on real inexpensive disk drives.
Source: GartnerFig.3- Driversforprivatecloud
3
Fig.4-Variablestoragerequirementsfromwithinthe sameapp

4. Allocating SSDs exclusively to the
database would be a costly mistake.
And it would tie up those valuable
resources, while keeping other
applications from getting to them.
Who could possibly juggle all those
decisions in real time? Clearly not a job
for even the most adroit carbon robots.
No, the magic is in a recent development
known as automated storage tiering.
The system administrator need only set
the global policy for the circumstances
that merit premium vs. inexpensive
storage or anything in between, and
then hands it off to the software to take
care of the rest. Needless to say, you
can still define extraordinary workloads
that absolutely must have the speediest,
most bullet proof assets; particularly for
apps like general ledger reconciliation
run during specific crucial windows.
But by and large, the majority of
workloads are dealt with automatically.
Such dynamic optimization of
diverse resources, especially toggling
between equipment from different
suppliers, is on the leading edge of
21st century cloud technologies.
What seems like exceptionally
well-running apps to the user is
largely a product of a well-balanced
arsenal of purpose-built devices
orchestrated by DataCore’s storage
hypervisor. Combined with thin
provisioning, they translate into
major savings and big time agility.
As Figure 5 shows, distribution wise,
we’ve found the median for fast SSD
and Flash cards accounting for around
5% of the pool’s capacity. Somewhere
in the 35 to 45% carved out from
high-speed SAS and Fibre Channel
drives. And the balance made up of
high-density, inexpensive SATA drives.
Hybrid Clouds
Interestingly, some of our customers
occasionally tap into public cloud
storage for short term extension to their
private cloud capacity. Which brings
us to hybrid clouds.That’s where you
auto tier between your on-premises
privately owned assets and off-site
rented disks, usually obtained from
one of the commercial Cloud providers
like Amazon, AT&T and several others.
The extra buffer comes in real handy
when you need a little scratch space,
or when you archive documents that
don’t warrant the same security or
regulatory oversight as other volumes.
It’s also a great option for storing
contents that may need to be recovered
after a disaster; more on that in a
minute. But first we should address all
the standardization talk going around.
Interchangeability
You may have noticed how tight knit
groups of vendors are allying to dictate
building blocks for private clouds, always
under the guise of “standardization.”
Each vendor club has a different recipe
calling out their hardware/software
combination.Their message implies
that choosing components outside the
member companies could jeopardize
your installation because the pieces
haven’t been pre-integrated.
In stark contrast, DataCore’s stance
on standardization enables complete
interchangeability; giving you the
freedom to harness the best purpose-
built equipment for each tier in the
cloud, regardless of which fraternity
is most popular at the time. We let
you shop for the best value among
competing hardware suppliers – all of
which have a suitable lineup of products.
It’s more a question of who may
be more willing to earn your
business next go-around.
Key to making this work is sticking
to established disk interfaces, and
treating storage as no more than largely
interchangeable buckets of disk space, to
be replaced when their useful life expires
and something else takes its place.
Caching
There is another less visible technology
at play here that figures into the high-
performance response keeping users
smiling. We call it adaptive caching.
Our caching techniques have been
perfected over the past decade.
They effectively maintain frequently
accessed data in electronic memory
4
Fig.5-TieredstorageacrossresourcesacrossHybridCloud

5. so they can be accessed much quicker
than waiting on the mechanical disk.
Similar methods are used in internet
caches to accelerate your web browsing
experience. Adaptive caching boosts the
performance of disk updates beyond
the native speed of storage devices.
Besides the enhanced app response,
this clever approach takes cost out
of the infrastructure. It allows you to
employ less expensive disk technology
in the pool and get faster results from
equipment already on the floor.You
know- more bang for the buck.
APIs
What about those Cloud APIs you’ve read
about? It turns out that many of those
application programming interfaces
are not so relevant when automation
is making decisions on your behalf.
Having said that, upper level layers
must expose service catalogs to
advertise what consumers can and can’t
do. But those actions typically occur
above the IaaS stratum in the form
of a user-friendly menu selection.
Circumventing Outages
Before going any further, what do you
say we spend a few minutes dealing
with mayhem?Yes, all the crazy
upheaval that follows disks around like
a plague. On the positive side, storage
manufacturers do a fantastic job of
improving hardware reliability every
year. But the construction crews outside
your datacenters seem less concerned.
Much of the unplanned downtime
these days has to do with facility
problems; electrical, air conditioning,
technician errors, leaky faucets, to
name a few. Emulate what professional
hosters do and you’ll be just fine. It’s
all about building redundancy and
creating a little distance between
your data and harm’s way.
If you ask us, keep two copies of critical
data updated in separate rooms.
Never share the same power, HVAC or
plumbing. OK, so sharing is not always
good.The rooms can be a few feet apart
or up to 100 kilometers away. Beyond
that, distance-related delays start to
appreciably slow down response to
the point where users complain.
Part of what’s neat about the DataCore
software is how it presents these two
copies to the apps as a single coherent
virtual disk so they don’t have to do
anything special. In the background
the SANsymphony™-V storage
hypervisor automatically keeps the
two copies synched up, transparently
switching between them if one side is
taken out-of-service. We use device-
independent synchronous mirroring
over a campus SAN or low-latency
metropolitan area network to keep
the redundant images in lockstep.
This way, when the A/C unit keels over
in building 1 and the room starts to heat
up and drives begin to shut down, the
app is quickly re-directed to the copy in
Building 2 without a glitch. Meanwhile,
the site problems can be addressed
unbeknownst to the subscribers, and
the entire environment can be restored
and resynchronized in the background
once the temperature is back to normal.
Worry-free Change
Management
In addition to shielding your subscribers
from unexpected environmental and
facility issues, redundancy plays a big
role in eliminating planned downtime.
These scheduled events don’t usually get
included in the way IT counts outages,
but the private cloud consumers sure do.
The secondary benefits of architecting
for resiliency with DataCore is that
you also achieve worry-free, non-
disruptive, change management.Your
team can repair, replace, upgrade and
decommission storage and storage
networks without having to schedule
downtime. And it can take place
whenever you deem convenient-
preferably during normal working
hours. So your staff, and you, can spend
holidays somewhere other than the
computer room trying to complete
a frantic disk migration. From the
consumers’ standpoint, everything
is working well in their Cloud.
To put it in perspective, the prestigious
NY Presbyterian Hospital relocated
half their datacenter from NewYork
to New Jersey without taking down
users.Thanks in large part to DataCore.
Their hot-hot sites are now split across
the river separating the two states.
5
Regional Data Centers Disaster Recovery Site
Fig.6- Replicationtoensure resiliency

6. Mitigating Disasters
The second phase of your business
continuity plan must incorporate
more robust disaster avoidance using
a faraway location.The objective
is to safeguard the consumer’s
information from regional threats or
catastrophes that can affect entire
metropolitan areas. I’m talking floods,
power grid failures, earthquakes,
hurricanes, and other acts of God.
The two real-time copies housed
within 100 kilometers from each other
may not do you much good here.
A 3rd remote copy is required.
In order to implement cost-effective
disaster countermeasures, the
DataCore software keeps the distant
copy reasonably updated using
asynchronous replication. All you
need is a standard long-distance IP
WAN connection between sites.
Of course, this extra precaution implies
additional investment. Consequently,
it would be reserved for the most
critical information volumes. Having
said that, you may use lower cost
hardware at the DR site to cover these
contingencies. Some of our clients, for
example, replicate to distant branch
offices equipped with only real basic
gear.The storage at opposing ends need
not be the same, because the storage
hypervisor layer takes responsibility for
copying the data between dissimilar
devices in a host-independent fashion.
Undoing Silly Mistakes
While we are on the topic of doom and
gloom, your private cloud strategy must
also be capable of reversing the effects
of virus attacks and silly user mistakes,
regardless of the disk devices used to
store the data. Frequent online disk
backups made possible by snapshots is
one approach to restoration. But as fate
would have it, these untimely incidents
often occur hours after backups;
which means that the consumer
loses a lot of valuable work if they
restore from the prior day’s image.
More recently, the invention of
continuous data protection (Figure 7)
or CDP, allows a more timely rollback,
seconds before the user deleted a file, or
before the virus infection arrived. CDP
acts like a DVR, so you can roll back the
virtual disk image anywhere in time up
to 48 hours.You then surgically retrieve
the file or wipe clean the viral effects.
Some like to call it the “Undo button.”
CDP is usually reserved for select
data volumes because it takes up
more disk space to keep a rolling,
time-stamped log of the data. It
sure is a powerful complement to
online snapshots. Let’s go on now
to a happier subject – expansion.
Expansion
Healthy consumption of your private
cloud will cause it to grow.
Again, you architect for scalability up
front, laying out the groundwork to
increase not only disk capacity, but
throughput.This is accomplished by
scaling out the storage virtualization
nodes commensurate with demand.
DataCore gives you the unique chance
to choose the most appropriate
storage hardware at every expansion
or hardware refresh point. As well as
select the best server platform on which
the storage hypervisor will run.These
too can be upgraded in place to get
more “oomph” from your IT muscles.
Comprehensive layer of
device-independent services
Take a look at this collage (Figure 8)
framing the top level functions included
in the DataCore software.The impressive
capabilities operate across all the popular
storage devices, irrespective of the
assortment of gear that you may have
chosen.The features have been internally
developed from the ground up and are
managed centrally as an integrated
function set from a common console.
Uniform, central management in
combination with automation simplifies
administration of your private cloud
and provides the portability and
expandability necessary to take on
the future. Recognize that one must
step outside the embedded controls
of individual devices to pull off a
successful private cloud deployment.
6
Continuous Data
Protection (CDP)
Rewind to time before
problem occurred
Fig.7-Reversingeffectsofusermistakesandmalware

7. Where to Begin
But where should you start? We would
advise you to consider your entry point
carefully. Gartner, for example, suggests
that the most suitable workloads to
initially transition into the cloud will
be those with short life spans and
more tolerant SLAs.These include
development and test scenarios or sales
demos and on-line training curricula
as well as web servers.These make
excellent candidates, good for fine
tuning the new self-service mechanisms
and usage metering utilities.
Measuring Success
Speaking of measurement, here
are some ideas for gauging success.
It’s important to determine
how you will assess satisfaction
well before you launch.
• Are you more agile?
> Expand to meet spikes
> Wind down when done
• Is your environment more flexible?
• Did you lower costs?
> Higher asset utilization
> Fewer admins
> Cheaper to expand
About DataCore Software
DataCore Software develops the storage virtualization software needed to get the highest availability, fastest performance and
maximum utilization from storage resources in physical and virtual IT environments. It provides the critical 3rd dimension on which the
success of server and desktop virtualization projects hinge, regardless of the models and brands of storage devices used.
© 2012 DataCore Software Corporation. All Rights Reserved. DataCore, the DataCore logo and SANsymphony are trademarks or registered trademarks of
DataCore Software Corporation. All other products, services and company names mentioned herein may be trademarks of their respective owners.
For additional information,
please visit: www.datacore.com
or e-mail: info@datacore.com
0412
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Establish quantitative and qualitative
yardsticks, operational and
financial. And do this from both the
internal IT end as well as from the
consumer’s vantage point.They
tend to be way more objective.
• Are your users happier?
o Responsive apps
o Always available
o Quick recovery from user errors
In closing, we would be remiss not
to mention how important people,
processes and policies determine how
smoothly you will transition into a
private cloud. DataCore’s network of
consultants and trusted advisors can
help you get it right from the outset.
Fig.8-SANsymphony-Vfeaturessupportedacrossdiverse andmutuallyincompatiblestoragedevices
ANALYSIS &
REPORTING
CENTRALIZED
MANAGEMENT
ASYNC
REMOTE
REPLICATION
THIN
PROVISIONING
DISK
POOLING
AUTO-TIERING
HIGH SPEED
CACHING
SYNC MIRRORING
(HIGH-AVAILABILITY)
UNIFIED STORAGE
NAS/SAN
ONLINE
SNAPSHOT
CONTINUOUS
DATA PROTECTION
& RECOVERY
DISK
MIGRATION
LOAD
BALANCING
RAID
STRIPING
CLOUD
GATEWAY