7 Must-Know Disaster
Recovery Strategies
Jamie Gruener
Senior Analyst, Enterprise Infrastructure
The Yankee Group
What You Will Learn In This
Session . .
1. The Main Goal: Bullet-proofing Disaster
Recovery Strategies
2. Remote Replication vs. Mirroring Strategies
3. Disaster Recovery and Virtualization: A New
Angle
4. Integrating Mirroring and Replication into
Disaster Recovery Strategies
5. Metro SANs: Options for Remote Mirroring
And Replication
6. Your Network Options: Questions to Guide You
The Goal: Bullet-Proofing
Disaster Recovery Strategies
• You’ve heard the statistics
– ~ $5 billion in computing infrastructure lost in 9-11
tragedy
– Close to 100 businesses declaring disasters in NYC
• You’re here for a reason
– 9-11 was a call to action for all of us
– Disaster Recovery and Business Continuity Strategies
must be done – this is only one leg of a multi-leg
strategy
• You’re entering a new era
– It is now about Business Continuance and Risk
Management
Defining Terms: Remote
Mirroring and Data
Replication
Remote Mirroring generates a mirrored image of
Checklist
•
data on two or more disks
• Data Replication scans data periodically for
changes and copies new data to the other disk or
file system on another system
• Factors to consider
–
–
–
–
Value of data (and lost data) being backed up
Costs for network bandwidth and software
Your existing infrastructure
Product features (OS, File System, Disk or
Application)
Measuring Data Protection:
Point-in-Time to Synchronous
Tip
More
There will be a need for
multiple tools to protect data
Data
Protection
Synchronous
Semi-Synchronous
Lost Transactions Line of Tolerance
Asynchronous
Point In Time
Less
Network Bandwidth Consumed
More
Questions to Consider When
Looking At Remote Mirroring
and Replication
– What are you protecting? (applications,
transactions, files, disks)
– What level of protection do you need?
(We’ll come back to this!)
– What are your network requirements?
– What is your expected budget for this project?
– Is the ROI greater than acquisition costs?
– What will best fit your larger business
continuity strategy?
Best Practice
The Luxury Sedan:
Disk-to-Disk Remote Copy
• Key advantages
– Operates at the disk level
– Can be (not always) less complex to set up and
administer than host-based approaches
– Can offer the benefit of capturing all application
changes. . .
• Key Disadvantages: Costly
– Lacks transaction knowledge or what the data
represents
– Can be wasteful of network bandwidth if not properly
set up
The Rising Alternative:
Block-and-File Replication
• Fundamentals
– Makes comparisons and only copies changes (at disk
or file level)
• Key Advantages
– Can be less expensive
– Can be flexible to replicate all enterprise data
regardless of disk system
– Copies only the most important files/data
– Many-to-one replication architectures available
– Limits amount of data transferred, reducing network
load and cost
• Key Disadvantages
Warning
Block and File Replication
Details You need to Consider
File WAN Replication
Block WAN Replication
• Less expensive, host-based (or array-based) file
and block replication
• Specific to storage vendor, OS or file system
Database Replication
• Typically done by replicating or mirroring log
files
• A number of variations:
– Continuous Mirroring: updates DBMS as
changes(adds, updates, deletes) occur
– Change Data Capture: captures DBMS changes and
stores them until a predetermined replication time
– Full Copy Refresh: replicates entire DBMS copy to
target systems (done to resynchronize DBMS after
outage)
• Trigger-based native DBMS is not usually
appropriate for DR because of high system and
Snapshots: The Hotshots of
Backup
• Establishes a separate identifiable storage entity
and run operations against it
– Primary purpose: backup, testing, conversion and
batch process
• Is dependent on OS, host and array support…
• Advantage: it takes up less network bandwidth
than mirroring
• Disadvantage: resynchronization of data is an art
– If you do not resynchronize, you must build snapshot
mirror totally from scratch
•
New Kid on the Block:
Virtualization and Disaster
Recovery
Virtualization software
offers a new alternative
–
–
–
–
Data replication (over both IP and Fibre Channel)
Snapshot
High Availability Fail-over
A cost-effective approach to disaster recovery
• Key Challenges
– Recreating the virtualization system can be difficult
– Specifying file level information for replication can be
difficult
Warning – Still a relatively new technology, so test well
– Research virtualization players thoroughly
• Ask hard questions about number of customers doing this
Prioritizing Data: Integrating
Mirroring or Replication to Your
Strategy
Tool
Hot Site
More
Remote Disk Mirroring
Data Replication
Importance
Of Data
Snapshot
Campus Disk Mirroring
Electronic Vaulting
Tape Onsite
Less
Tape-Backup Offsite
More
Less
OK, Now What? It’s The
Network, Stupid
• Long-distance Remote Mirroring/Replication
requires significant network integration
– Mission: Connecting two or more islands of storage
– Could be SANs, hot sites, remote disk or tape
• Myriad of network transport choices boil down to
two fundamentals (from the POP out)
– Fibre
– IP
• Where to Start: Evaluate Network Requirements
– Ask storage vendors for requirements
– Map that to service provider bandwidth services
•
Specific Network Challenges
for Remote Mirroring and
Replication
Enterprise network
performance is many times
slower than storage performance
• Things You Could Consider
– What tools do the remote mirroring/replication vendor
provide for performance on a Metro SAN?
• Network throttling – adjusting data amounts sent over wire
• Compression – compressing data to take up less network
bandwidth
• Time-stamping – marking data at time saved or accessed
– Latency isn’t your friend
• Measurable time it takes for an I/O transaction to reach
destination
• Distance is a factor – especially when extending data native limit
• Storage traffic requires high bandwidth, low latency connections
Tip
Metro SAN Puzzle
Pieces
Headquarters
Key Features
Remote Site
Remote
Tape Library
Remote
Disk Storage
Primary
Disk Storage
ATM, T3/E3, OC3+
or Fibre Optic (DWDM)
Service Provider Connectivity Services
Mirroring/Replication Software
Edge of Network Equipment (Director, Router or DWDM)
Metro SAN Network Transport
Options
Key Features
Network
Protocol
Performance
Length of Distance
ESCON
Full performance (200-M
bits/sec. unidirectional)
8 km for full performance,
50% performance @ 20 km
FICON
Bi-directional channel
protocol, runs over at
1.063 G bit/sec.
100 km distance limitation
Dark Fibre
Dedicated Fibre (depends
on transport)
10 km without long-wave
transceivers
iSCSI, iFCP, FCIP
Still in proof-of-concept
Depends on applications,
stage, but promise of 1 TB service, connection points –
per hour over IP
FCIP - primary for Metro
SANs
DWDM - Gigabit
(Optical) Ethernet
Requires high-speed IP
network to connect
Depends on applications,
service, connection points and
IP Network Options
• Private Router Backbones
– Leased, dedicated lines
– Optimized for performance (racing the sun)
• xSP VPNs
– Customer purchases edge routers and ISP provides
shared backbone
– Leverages Multiprotocol Layer Switching (MPLS) for
better Quality of Service
• Internet . . .
– Not a disaster recovery tactic I would trust
Checklist
•
Tips To Consider When
Speaking With Your Service
Provider
Ask your xSP to provide
you what their expertise
is in storage services
– Consider how you could leverage your existing
connectivity services to establish a cost-effective
service contract for your backup services
– Ask for a latency/network performance SLA
– Your primary xSP should have partners to assist with
storage services if they don’t
• Consider leveraging storage vendor relationships
to find service providers that can do integration
• Do or have done a network analysis to determine
requirements for your backup services
•
•
•
•
•
•
•
Metro SAN Challenges:
Things You Need to Ask about
IP
Checklist
Latency and Bandwidth
Security
Complexity
Quality of Service (QoS)
Dropped Packets
Manageability
NOTE: IP storage switch vendors are trying to
solve these things – so gauge them based on this
Does Outsourcing Make
Sense?
Best Practice
• Determine if outsourcing disaster recovery services
for Data Mirroring and Replication services
– Do I have the skills, personnel and infrastructure?
• Outsourcing provides a number of advantages
– Enables enterprise to focus on core competence
– Speeds IT’s ability to maintain and return to business
operations
– Leverages expertise and more plentiful specialized
resources
– Offers mirrored solutions for immediate recovery
– Provides problem resolution expertise that speeds delivery
of services related to backup, security and performance
monitoring
Ask for Help From a
Professional . . .
• This is a complex proposition
• Storage vendors will assist with best backup
technologies
• Service Providers will offer options for services
• Integrators with storage and networking practices
are best candidates for additional implementation
– they are still rare in the world
Evaluate ROI for Disaster
Recovery
• Come up with a ROI calculation for your data
protection strategy
• Guidelines to remember
Best Practice
– Calculated over three-year term
– The higher the ROI, the more favorable the project
– TCO vs. ROI – ROI wins out
• Key factors to be included in ROI analysis
–
–
–
–
Costs: downtime, personnel, assets
Reliability: data replication, mirroring, backups
System performance: how is systems and software utilized
Calculate savings: improved performance, revenue,
processes
Conclusions
• Don’t forget the fundamental goal: Disaster
Recovery
• Consider your options for mirroring/replication
and make a metric to measure them by
– ROI analysis is one way of measuring options
• Be cautious of new technologies
– New IP storage networking technologies and software
offer new options – but you need to be savvy in
deployment
• There’s not one solution – strategize on ways to
prioritize your data protection
Questions?
Jamie Gruener
jgruener@yankeegroup.com