Transcript Achieve Continuous Database Availability with Active

Achieve Continuous Database
Availability with Active-Active
Replication
Sujith Kumar, Chief Technologist
Dell Software
Syamal Bandyopadhyay, Database Solution Architect
Verizon Wireless
Agenda
• Introduction to a five nines system
• Different mechanisms of achieving high availability
• Consider database replication
• Customer Example – Verizon Wireless
• Q&A
2
Software
Introduction
to highly
available
systems
3
Software
Introduction to a highly available system
• What is five nines in terms of high availability?
– Percentage of system uptime in a given year
– *Allowable unscheduled downtime in a given year
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Availability %
Downtime per year*
Downtime per month
Downtime per week
90% ("one nine")
36.5 days
72 hours
16.8 hours
95%
18.25 days
36 hours
8.4 hours
97%
10.96 days
21.6 hours
5.04 hours
98%
7.30 days
14.4 hours
3.36 hours
99% ("two nines")
3.65 days
7.20 hours
1.68 hours
99.5%
99.8%
1.83 days
17.52 hours
3.60 hours
86.23 minutes
50.4 minutes
20.16 minutes
99.9% ("three nines")
8.76 hours
43.8 minutes
10.1 minutes
99.95%
99.99% ("four nines")
99.999% ("five nines")
99.9999% ("six nines")
4.38 hours
52.56 minutes
5.26 minutes
31.5 seconds
21.56 minutes
4.32 minutes
25.9 seconds
2.59 seconds
5.04 minutes
1.01 minutes
6.05 seconds
0.605 seconds
99.99999% ("seven nines")
3.15 seconds
0.259 seconds
0.0605 seconds
Software
Introduction to a highly available system
• Availability and uptime are not synonymous.
– Network outage
• A five nines or higher system is designed to eliminate a single-pointof-failure
– Maintenance activities: hardware, network, operating system, middleware, patches
& upgrades
• Why five nines and not six nines or seven nines?
– Higher Service Level Agreements(SLA) are rare
– Exorbitantly expensive to implement
– Typically does not include scheduled downtime
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Software
Anatomy of a highly available system
Internet & Intranet
Data Center
Load Balancers
Application/Web Servers
Database Servers
Oracle Data Guard
Dell SharePlex
Oracle
RAC
Storage
Replication
Storage SAN/NAS
Disk Mirroring
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Oracle
RAC
Disk Mirroring
Software
Challenges in achieving a highly available system
• Application availability depends on all components in the stack
–
–
–
–
–
Data Centers
Load Balancers, Routers, Switches (Network)
Middle-Tier (Application & Web Servers)
Database Servers (OS Clustering, Database Clusters – Oracle RAC)
Storage (SAN/NAS Block Level Replication)
• Database is the single-point-of-failure by not being able to provide an
always “hot” database for the middle-tier servers to connect to.
– Solution: Maintain a secondary “hot” database for instant fail-over/fail-back
– Provide instantaneous fail-over—Implement database level load-balancing
– Key: Dell SharePlex
7
Software
Consider
Database
Replication
(Dell
SharePlex)
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Software
SharePlex is #1 third party database replication solution
SharePlex is a “High Availability Solution”
for Oracle databases that is affordable,
simple to use & easy to manage.
- Leading database replication software
since 1998
- Gartner 2010 recommends SharePlex to
reduce costs with Oracle Standard
Edition
Worldwide Database
Replication Market Share
2011
Oracle
25.5%
Other
29%
- IDC 2011 SharePlex is #1 third party
solution
IBM
11%
SAP
15%
Quest
Software
19%
Source: Worldwide Database Development and Management Tools 2011 Vendor and Segment Analysis, IDC #237963 November 2012
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Software
What is SharePlex & How does it work?
Target
SharePlex is a logical data replication solution
• Real-time copy of data without impacting
database performance and availability
Source
• Analogous to receiving e-mails seamlessly in
Outlook and mobile devices simultaneously
• Data is replicated from one or more source
database(s) to one more target database at
the same time
• Runs continuously, replicating data from
source to target in real-time with subsecond latency
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Replicate from source to target
with very few limitations
Software
SharePlex Oracle-to-Oracle architecture
On-premises, remote, or in-the-Cloud
Export
Export
queue
Import
Post
queue
SQL
Redo/Archive logs
Post
Read
Post
Capture
Source
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Capture
queue
Cloud target
Target
Software
Why consider SharePlex?
OS/Hardware Clustering
 Requires same type and
version of the operating
system
 In most cases requires
similar hardware
 Requires specialized and
proprietary clustering
software
 Does not provide cross
datacenter redundancy
 Expensive option due to
identical redundant
hardware
 Due to active-passive
configuration, only a single
node within the cluster is
active at all times.
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Oracle RAC
 One physical database,
multiple servers/instances.
− What if the database is
down?
 Allows for workload
distribution, but does not
optimize for different types
of workloads
 All nodes in the same data
center over local/private
network connections.
Extended distance clusters
are limited to 100 KMS or
less
 Does not provide user load
balancing across multiple
databases
 Requires Dataguard for
datacenter redundancy
Storage
Technologies
 Requires proprietary block
level replication software
 High network bandwidth
utilization – replicates
everything
 Most solutions require like
hardware on both ends
 Allows for only one copy of
the data to be hot at any
time
 Redundant copies of the
same data not being used
 Expensive hardware
required for datacenter
redundancy
SharePlex
 Extends to multiple
databases, no outage
 Multiple copies of the
databases - can be
customized for different
workloads
 Allows for true database
load-balancing just like
network load-balancers
 Minimal network
bandwidth utilization
 Minimal load on the
database
 Transparent to hardware,
operating system,
storage & applications
 Provides flexible
datacenter redundancy
Software
Why consider SharePlex?
SharePlex Features
Low overhead on source database (1-3%)
Near real-time replication—target database(s) remains live and accessible
Customizable replication—entire database, selective schemas, tables, columns,
and/or rows
Allows in-flight data transformation if required
Supports mixed environments with differing source/target OS, database editions,
and database versions
 Oracle Enterprise Edition, Oracle Standard Edition, Oracle ASM, Oracle RAC, 9i-12c, Microsoft Windows,
Unix, Linux, Oracle Exadata, operating system clustered environments
Monitoring, automated conflict detection and resolution (predefined and user
defined)
Automated data integrity check and repair (SharePlex Compare and Repair)
Change data capture—change tracking, data integration
All the functionality included in the product—no additional modules needed
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Software
SharePlex:
Peer-to-Peer
Replication
Architecture
SharePlex peer-to-peer replication architecture
Export
queue
SharePlex replication
Post
queue
Capture
queue
Upgrades:
Database
Operating System
Storage
Application
Secondary
production
Capture
queue
SharePlex reverse replication
Primary
production
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Post
queue
Export
queue
Software
SharePlex active-to-active considerations
• Well suited for home-grown application versus off-the shelf applications,
such as, SAP, PeopleSoft etc.
• Business considerations
– Transaction impact – example: inventory management, user profile etc.
– Batch operations (jobs)
• Database considerations
–
–
–
–
Sequences
Triggers
Conflict Resolution
Conflict Validation
• Conflict Avoidance – Geographic isolation, application re-design, adding
date/time columns to database tables
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Software
Case Study
Verizon
Wireless
VZW – Continuous Availability Deployment Architecture
Why Verizon Wireless chose SharePlex ?
Logical Data
Replication with
SharePlex
Oracle Physical Data
Guard
Description
Support Active-Active Configuration
No
Yes
Source/Target having additional database objects
Ok - for some scenarios (generally
not recommended)
Yes
Read/Write Access for all source and target sites
(concurrently both source and target)
Not Supported
Supports
Peer-to-Peer Concurrent Replication (e.g 3 way)
No
Yes
Support one source, multiple target sites
Yes
Yes
Ease of Failover
Yes (using command or Data
Guard Broker)
Yes
Limitations/ Constraints
Unless select appropriate 'mode',
may cause production latency
Latency on target increases with
very high transaction volume
True Disaster Recovery (DR) only
Excellent
Excellent
Failover & Failback
Easy
Always ready to use
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Software
Why Verizon Wireless chose SharePlex ?
Logical Data
Replication with
SharePlex
Oracle Physical
Dataguard
Description
Product Stability
Very Stable
Very Stable
Tuning opportunities
Yes
Yes
Support for Very High Volume
insert/update/delete Transactions requiring
replication
Yes
Yes (Requires tuning)
Handling Foreign Key Constraints
No customization required
Special consideration required
Data Synch time on target site (based on VZW
Observations)
Depends on configuration (max.
availability, max. performance)
Typically less than 2 seconds
Intentional Delay in applying source changes to
targets
Yes, can be configured
Yes, can be configured
Data Resynchronization Between Source and
Target
May require full database refresh
or copy
Can be synchronized using
compare/repair or copy process
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Software
Summary
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Software
Summary
• SharePlex is a high-availability solution for databases
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Ability to maintain multiple active copies of the database
Provides instantaneous database failover and failback
Support for conflict resolution using built-in or custom resolutions
Performance tuning
Flexibility for geographic needs
Supports disparate platforms and versions
Ability to upgrade with no downtime
Software
Questions
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Software
Next Steps
For more information, visit the SharePlex webpage
URL Link: www.software.dell.com/SharePlex
•
Datasheet, Videos, Case studies, White Papers, Technical Briefs, Events/Webcasts
Ask a Dell Software Account Manager for a Proof of Concept (POC)
•
•
•
Download 30-day Trial Software (SC and Support Assistance)
On your own test environment
Dell Cloud Sandbox
Join our SharePlex Community:
URL Link: www.Quest.com/Community-SharePlex
•
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Discussions, Blogs, Expert Advice, Polls, Demo’s, technical documents, etc.
To learn more about
TM
SharePlex
Visit software.dell.com/SharePlex
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