Background
More frequently than we care to imagine, customers require to be able to recover quickly from scenarios where a
database table or data is lost from production either through physical storage corruption or
logical mistakes. Due to the size and
complexity of the environments these issues can take a long time to recover
from. Frequently we find that a customer's recovery time objective
is challenging to meet.
Many customers use storage replication for HA and DR, however this does not protect
against physical storage corruption nor logical mistakes. Any such corruption would be replicated
intact. Corruption issues can be identified by application users but frequently they are identified much later during backups using RMAN block validation.
An Oracle standby database using database flashback still does not solve
the problem because of the time taken to flashback a database and the
administration overhead of managing flashback recovery areas.
Customers require a solution that can start up a clone or virtual copy
database in minutes, from a specific point in time, to quickly source a
database object that can be used to restore the production copy.
Most of the end-to-end recovery time is consumed locating, restoring and
recovering the right version of the database.
It is an iterative process to find the most recent non-corrupted
database copy.
Both Delphix and Oracle Snap Clone could be viewed as alternative
solutions to implement Logical Recovery.
Key Requirements for Logical Recovery
There are three key requirements to implement
a logical recovery solution.
1. Synchronising with Source Database(s)
This solution requires
that you have access to a continuous rolling window of backups since you will
need to restore database objects (usually tables) from a version of the production
database immediately prior to the corruption or fault occurring. You want to restore the latest good copy of
the database object(s).
2. Provisioning Database Copies
The solution must also be
able to provision a database copy to a point-in-time extremely quickly as this
may have to be performed several times before the most up-to-date ‘good’
version of the object is located.
3. Simplicity
The entire recovery
process must be automated, easy to use and fast. Recovery scenarios are stressful events and
intuitive ease of use avoids artificial delays during the recovery process
itself.
Oracle EM 12c DBaaS Snap Clone for Logical Recovery
1. Synchronising with Source Database(s)
For continuous synchronisation with a source
database Oracle requires a replication method to maintain an up-to-date Test
Master from which all clones will be provisioned.
The replication method is typically an Oracle Data
Guard physical standby.
The storage on which the standby is running is
limited to Sun Storage, NetApp or EMC.
You can use any other storage as long as you have a server running
Solaris to create and manage a ZFS file system on that storage.
Challenges
1.
Requires a licensed database server to run the standby database instance
2.
Enough storage for a full physical copy of the source databases
3.
Administration overhead managing the standby database, for example,
synchronising nologging operations on the source database and physical changes
including datafile addition and deletion
4.
Limited set of storage options
5.
Additional licenses are required if using 3rd party, NetApp
or EMC, snapshots capabilities
2. Provisioning Database Copies
Oracle Snap Clone can
provision point-in-time clones of the Test Master from storage snapshots.
Challenges
1.
All target servers where clones are deployed must be licensed with
·
Oracle Database Lifecycle Management Pack
·
Cloud Management Pack
3. Simplicity
Even
customers who are familiar with Enterprise Manager may find that installing,
configuring and managing DBaaS Snap Clone is non-trivial.
Delphix for Logical Recovery
1. Synchronising with Source Database(s)
Delphix synchronises with
source database seamlessly using an RMAN initial full backup and incremental
forever backups including transaction log files. All the ingested data is compressed to
typically 50% of the size. The
compression saves storage for the source and virtual copies but more
importantly improves the IO performance of virtual copies.
When we perform an
incremental synchronisation (SnapSync) we can also validate the integrity of
the database using validated synchronisation.
This will ensure that the backup copy we have can be used for recovery
and the data is intact. It also speeds
up the process of provisioning a virtual copy.
The validated SnapSync could be run as frequently as required to support
the recovery time objective.
Advantages
- With Delphix there is no requirement for a Standby Database
- Synchronisation is automatic regardless of any database changes (nologging, physical etc)
- Easy to define a retention policy for the span of time you want to keep backups
- Validated Sync can continuously check for corruptions and recoverability of the Delphix database copy
- No additional Oracle licenses required
2. Provisioning Database Copies
Delphix can provision a
virtual copy of a database in minutes to any point-in-time within the retention
period of the source copy. Provisioning
can be performed via the GUI, CLI or API.
You can also provision as many copies as you want concurrently, from
independent points in time to accelerate the time to restore service.
3. Simplicity
Delphix is easy to install,
has automated discovery of source systems, once synchronisation is established
with a retention period and one or more target servers are configured to
provision virtual databases to there is very little monitoring or maintenance
required.
Key advantages of Delphix over Oracle DBaaS Snap Clone
1.
Easy to install and configure
2.
Complete automation of restore and recover process
3.
No requirement for multiple standby environments, avoiding setup,
maintenance, monitoring, server capacity and licenses.
4.
Continuous validation and recovery of ingested backups as a further
safeguard against corruptions and providing early detection of issues.
5.
Reduced Storage requirement
6.
Lower maintenance
7.
Minimal Licensing, with no additional licenses required if want to
expand usage for provisioning non-production database copies
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