Delphix for DBAs by Jonathan Lewis

Saving time and reducing risk
with Delphix
Jonathan Lewis
jonathanlewis.wordpress.com
www.jlcomp.demon.co.uk

Delphix for
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Who am I ?
Independent Consultant
31+ years in IT
26+ using Oracle
Strategy, Design, Review,
Briefings, Educational,
Trouble-shooting
Oracle author of the year 2006
Select Editor’s choice 2007
UKOUG Inspiring Presenter 2011
ODTUG 2012 Best Presenter (d/b)
UKOUG Inspiring Presenter 2012
UKOUG Lifetime Award (IPA) 2013
Member of the Oak Table Network
Oracle ACE Director
O1 visa for USA
Jonathan Lewis
© 2013 - 2014

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Topics
• Testing requirements
• Virtual Databases
• Basic DxFS
• Oracle Backups
• Possible uses
Jonathan Lewis
© 2013 - 2014

Testing is difficult (a)
Last night this report took 45 minutes instead of 3.
Why ? Make sure it doesn't do it again tonight.
It seems to be running as expected right now
Maybe it was resource contention - any clues in AWR.
Maybe it was a change in plan - how to prove it.
What's the fastest way to eliminate possibilities ?
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It's not instrumented properly.
It didn't get captured in any AWR snapshots.
There are fragments in historic ASH
Jonathan Lewis
© 2013 - 2014

Testing is difficult (b)
I believe I can make this part of the batch run six
times faster - when can I test it ?
You can have pre-prod at 3:00 am the day after tomorrow.
But it's going to take 2 hours to prime the data correctly
(provided nothing goes wrong while we're priming it)
Give me 5 minutes and you can have a copy of prod as
it was last night at the correct point in the batch
… and the same for the previous night
… and the night before
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Jonathan Lewis
© 2013 - 2014

Testing is difficult (c)
The best place to test is on production
Right data, right stats, right hardware, right activity
End-users may disagree.
If nothing else competition for resources is a threat
Next best is a "good" copy of production
Still unlikely to emulate performance characteristics
Usually adequate for "sanity" checks
How "good", how often, how quickly, how private ?
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Jonathan Lewis
© 2013 - 2014
The best way to avoid big mistakes in development is to test on a carefully
timed full-scale copy of the production data.

Testing is difficult (d)
Warning:
Even if you had a disk-based clone of production on
exactly the same hardware across the entire stack
you still have to worry about the impact of:
The target is to maximise your level of confidence
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Basic concurrency effects
Oracle-related resource contention
Read-consistency
Historic caching effects
Other people's tests
Jonathan Lewis
© 2013 - 2014
No matter how good your test system there are always imponderables that
require some careful thought when you try to interpret test results.

Could be a "logical snapshot" of production
Probably better to use a copy
Plus N modifying instances
"local" copies of blocks the instance has modified
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Virtual DB
Avoids duplicating data storage
One full, read-only copy
Jonathan Lewis
© 2013 - 2014
If you have only one development project a very recent backup may be
adequate, but if you have many projects it's best to keep them separate.

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Options (a)
Storage
device
Jonathan Lewis
© 2013 - 2014
Production
Server Development
Production DB
Server
"Logical copy" Dev Delta
It is possible to have a solution that takes a "logical copy" of the production
system on the same SAN, and then writes modified blocks to a separate area

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Options (b)
Production DB
You could use "split mirror" technology to make a fast, cheap, local copy of
Production and associate multiple deltas with it.
Jonathan Lewis
© 2013 - 2014
Split Mirror Dev1 Delta Dev2 Delta

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Options (c)
Production DB
You could take a copy of production to another storage device, and then use
the "delta" technology there. This helps to protect your production system.
Jonathan Lewis
© 2013 - 2014
Backup Copy Dev1 Delta Dev2 Delta

Considerations
Minimum impact on production system
Ease of creating/discarding a virtual database
Speed of refreshing "primary" copy
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Delphix uses rman backups with log transport
Very simple once target machine is setup
The ideal would be a "rolling-history" mechanism
Jonathan Lewis
© 2013 - 2014

Windows 7, VMWare Server 2.0 - 16GB RAM, 4 CPU, 2 x 500GB drives
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My Sandbox
OEL 5.6
Oracle 11.2.0.4
Production:
s/w and database
with "delphix" a/c
Jonathan Lewis
© 2013 - 2014
Delphix 3.0
Backups and virtual databases
OEL 5.6
Oracle 11.2.0.4
Development:
s/w and config files
with "delphix" a/c

Basic architecture
Independent system - running DxFS.
Acts as a network file server for vDBs
Registers source and destination machines
Takes rman backups from source machines
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Uses transparent compression to save space
Keeps rolling backups using minimum space
Mounts backups on destination machines
Uses DxFS technology to present virtual DBs
Best effect - when a small fraction of the database changes
Jonathan Lewis
© 2013 - 2014

t0
Metadata
(associates logical block
with physical location)
a b c d e f g h i
Data (i.e. filesystem blocks)
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DxFS
Jonathan Lewis
© 2013 - 2014
128 entries per block
Variable number of sectors per block
Set the DxFS block size to match the database block size. DxFS blocks are
transparently compressed to the smallest number of sectors possible.

"Updates"
t0 t1
a b c d e f g h i
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Jonathan Lewis
© 2013 - 2014
b' c'
Data only becomes visible
when root block is written
You don't overwrite blocks on disc with a new version, you write a new copy
and maintain the index (and you don't overwrite index blocks either).

Multi-version
t1
a d e f g h i
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Jonathan Lewis
© 2013 - 2014
b' c'
This is the latest state of our file system - but we don't have to release the old
versions of the blocks we "changed".

t1 t0
a d e f g h i
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Aging data
Blocks that can be freed
when we don’t want the
older snapshot any more
Jonathan Lewis
© 2013 - 2014
b c
b' c'
Over time we may "overwrite" many of the most recent blocks, and be able to
free old copies of those blocks, keeping a lot of the oldest original blocks

Working with Oracle
• Start with an rman backup
• Take regular incremental backups
– Delphix has custom code to apply them efficiently
• For a vDB pick a recovery point
– Delphix code mounts the file system, configures the
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target, and sets up the instance.
Jonathan Lewis
© 2013 - 2014
Time for a demonstration: (identify source and target machines, identify
source d/b, create first backup, create vDB).

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Traditional Backups
Level 0
Level 1
Jonathan Lewis
© 2013 - 2014
Data Redo
Level 1
Data Redo
Level 1
Data Redo
Redo

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Delphix calls rman
CONNECT TARGET /
SET ECHO ON;
SET ENCRYPTION OFF;
RUN {
SET NOCFAU;
ALLOCATE CHANNEL DLPX_CHANNEL_0 DEVICE TYPE sbt … ;
ALLOCATE CHANNEL DLPX_CHANNEL_1 DEVICE TYPE sbt
PARMS='
Jonathan Lewis
© 2013 - 2014
SBT_LIBRARY=/home/oracle/toolkit/Delphix_.../libobk.so,
ENV=(
DELPHIX_CONFIG_DIR=/home/oracle/toolkit/Delphix_.../lib64,
DELPHIX_URL=http://192.168.91.167:8341/context/servlet,
DELPHIX_HID=SNL.1.17.F76CB2C54939EE8FF470FA
)
'
;
SET COMMAND ID TO 'SNL.1.17.F76CB2C54939EE8FF470FA';
BACKUP NOEXCLUDE FORCE COPIES 1 AS BACKUPSET
FILESPERSET 5 TAG 'DLPX201306181730521301FE51F5B5' ARCHIVELOG
FROM SCN 6726134
;
}
exit

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Delphix Backups
Level 0
Level 1
Jonathan Lewis
© 2013 - 2014
Data Redo
Level 1
Data Redo
Level 1
Data Redo
Redo
Delphix unpacks the rman backups as they are generated and applies them
(excluding redo) to the level 0 backup.

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Delphix Backups
Jonathan Lewis
© 2013 - 2014
DxFS doesn't overwrite changed blocks, though, it writes them to a separate
location and creates some new index entries.

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Delphix Backups
Jonathan Lewis
© 2013 - 2014

Redo
Rolling forward creates some new (f/s) blocks and pointers, and a new root block.
Every new vDB gets its own "index root block".
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Pick your version
Pick an index to create your vDB
Jonathan Lewis
© 2013 - 2014
Redo Redo Redo
Delphix rolls forward (and back) from the associated redo

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Rolling history
Jonathan Lewis
© 2013 - 2014
Redo
To delete history Delphix can do an optimised walk of "old" indexes and
delete any blocks for which a newer block has been created.

– Take copies of archived redo log
– vDBs roll forward and open at any desired SCN
– Frequent snapsync operations reduce time to roll forward
– Can do "pre-provisioning" (continuous rollforward)
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Options
• Snapsync
– Take regular rman backups "from SCN"
– vDBs open at granularity of snapshots
• Logsync
Jonathan Lewis
© 2013 - 2014

Last night this report took 45 minutes instead of 3.
Why ? Make sure it doesn't do it again tonight.
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Solutions (a)
Create a vDB as at report start time last night.
It's got yesterday's data and yesterday's stats
Run the report.
Does it take 2 hours or 3 minutes ?
Jonathan Lewis
© 2013 - 2014

Solutions (b)
I believe I can make this part of the batch run six
times faster - when can I test it ?
Create a vDB as at the right moment from last night.
Run the old code
Create a vDB as at the right moment from last night.
Run the new code
Check results match, check workload
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Rinse and repeat for every night last week / month.
Jonathan Lewis
© 2013 - 2014

– Create a vDB to gauge the side effects of index changes
– Some idea of time to build.
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Ideas (a)
• Stats Tests
– Create a vDB to generate / fake different statistics
• E.g. histograms, global partition code strategies
– Run test-suite
– Transfer stats to production if appropriate
• Index tests:
Jonathan Lewis
© 2013 - 2014

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Ideas (b)
• Upgrades / Patches:
– Create a vDB from production
– Create a new Oracle Home for new s/w version
– Run upgrade
• Single instance conversion to RAC
– you install the clusterware etc.
– Delphix will give you the database and instances
Jonathan Lewis
© 2013 - 2014

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Ideas (c)
• Hand-off to QA
– Create a vDB
– Apply and test development changes
– Create vDB from development vDB for QA to test
– Continue development
• Rinse and repeat
• Drop "spare" QA vDBs
Jonathan Lewis
© 2013 - 2014

– But time for obfuscation needed only once per "generation"
– (obfuscate once, use many)
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Ideas (d)
• Obfuscation:
– Create a vDB from production
– Run obfusaction code.
– Create vDB(s) from obfuscated vDB.
• Probably more restrictive
Jonathan Lewis
© 2013 - 2014

Performance
• Under any circumstances, changes in
discs, CPU, memory, and users make it
difficult to compare performance.
– Check statistics - SQL by reads, segments by reads
• Sharing (cached) blocks on the Delphix
may make some I/O faster.
• CoW may make tablescans / IFFS slower
• Effects on writes may vary with scatter
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Jonathan Lewis
© 2013 - 2014

Conclusion
• Questions to ask about virtual databases
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– How much extra workload (at source)
– How much space needed (and where)
– Simplicity of generation
– Simplicity / overhead of refresh
• Versatility
– One big backup is good for everything !
• Interpretation of performance
Jonathan Lewis
© 2013 - 2014

Delphix for DBAs by Jonathan Lewis

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