Tag Archives: Goldengate

GaOUG Oracle Tech Day 2016

On March 3, 2016, I’ll be at AMA Executive Conference Centers for GaOUG’s Tech Day 2016. This Oracle user conference promises to be packed with the best content from the best the industry has to offer.  If you will be in the Atlanta area and use Oracle products, consider attending the event!

Specifically, I will be presenting:

Presentation Name:
Application High Availability and Upgrades Using Oracle GoldenGate

Abstract:
This presentation will discuss the techniques and methods used to deploy a High Availability Active / Active configuration using Oracle GoldenGate.  Specifically, discussion will surround how to deploy GoldenGate in a standard configuration, utilization of the built in Conflict Detection and Resolution (CDR) functionality and available methodologies to deploy application or database architecture changes within this configuration.  Focus will also be given to how the DBA resources must also involve other IT resources to achieve a successful deployment.

Click here for more information or to register for GaOUG’s Tech Day.

We appreciate your efforts and look forward to seeing you on March 3. If you have any questions, please feel free to contact me anytime.

Understand Integrated Replicat Performance using the GGSCI STATS Command

With GoldenGate 12c, Integrated Replicat has now become the preferred option to apply transactions (Classic and Coordinated are the others). In order to get the most efficiency out of the Integrated Replicat, it is important to understand what types of operations cannot be applied by the integrated apply server. GoldenGate considers operations which cannot be applied in “integrated” mode to be applied in “direct” mode.

So what is the difference between Integrated and Direct?

“Integrated” applies transactions via a Logical Change Record (LCR) vs. “Direct” which applies transactions with a SQL Statement via OCI. “Direct” also requires that transactions be applied serially vs. “Integrated” where they can be applied in a parallel, coordinated fashion.

There are some limitations to applying changes via a LCR.  The following are items which can only be applied in “direct” mode:

  • DDL operations
  • Sequence operations
  • SQLEXEC parameter within a TABLE or MAP parameter
  • EVENTACTIONS processing
  • UDT Note, if the extract uses USENATIVEOBJSUPPORT to capture the UDT, then Integrated Replicat will apply it with the inbound server, otherwise it will be handled by Replicat directly.

Understanding the types of operations going on inside your database should be one of the first steps in setting up a GoldenGate environment and heavy use of “direct” transactions within an Integrated Replicat will likely reduce the performance of the replicat.

Integrated Replicat Statistics Explained:

  • Total transactions – Total transactions processed by replicat
  • Redirected – Number of transactions for which replicat is redirected to classic mode
  • DDL operations – Number of DDL operations processed in direct mode
  • Stored procedures – Number of Stored procedures in direct mode
  • Datatype functionality – Number of user defined data types processed in direct mode
  • Event actions – Number of event actions processed in direct mode
  • Direct transactions ratio – Percentage of transactions that the Integrated Replicat converts itself to direct mode to apply transactions.

Direct transactions ratio are computed by either:

Direct transactions ratio = (Redirected/Total transactions)*100
(or)
Direct transactions ratio = ((DDL operations + Stored procedures + Datatype functionality + Event actions) / Total transactions)*100

The lower the direct transactions ratio, the better the performance. This is one thing that should be considered when changing to Integrated Replicat.  If the ratio is high, then it could be better to use Classic Replicat to improve performance.

Example of Integrated Replicat Statistics:

 
GGSCI (orcl12c-rac1.localdomain) 4> stats R_TST_R1 totalsonly *.*

Sending STATS request to REPLICAT R_TST_R1 ...

Start of Statistics at 2015-09-14 19:34:26.
 Integrated Replicat Statistics:

Total transactions 11829288.00
 Redirected 0.00
 DDL operations 0.00
 Stored procedures 0.00
 Datatype functionality 295977.00
 Event actions 0.00
 Direct transactions ratio 2.50%
.........


 GGSCI (orcl12c-rac1.localdomain) 2> stats R_TST_R2 totalsonly *.*

Sending STATS request to REPLICAT R_TST_R2 ...

Start of Statistics at 2015-09-14 19:11:48.
 Integrated Replicat Statistics:

Total transactions 2781917.00
 Redirected 0.00
 DDL operations 0.00
 Stored procedures 0.00
 Datatype functionality 733578.00
 Event actions 0.00
 Direct transactions ratio 26.37%
.........

As you can see in the second example, the “Direct transactions ratio” is much higher. Because I know this system, I know that this higher ratio is entirely attributable to the replication of sequence objects. Using this as an example, a few options to lower the Direct transaction ratio and improve performance might include the discontinuation of sequence replication or splitting sequence replication into their own ‘classic’ mode replicat. Of course if current performance is adequate, you could do nothing. I would probably consider changing to classic replicat when the “Direct transactions ratio” approached 50%.

No matter the situation, it is important to understand the statistics which GoldenGate is recording on your behalf. It may lend good insight into what is going on in your environment.

Set Up and Use of ACFS for GoldenGate

Recently, I found myself in a situation where I needed a Linux mount point of sufficient space for GoldenGate binaries / trail files.  I’ve used the Oracle Database File System (DBFS) option in the past, although I never really was a big fan of it since its use creates additional database objects and in my opinion unnecessary additional database I/O as well as additional redo and rman activity.  Based on this, I decided to explore the use of Oracle ASM Clustered File System (ACFS) for this use case.  At first glance, it seemed to be much faster to set up and was available on all nodes by default, which would also allow GoldenGate to fail over to other nodes.  In addition,  ACFS does not require the database to be up so the filesystem can also be used for other purposes.  If you are using this mount solely for GoldenGate, make sure you follow the best practices document which is updated periodically (Oracle GoldenGate Best Practice: NFS Mount options for use with GoldenGate (Doc ID 1232303.1))

***  Refer to the following steps at your own risk and always test for your use case prior to using in a production setting.

Requirements:

  • Root user access
  • Sufficient ASM Space
  • Separate ASM Diskgroup (Optional)
  • Latest Oracle Grid Infrastructure and Database Patchset

Configuration:

Verify that ACFS/ADVM modules are present in memory (on each node):

 $ lsmod | grep oracle

If the modules are not present, the command will return something similar to:
oracleasm              53591  1

If the modules are present, the command will return something similar to:
oracleacfs 3308260 0
oracleadvm 508030 0
oracleoks 506741 2 oracleacfs,oracleadvm
oracleasm 53591 1

If the modules are not present or you would like to ensure that the latest version is loaded, run the following before proceeding (as the root user):

 
$ . oraenv

ORACLE_SID = [CDBRAC1] ? +ASM

The Oracle base remains unchanged with value /u01/app/oracle

# $GRID_HOME/bin/acfsroot install

Reboot the node if the modules were already present and you are reloading them.

Start and enable the ACFS modules on each node:

On each node and as the root user:

# $GRID_HOME/bin/acfsload start
ACFS-9391: Checking for existing ADVM/ACFS installation.
ACFS-9392: Validating ADVM/ACFS installation files for operating system.
ACFS-9393: Verifying ASM Administrator setup.
ACFS-9308: Loading installed ADVM/ACFS drivers.
ACFS-9327: Verifying ADVM/ACFS devices.
ACFS-9156: Detecting control device '/dev/asm/.asm_ctl_spec'.
ACFS-9156: Detecting control device '/dev/ofsctl'.
ACFS-9322: completed

If running Grid Infrastructure, enable the driver modules in clusterware (only on one node as the root user):

# $GRID_HOME/bin/acfsroot enable
ACFS-9376: Adding ADVM/ACFS drivers resource succeeded.
CRS-2672: Attempting to start 'ora.drivers.acfs' on 'orcl-rac1'
CRS-2676: Start of 'ora.drivers.acfs' on 'orcl-rac1' succeeded
ACFS-9380: Starting ADVM/ACFS drivers resource succeeded.
ACFS-9368: Adding ACFS registry resource succeeded.
CRS-2672: Attempting to start 'ora.registry.acfs' on 'orcl-rac2'
CRS-2672: Attempting to start 'ora.registry.acfs' on 'orcl-rac1'
CRS-2676: Start of 'ora.registry.acfs' on 'orcl-rac2' succeeded
CRS-2676: Start of 'ora.registry.acfs' on 'orcl-rac1' succeeded
ACFS-9372: Starting ACFS registry resource succeeded.

Once installation is complete, and the mount is registered with clusterware, these modules will be loaded automatically.

If you like you can double check the driverstate by using the following executable:
usage: acfsdriverstate [-orahome ] [-s]

As oracle user, create an ASM volume for ACFS (run only on one node):

Source in the grid environment.

$ . oraenv
ORACLE_SID = [CDBRAC1] ? +ASM
The Oracle base remains unchanged with value /u01/app/oracle

Create the volume using the volcreate command.
You can use an existing disk group or create a separate one to house ACFS.

$ asmcmd
ASMCMD> volcreate -G DATA -s 10G ACFSVOL1
ASMCMD> volinfo --all
Diskgroup Name: DATA

Volume Name: ACFSVOL1
Volume Device: /dev/asm/acfsvol1-370
State: ENABLED
Size (MB): 1024
Resize Unit (MB): 64
Redundancy: UNPROT
Stripe Columns: 8
Stripe Width (K): 1024
Usage:
Mountpath:

As oracle user, create the filesystem on the volume which was just created:

$ /sbin/mkfs -t acfs /dev/asm/acfsvol1-370

mkfs.acfs: version = 12.1.0.2.0
mkfs.acfs: on-disk version = 39.0
mkfs.acfs: volume = /dev/asm/acfsvol1-370
mkfs.acfs: volume size = 1073741824 ( 1.00 GB )
mkfs.acfs: Format complete.

As root, create an empty directory which will house the file system:

# mkdir -p /acfsmounts/acfsvol1
# chown root:oinstall /acfsmounts
# chmod 770 /acfsmounts
# chown -R oracle:oinstall /acfsmounts/acfsvol1
# chmod 775 /acfsmounts/acfsvol1

As root, setup the file system to be auto mounted by clusterware:

In a RAC 11g environment, you use acfsutil (srvctl may be supported – was not tested and the “-u option” will allow the oracle user to administer the mount):
# . /usr/local/bin/oraenv
ORACLE_SID = [CDBRAC1] ? +ASM
The Oracle base remains unchanged with value /u01/app/oracle
# /sbin/acfsutil registry -a /dev/asm/acfsvol1-370 /acfsmounts/acfsvol1 -t "ACFS General Purpose Mount" -u oracle
In a RAC 12c GI environment, register it with clusterware using the following commands (the “-u option” will allow the oracle user to administer the mount):
# . /usr/local/bin/oraenv
ORACLE_SID = [CDBRAC1] ? +ASM
The Oracle base remains unchanged with value /u01/app/oracle
# srvctl add volume -volume ACFSVOL1 -diskgroup DATA -device /dev/asm/acfsvol1-370
# srvctl add filesystem -device /dev/asm/acfsvol1-370 -path /acfsmounts/acfsvol1 -diskgroup DATA -user oracle -fstype ACFS -description "ACFS General Purpose Mount"

At this point the mount should be ready for read/write and will be automatically mounted by clusterware.

Administration of the ACFS mount:

If you need to resize the mount once created (since you granted control to the oracle user, this command can also be executed by the oracle user:

$ acfsutil size 25G /acfsmounts/acfsvol1
$ srvctl start filesystem -device /dev/asm/acfsvol1-370
$ srvctl stop filesystem -device /dev/asm/acfsvol1-370