Oracle Partitioning and Standard Edition

Oracle Partitioning is a great feature.

Large tables can be partitioned into smaller pieces based on data ranges, values or dates, and queries that are designed to respect the partitioning scheme can automatically discount from consideration partitions that do not contain applicable data.

Partitions can be added or removed, moved, made read only, and so on.

That is only a very brief overview of the benefits of partitioning to large database tables, and anyone who had designed a data warehouse will understand why this feature is so powerful.

But it is also very expensive.

Oracle Partitioning is only available as an add-on cost to the already expensive Enterprise Edition license.

But what about if you want to realize some of these benefits without paying for the Partitioning option?  Taking this even further could we implement some form of Partitioning with the massively less expensive Standard Edition?

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A method to fix a corrupted SPFILE in ASM

So you’ve made some changes to your SPFILE, and since the parameters you want change cannot be made to a running instance, you used the scope=spfile clause.

Now you go to restart your database, and you find the instance won’t start!

[oracle@sio01-mgmt sql]$ srvctl start database -d dbbench
PRCR-1079 : Failed to start resource ora.dbbench.db
CRS-5017: The resource action "ora.dbbench.db start" encountered the following error:
ORA-01078: failure in processing system parameters
. For details refer to "(:CLSN00107:)" in "/u01/app/oracle/diag/crs/sio02-mgmt/crs/trace/crsd_oraagent_oracle.trc".

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Resolving ORA-27090: Unable to reserve kernel resources for asynchronous disk I/O in Oracle 12c

I have been running into some problems recently with 12cR2 databases and Kevin Clossons’ SLOB tool.

The SLOB setup.sh script allows for the concurrent loading of multiple schemas, and if you are loading a large amount of data, being able to load concurrently is a significant time saver.

With LOAD_PARALLEL_DEGREE set to 8, I got the following error:

ORA-27090: Unable to reserve kernel resources for asynchronous disk I/O
Linux-x86_64 Error: 11: Resource temporarily unavailable
Additional information: 3
Additional information: 128
Additional information: 140728056780720

These servers were new Dell R630s with plenty of horsepower, so the idea that just 8 parallel threads would cause this type of a failure was puzzling.

Further investigation of the trace file showed that the problem occured on the index shrink command:

SQL> SQL> ALTER INDEX i_cf1 SHRINK SPACE COMPACT
*
ERROR at line 1:
ORA-12801: error signaled in parallel query server P13L, instance
sio04-mgmt.asp.lab.mcl:slob4 (4)

After some time investigating, it seems Oracle 12c has a much higher target for PARALLEL_MAX_SERVERS and PARALLEL_SERVERS_TARGET.  In my case, PARALLEL_MAX_SERVERS had defaulted to 2240.

Since the SLOB data load uses the parallel query option, Oracle was spawning thousands of slave processes all trying to issue ASYNC IO.

So I set the numbers to what I considered more reasonable:

SQL> alter system set parallel_max_servers=400 sid='*';

System altered.

SQL> alter system set parallel_min_servers=40 sid='*';

System altered.

SQL> alter system set parallel_servers_target=400 sid='*';

System altered.

Now SLOB was able to load data with eight concurrent processes.

Restore an RMAN backup to a different host

 

Oracle RMAN is a powerful tool with many features for recovering datafiles, tablespaces or even single blocks, as well as cloning databases for non production uses.  However restoring a database to an entirely different server (or set of servers) it was backed up from is a somewhat cumbersome process.

In this post we will restore an RMAN backup to a new host, keeping the same database name and datafile names.

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RMAN Restore fails with “PSDRPC returns significant error 3113”

When using RMAN to restore a database to a new host, the recover database step fails with:

Crosschecked 43 objects
PSDRPC returns significant error 3113.
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of recover command at 03/18/2017 19:31:23
ORA-03113: end-of-file on communication channel

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EMC Unity Storage Performance testing with Oracle ASM and SLOB

I’ve been testing the new EMC Unity 600F all-flash storage array with an Oracle database to determine the impact of storage compression on Oracle I/O performance.  To do this I have been using Kevin Closson’s SLOB tool.

SLOB is an excellent tool for testing I/O performance as seen by Oracle.  Unlike Swingbench which mimics a real application and therefore spends much of its execution cycle on the server CPU, SLOB concentrates exclusively on generating I/O from the Oracle stack.

Conversely, don’t expect SLOB to generate meaningful data to test ranking or sorting operations inside of Oracle.  SLOB generates entirely synthetic data that is meaningless from an application standpoint.

The following posts covers using SLOB to test I/O performance, and what was learned from the testing against the Unity 600F all-flash array.

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