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All posts by William Sescu

William Sescu
Consultant

William Sescu has more than 17 years of IT experience, more than ten years in Oracle and Unix Consulting. He is specialized in Oracle Database High Availability, RAC Clusters, DataGuard, Backup/Recovery and Database Migrations. Besides that, he is also specialized in different Unix flavours, especially in Linux and Solaris, and also in virtualization technologies like VMware and Solaris Containers. In the OpenSource world, William Sescu is specialized in the areas of MySQL/MariaDB and Galera Clusters. William Sescu also is a Trainer for different disciplines like “Linux for Oracle DBS’s”, “Oracle RMAN”, “Oracle Flashback Techniques” and many more. Prior to joining dbi services, William Sescu was working as an Oracle Database Administrator for Amadeus Data Processing in Germany. William Sescu has two Oracle Master Degrees, one in Oracle 12c and one in Oracle 11g, and several Oracle Certified Expert certifications. Besides that, William Sescu is OCM MAA 12c. A certification, that only a few people worldwide have.
William Sescu

Oracle 12c – Why you shouldn’t do a crosscheck archivelog all in your regular RMAN backup scripts

By | Database Administration & Monitoring | 3 Comments

Crosschecking in RMAN is quite cool stuff. With the RMAN crosscheck you can update an outdated RMAN repository about backups or archivelogs whose repository records do not match their physical status. For example, if a user removes archived logs from disk with an operating system command, the repository (RMAN controlfile or RMAN catalog) still indicates that the logs are on disk, when in fact they are not. It is important to know, that the RMAN…

 
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William Sescu

OUD – Oracle Unified Directory 11.1.2.3, Oracle generates more and more LDAP lookups with every release

By | Database Administration & Monitoring | No Comments

After installing OUD some time ago, I was doing some tests to see how it performs, and as long as I do ldap searching on the command line it looks very good. I am running Unified Directory 11.1.2.3.170117 (latest PSU), just for the protocol and I use the OUD only for TNS resolving and nothing else. However, Oracle clients are not connecting with “ldapsearch”, they are using “sqlplus” and the TNS name is resolved automatically…

 
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William Sescu

OUD – Oracle Unified Directory 11.1.2.3 Tuning, It is not always the servers fault

By | Database Administration & Monitoring | No Comments

The default configuration which is shipped with OUD is not meant to be ready for enterprise usage. The default settings of OUD are targeted at evaluators and developers who run equipment with limited resources, and so it is quite likely that you run into performance issues if you don’t change anything, before going into production. The OUD performance depends on a lot of things like Network configuration/routing/firewalls/bonding OUD version and configuration (Replication, TLS) Java version…

 
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William Sescu

OUD – Oracle Unified Directory 11.1.2.3 Backups Tips and Tricks

By | Database Administration & Monitoring | No Comments

Backing up an OUD consists of several components The OUD software itself The OUD back end data The OUD configuration The OUD logical export as a ldif file However, in this post I would like to take a closer look at the back end data. Unlike the old OID, the OUD directory server uses the Berkeley DB Java Edition (JE) as its primary back end. The OUD backup command allows you to backup all back…

 
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William Sescu

10th CH Exadata Community Meeting

By | Database Administration & Monitoring | One Comment

Yesterday (15th of March), the 10th Switzerland Exadata Community Meeting took place. It was not a meeting only about Exadata, but also about the Oracle Database Appliances which became more and more popular. It is interesting, how many companies in Switzerland already use Exadata’s or ODA’s. A big topic was the Exadata 12.2.1.1.0 software release which includes over 30 unique software features and enhancements, like better analytics, better transaction processing, better consolidation, more secure and…

 
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William Sescu

Oracle 12c – Is VKTM always your top process?

By | Database management | 2 Comments

If VKTM is always your top cpu consuming process, then this blog might be something for you. Especially in virtual environments, I have seen often the VKTM process as the top process, even if the VM was idle. So, I am burning CPU without any obvious benefit. So what is the reason for the high CPU consumption? Well … it can a combination of many things like not correctly working NTP, missing VMware Tools, but…

 
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William Sescu

Oracle 12c – How to Recover lost DataGuard Broker Configuration Files

By | Database Administration & Monitoring, Database management | No Comments

If you are using RMAN to back up your database, you are already doing the right thing. However, RMAN does not take care of everything. e.g. it is not backing up the following things, to mention just a few. Oracle Home Grid Infrastructure Home Data Guard broker files Password File SQL*Net file like ldap.ora, sqlnet.ora, tnsnames.ora and listener.ora /etc/oratab OS audit files Wallets /etc/sysctl.conf and limits.conf OLR and OCR Voting Disks ASM Metadata passwd, shadow,…

 
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William Sescu

Oracle 12c – Recreating a Controlfile in a Data Guard environment with noresetlogs

By | Database Administration & Monitoring, Database management | No Comments

Sometimes you might run into situations where the controlfile does not represent the backups and archivelogs correctly, because of a mismatch of the control_file_record_keep_time and the RMAN retention. The controlfile has non circular and a circular records. Non circular are e.g. database information, redo threads, datafiles and so on. These non circular records don’t age out, however, they can be reused, e.g. when a tablespace is dropped. The circular records are e.g. the log history,…

 
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William Sescu

Oracle 12c – How to correct the error: “RMAN-20005: target database name is ambiguous”

By | Database Administration & Monitoring, Database management | No Comments

I do have a Data Guard environment, where I have configured the RMAN DB_UNIQUE_NAME persistent setting for my primary and the standby. With the RMAN DB_UNIQUE_NAME settings I am able to run reports my Oracle Data Guard environment from any database. I could e.g. list all archivelogs for SITE1 from SITE2 or the other ways around. Or I could show all persistent settings for SITE1 from SITE2 and of course the other way around. The…

 
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William Sescu

Oracle 12c – Combining Flashback Drop and Flashback Query

By | Database Administration & Monitoring, Database management | No Comments

If you think that Flashback Drop feature just brings back your table, then this is only half of the story. It does much more than that. Besides undropping the table, it also brings back your constraints, your indexes, your trigger, your grants and the statistics as well. The ugly part is, that the flashback drop brings back some strange object names e.g. your indexes and constraints with names like “BIN$…” or alike. Maybe something you…

 
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