Migrating from Windows to Linux with Active Duplicate for standby – problem with

Recently I was working on migrating Oracle database running on Windows, to new hardware infrastructure on Linux. This Oracle version is with us for quite a long time, plus migration from Windows to Linux is quite common (fortunately in that direction…;)), so when I got an error while trying to use Active Duplicate feature to create a standby database, I was quite sure I’ll be able to quickly find the solution either in MOS or elsewhere. Indeed, I found several blog posts with exactly the same error, but solution mentioned there was not working for me.

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Bloom filters and parallel execution

Today I want to share with you another interesting example of solving performance problem which happened in the database used for Business Intelligence purposes. Users were complaining that the performance in kind of staging database (STGDB) was much better than the production one (PRDDB), even though the dataset was exactly the same.

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How to generate subset out of Real Application Testing captures

Originally posted on “Databases at CERN” blog

I’ve already mentioned on this blog very useful Consolidated Database Replay feature, for example while testing unified auditing performance impact (Unified auditing performance) or while investigating problems with hanging workload capture (Starting workload capture hangs – is it really problem with RAT?). But only recently I’ve found that along with this functionality, there was additional and again very handy capability introduced, allowing you to create a subset from already captured workload.

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XFS on RHEL6 for Oracle – solving issue with direct I/O

Originally posted on “Databases at CERN” blog

Recently we were refreshing our recovery system infrastructure, by moving automatic recoveries to new servers, with big bunch of disks directly connected to each of them. Everything went fine until we started to run recoveries – they were much slower than before, even though they were running on more powerful hardware. We started investigation and found some misconfigurations, but after correcting them, performance gain was still too small.

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How to create your own Oracle database merge patch

Originally posted on “Databases at CERN” blog

A little bit scary title, isn’t it? Please keep in mind that definitely it is neither supported nor advised method to solve your problems and you should be really careful while doing it – hopefully not on production environment. But it may sometimes happen that you end up with the situation where creating your own merge patch for Oracle database could not be as crazy idea as it sounds :).

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Oracle 12c – causing problem by solving it!?!

Originally posted on “Databases at CERN” blog

Regular readers of our blog probably already know that for most of our databases we’re using two storage layers to keep our backups – NAS volumes as a primary layer and tapes as secondary one – please check Datafile without backups – how to restore? for more details.

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Nuances of Oracle Managed Files (OMF) and RMAN

Originally posted on “Databases at CERN” blog

Oracle Managed Files (OMF) have many advantages, but the fact that such files could coexist in the same database with manually added (and named) ones, could sometimes lead to confusion. Situation is made worse by the fact, that there is no straightforward way (at least of which I’m aware of…or rather was – please check the comment of Mikhail Velikikh visible on CERN’s blog) to say if the file is Oracle managed or not. Oracle documentation seems to confirm this:

The database identifies an Oracle managed file based on its name.

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