Ronny Egners Blog

This is a short article about ACFS and the acfs snapshots feature – a new 11g Release 2 feature: How to create, work with and drop a snapshot.

ACFS is the ASM Cluster File System and ships with Oracle 11g Release 2. For using ACFS first of all an ADVM volume must be created and an ACFS file system created on top of it. The same ACFS file system is available on all nodes in the cluster. The data itself is stored in an ASM disk group. More information can be found here. The documentation is available here and here.

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The following matrix shows a matrix of operating systems, database version and certification status. All information is taken from the database documentation and information freely available on the internet (e.g. oracle forums, blogs). The information is structured first into operating systems (Windows, Linux, Other) and further divided into version numbers and architecture (32-bit or 64-bit).

Table annotations

• n/a: “not supported or certified”; for this there might be several reasons, for instance:
  • operating system too old
  • mixing 32-bit operating system with 64-bit database or vice versa
  • database for this platform not available
• Projected: will be certified in the future; at this point of time this also counts as “not supported”

Windows

Linux

Solaris, HP-UX, AIX

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Data Pump is a great improvement of the old fashioned export and import utility. Data Pump is available since 10g Release 2 and offers some nice new features, for instance a API to be used to start exports and imports from within the database. Beside these features there is one major feature using data pump: SPEED. Data pump is by factors faster that traditional export/import.

A more comprehensive description about data pump can be found here or here. Documentation for version 11g Release 2 is available here.

One of the downsides of data pump – especially for unix dbas – is that data pump in oracle 10g is unable to compress the data (however it does compress metadata but savings are negligible) and is also unable to use pipes (which can be used to compress data if the software does not support this).Starting with 11g Release 1 the ability to compress data was added but required the expensive “Advanced Compression” license.

Another useful new data pump feature is the so called “network mode” which transfers the data to be imported over a database link instead of exporting the data into a file, transferring the file(s) to the destination server and importing the the export file(s).

This article is a short documentation about how to use data pumps network mode feature for importing data to remote (source and destination database are different) or local (source and destination database are the same) database instances. For general information how to use data pump or an introduction refer to the oracle documentation.

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The following post is a short description how to copy schema statistics from one schema to another. Basically there are two methods for doing this:

• using DBMS_STATS or
• using Data Pump

This is especially useful when doing large data transfers between either schemas or databases and statistics are needed fast. Remember that data density, row chaining or index cluster factor changed due to the data import and index rebuilds.

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In this post we will reproduce a more common scenario: We will forcefully remove the asm disk device from the operating system. This simulates common errors like a crashed storage system or some kind of interrupted connectivity (cable plugged, power failed, …).

All test are available here.

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When backing up servers with any kind of backup software you will most certainly backup your data.

But how about the system configuration?

When restoring a system from scratch do you know how big the disks were, what partition sizes, what disks used (in case you have more than one disk), if you used an LVM and so on.

Think about it!

In this article i wanted to summarize what system information should be collected to enable a fast and error free restore.

Update: There is an article regarding this topic here.

Feel free to add your own comments and suggestions.

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