Clik here to view.
ACFS disk group rebalance
Starting with Oracle Database version 11.2, an ASM disk group can be used for hosting one or more cluster file systems. These are known as Oracle ASM Cluster File Systems or Oracle ACFS. This...
View ArticleClik here to view.
ASM spfile in a disk group
Starting with ASM version 11.2, the ASM spfile can be stored in an ASM disk group. Indeed, during a new ASM installation, the Oracle Universal Installer (OUI) will place the ASM spfile in the disk...
View ArticleClik here to view.
Disk Group Attributes
Disk group attributes were introduced in ASM version 11.1. They are bound to a disk group, rather than the ASM instance. Some attributes can be set only at the time the disk group is created, some only...
View ArticleClik here to view.
How to reconfigure Oracle Restart
The other day I had to reconfigure an Oracle Restart 12c environment, and I couldn't find my blog post on that. It turns out that I never published it here, as my MOS document on this topic was created...
View ArticleClik here to view.
How to resize grid disks in Exadata
This document explains how to resize the grid disks in Exadata (to make them larger), when there is free space in the cell disks. The free space can be anywhere on the cell disks. In other words, the...
View ArticleClik here to view.
REQUIRED_MIRROR_FREE_MB
The REQUIRED_MIRROR_FREE_MB and the USABLE_FILE_MB are two very interesting columns in the V$ASM_DISKGROUP[_STAT] view. Oracle Support gets many questions about the meaning of those columns and how the...
View ArticleClik here to view.
Find block in ASM
In the post Where is my data I have shown how to locate and extract an Oracle datafile block from ASM. To make things easier, I have now created a Perl script find_block.pl that automates the process -...
View ArticleClik here to view.
ASM in Exadata
ASM is a critical component of the Exadata software stack. It is also a bit different - compared to non-Exadata environments. It still manages your disk groups, but builds those with grid disks. It...
View ArticleClik here to view.
Exadata motherboard replacement
This photo story is about a motherboard replacement in an Exadata X2-2 database server (Sun Fire X4170 M2).While setting up a half rack Exadata system, we discovered a problem with the motherboard in...
View ArticleClik here to view.
When will my rebalance complete
This has to be one of the top ASM questions people ask me. But if you expect me to respond with a number of minutes, you will be disappointed. After all, ASM has given you an estimate, and you still...
View ArticleClik here to view.
Where is my data
Sometimes we want to know where exactly is a particular database block - on which ASM disk, in which allocation unit on that disk and in which block of that allocation unit. In this post I will show...
View ArticleClik here to view.
Identification of under-performing disks in Exadata
Starting with Exadata software version 11.2.3.2, an under-performing disk can be detected and removed from an active configuration. This feature applies to both hard disks and flash disks.About storage...
View ArticleClik here to view.
Auto disk management feature in Exadata
The automatic disk management feature is about automating ASM disk operations in an Exadata environment. The automation functionality applies to both planned actions (for example, deactivating...
View ArticleClik here to view.
How many allocation units per file
This post is about the amount of space allocated to ASM based files.The smallest amount of space ASM allocates is an allocation unit (AU). The default AU size is 1 MB, except in Exadata where the...
View ArticleClik here to view.
ASM version 12c is out
Oracle Database version 12c has been released, which means a brand new version of ASM is out! Notable new features are Flex ASM, proactive data validation and better handling of disk management...
View ArticleClik here to view.
Physical metadata replication
Starting with version 12.1, ASM replicates the physically addressed metadata. This means that ASM maintains two copies of the disk header, the Free Space Table and the Allocation Table data. Note that...
View ArticleClik here to view.
Free Space Table
The ASM Free Space Table (FST) provides a summary of which allocation table blocks have free space. It contains an array of bit patterns indexed by allocation table block number. The table is used to...
View ArticleClik here to view.
Allocation Table
Every ASM disk contains at least one Allocation Table (AT) that describes the contents of the disk. The AT has one entry for every allocation unit (AU) on the disk. If an AU is allocated, the...
View ArticleClik here to view.
Partnership and Status Table
The Partnership and Status Table (PST) contains the information about all ASM disks in a disk group – disk number, disk status, partner disk number, heartbeat info and the failgroup info (11g and...
View ArticleClik here to view.
ASM metadata blocks
An ASM instance manages the metadata needed to make ASM files available to Oracle databases and other ASM clients. ASM metadata is stored in disk groups and organised in metadata structures. These...
View ArticleClik here to view.
Tell me about your ASM
When diagnosing ASM issues, it helps to know a bit about the setup - disk group names and types, the state of disks, ASM instance initialisation parameters and if any rebalance operations are in...
View ArticleClik here to view.
The ASM password directory
Password file authentication for Oracle Database or ASM can work for both local and remote connections. In Oracle version 12c, the password files can reside in an ASM disk group. The ASM metadata...
View ArticleClik here to view.
Error count
This tiny Perl script might be used to report the error type and count for ASM disks in engineered systems, including Exadata. In those systems, the ASM uses griddisks, that are created from celldisks....
View ArticleClik here to view.
ASM data scrubbing
According toWikipedia, data scrubbing is “an error correction technique that uses a background task to periodically inspect main memory or storage for errors, and then correct detected errors using...
View ArticleClik here to view.
Quorum disks in Exadata
An Exadata quarter rack has two database servers and three storage cells. In a typical setup, such a system would have three ASM disk groups, say DATA, RECO and DBFS_DG. Usually the disk group DATA...
View Article
![Personal Investments • Re: 401k investments [which to choose?]](http://i.imgur.com/wA51OIw.png)
