Author: mac

ASM Configuration Assistant (ASMCA) was introduced in ASM version 11.2. It is used to configure ASM instances, and to create and manage disk groups, volumes and ASM cluster file systems (ACFS). ASMCA can be used in GUI or command-line mode. In this post I will show how to use the ASMCA – in a non-cluster environment…

Starting with version 11.2, ASM runs from the Grid Infrastructure home in both single instance and cluster installs. This is very different to earlier versions so I would encourage you to invest some time in understanding the differences. Here is a quick overview of some of the more interesting features. Integration of Oracle Clusterware (Cluster Ready Services) and ASM Oracle Cluster…

The SYSASM privilege (introduced in 11.1) is fully separated from the SYSDBA privilege in 11.2. If you choose to use this optional feature, and designate different operating system groups as the OSASM and the OSDBA groups, then the SYSASM administrative privilege is available only to members of the OSASM group. [From Oracle® Grid Infrastructure Installation…

The staleness directory (ASM file number 12) contains metadata to map the slots in the staleness registry to particular disks and ASM clients. The staleness registry (ASM file number 254) tracks allocation units that become stale while the disks are offline. This applies to normal and high redundancy disk groups with the attribute COMPATIBLE.RDBMS set…

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 still takes care of disk errors, but also handles predictive disk failures. It doesn’t like external redundancy, but it makes the disk group smart…

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 want to know when exactly is that rebalance going to finish. Instead, I will show…

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 how to work that out.   Database instance   In the first part of this exercise I…

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 cell software processes The Cell Server (CELLSRV) is the main component of Exadata software, which services I/O requests and provides advanced Exadata services, such as predicate processing…

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 griddisks in preparation for storage cell patching) and unplanned events (for example, disk failure). Exadata disks In an Exadata environment we have the following disk types: Physicaldisk is a hard…

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 default AU size is 4 MB. The space for ASM based files is allocated in extents, which consist of one or…