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Oracle recommends that an ASM diskgroup is shared between multiple databases to keep the number of diskgroups down to a manageable level. In the case where multiple databases share common I/O characteristics, are of similar version and hardware levels and of largely equal importance to an organization then consolidation of ASM diskgroups across multiple databases may be beneficial, but that approach will limit the effectiveness of individual crash-consistent database snapshots.
However where one system, such as an ERP, is clearly of higher importance than other databases, uses a significantly different release of Oracle or is likely to require a significantly more complex upgrade strategy than other systems, then such consolidation may introduce logistical headaches or performance issues later on.
Finally, if ASM diskgroups are shared among multiple databases any upgrade of the ASM infrastructure will require a lockstep upgrade of all databases.
Mixing of production and non-production data in the same ASM diskgroups is not advised.
When designing the ASM diskgroup layout, the DBA should be aware of Oracle’s ASM limits, as shown in Table 2.
Table 2. ASM limits
Maximum |
ASM 11g |
ASM 12c |
Diskgroups per ASM instance |
63 |
511 |
ASM disks per ASM diskgroup |
10,000 |
10,000 |
ASM disk size |
2 TB |
32 PB |
Storage size |
20 PB |
320 Exabytes |
Files per ASM diskgroup |
1 million |
1 million |