Here I will cover the shrink of ASM diskgroup in Exadata environment running VM’s. The process here is the opposite of what I wrote in the previous post, but have a tricky part that demands attention to avoid errors. The same points that you checked for extending are valid now: number the cells, disks per cell, ASM mirroring, and the VM that you want to change continue to be important, but we have more now. Besides that, the post shows how to verify (and “fix”) if you have something in the ASM internal extent map that can block the shrink.
A quick article about a maintenance task for Oracle Exadata when you are using OVM and you divided your storage cell disks for every VM. Here I will show you how to extend your Grid Disks to add more space in your ASM diskgroup.
The first thing is being aware of your environment, before everything you need to know the points below because, they are important to calculate the new space, and to avoid do something wrong:
- Number of cells in your appliance.
- Number of disks for each cell.
- Mirroring for your ASM.
- The VM that you want to add the space.
The “normal” Exadata storage cell has 12 disks, the Extreme Flash version uses 8 disks per storage. If you have doubt about how many disks you have per storage cell, you can connect in each one and check the number of celldisks you have. And before continuing, be aware of Exadata disk division:
To do this change we execute three major steps: ASM, Exadata Storage, and ASM again.