Expanding ASM disk group capacity: FlashGrid vs. SAN/AFA

Have you seen this blog “Stop Constantly Adding Disks To Your ASM Disk Groups…” by Kevin Closson? The most interesting part: “The prime concern about adding disks should be the overhead of the rebalance operation.

Even on the all-mighty all-flash XtremIO? Yes! Because it still has only 3GB/s of throughput per brick, which is equivalent to only 30 spinning rust HDDs. Just a single NVMe SSD can give you the same throughput.

But the main idea of Kevin’s blog is that adding new LUNs is more complicated than expanding the LUN capacity, which still seems complicated. What about adding capacity to an ASM disk group the FlashGrid way?

Step 1: Plug in additional SSD(s) in each server
Step 2: flasdhgrid-dg add-disks -G MY_FLASH_DG -d /dev/flashgrid/rac01.mynewssd1 /dev/flashgrid/rac02.mynewssd2

Alternatively, you can start with 2X more capacity than you will ever need in a particular cluster. This is still much less expensive than your favorite all-flash array. The new Intel P3520 NVMe SSDs are only $0.5/GB.