Also, I think you have already learned this, based on the posting, but make sure you are setting up the MSA in a way that you will continue to grow it. In general, it works best, to have similar resources and configuration on each controller and you would grow by staggering upgrade increments between each controller. However, many people do elect to have different RAID types, disk types, or set sizes between the pools and there can be good use cases for this.
So, in your setup: First, with RAID5/6, you want to follow a "power of 2" data disk in your RAID set if possible. With an 8+1, you are already doing that so you are good to go there. The expectation here is that, the next time you need capacity in Pool B, you would add another 8+1 set and continue that on Pool B as necessary. On the A side then the expectation is that you'd grow that out in 10 disk RAID 10 upgrade increments. Mixing set sizes, or RAID types, within a tier of disks in the pool, can produce inconsistent performance. So, if you can keep these upgrade increments going forward, then you should be all set.