Upgrading machines, downgrading memory

Currently we have three Power systems
1 - Power 10 9105-42A, 24 processors, 1280GB memory, SAN NVMe
2 - Power 9 9009-41B, 8 processors, 1024GB memory, Internal SSD's
3 - Power 10 9105-41B, 8 processors, 512GB memory, SAN NVMe

1 - 2 lpars of vios, 1 AIX, 5 lpars of IBM i 7.5, 3 other inactive SGC
lpars for IBM i
2 - 2 lpars of vios, 1 aix, 5 lpars of IBM i, one does only IBM i hosting
IBM i and aix
3 - 2 lpars of vios, 4 lpars of IBM i

1 - Main ERP lpar, Dev lpar, Domino DMZ, Domino internal, SGC toolkit lpar
2 - ERP H/A lpar, dev H/A lpar, Domino DMZ, Domino internal, hosting lpar
3 - Sandbox machine: ERP test, Domino test, domino, archive data

Plan:
Buy SAN for site holding #2. Migrate from internal SSD to SAN.
Move load on 3 to new half wide Power 10 9028.
Move load on 2 to what used to be 3 after shipping it to 2's site.

I do drop #3 during the day, practically on a whim.
Once a quarter we do drop #2 during the day, scheduled in advance.
Never do we drop #2 and #3 at the same time.
#1 has to have downtime on the weekend, after we switch the load to #2.
Done once a quarter.

Why?
1 - Power 9 is getting long in the tooth. Questionable it will run rNext.
Maintenance, etc
2 - Nice excuse to get SAN at that site.
Hey, I've been a huge fan of internal drives and IBM i hosting IBM i. I'm
starting to see the light on SANs though.

What is SGC? Safe Guarded Copy. Basically you can flash copy on a
periodic basis (we do multiple times per day) and if you get infected you
can bring up those other SGC lpars with your choice of copy and do
forensics and recovery.