We have four 5240 appliances with 200TB of capacity each one. Each appliance was sold with 128GB at 2016.
Today, we need to upgrade to 8.1.2 / 3.1.2 and Veritas tell us that we should upgrade de memory to 192GB RAM, why? because support have received various performances issues about appliances with MSDP Pools 150TB and above.
My question is, why we need expend our money due a design failure? Why this appliances were not sold with 192GB of RAM? and we must install de RAM upgrade or is only a recommendation? or if we do not we lost the support?
You need to direct these questions to the Veritas representative who told you to purchase additional memory.
IMHO, the additional memory is a recommendation, not requirement.
The 'Veritas NetBackup™ 5240 Appliance Product Description' manual says the following about memory:
System memory configuration (DDR4, RDIMM)
64GB, up to a maximum of 192GBs
Note: When you purchase the first expansion storage
shelf, the Storage Expansion kit that comes with the storage
shelf includes an additional 64 GBs of memory.
After adding the first storage shelf and the memory, you
can increase the appliance memory to 192 GBs by
purchasing an additional 64-GB memory kit.
We have several appliances at or above their recommended ranges and from what we've seen, you will really REALLY want to upgrade your memory to 192 GB if you're running at least v8.1.1.
We're seeing pretty regular memory exhaustion on these 5240 applinaces from everything going on. MSDP has definitely gotten a lot more memory hungry in the last version or two.
YMMV of course depending on your job load but I'd say it's worth the money. Yes it would've been nice if they'd just spec'd them out during purchasing, but the hardware people don't always know what the software programmers are planning on doing a version or two down the road.
You can run TOP command and monitor the memory utilization, then take a call whehter do you need to upgrade or dont need. Performance analyse always take time to resolve and come to conclusion as well.