The answer to that question would depend on the use case, and there are situations when buying flash from someone else will make sense, but I'll pull out a few where I think buying flash from NetApp is the best decision.
1. You already have a FAS array, and are looking to increase performance without needing to increase capacity - in those cases, your best option is usually to buy some SSD's and add them into your aggregate as a flashpool. The advantages of this approach are
- Zero Disruption
- An ability using AWR in ONTAP 8.2.1+ to identify how much flash you are going to need, and how much effect that is going to have
- Cache coherency (ie if you do a snap-restore of your data, the flash layer is aware of the change in the data), this is much harder/impossible to do with host based flash caches
- No Process change for data managment tasks including snapmirror, snapshots, clones, backups, D/R etc
2. You have a new workload that requires consistent (not just average) latency under 2-3 ms, and have operational familiarity with the ONTAP software ecosystem - in that case adding in an All Flash FAS node into your existing cluster, or as a stand-alone option allows you to achieve the results you're looking for, along with the full range of software and data managment features you're already familiar with which reduces training, and increases time to value.
3. You have a new workload that requires reliable consistent sub-millisecond latency with less complex data management requirements- this is where the EF series come into play. They're dense, extremely reliable, store more data than you could expect to fit into any server, provides for hot-swap devices and low impact RAID reconstructions in an extremely reliable and simple to use package.
Thats not an exhaustive list by any stretch of the imagination, The data managment capabilities built into ONTAP that underpin the cloud data fabric are good enough reasons to buy any FAS array, if you're not familiar with them, I strongly reccomend you talk to an SE from NetApp or one of our Partner SE's who can show you how ONTAP's data management can help you transform the way you run your IT.
Any of these three options will come in at a price/performance and price/capacity figure that is more than competetive with the rest of the market, is guaranteed to work, and is backed by our world class support organisation, and by NetApp as a whole. We've got your back, not just for the lifetime of the equipment you buy from us and our partners, but for the lifetime of your data.