It’s been a while since I posted about my unhappiness with NetApp’s FAS2020. And while we’ve replaced our 2020 with a 2050, I still get a lot of traffic to those pages, and a few emailed questions from prospective or new 2020 owners asking about the so-called 8TB limit. Here’s a summary of what I know:

• The aggregate limit appears to actually be 7TB, not 8TB as is commonly stated. I’m not sure what the source of this confusion is, but error messages on the 2020 and NetApp’s docs on NOW seem to bear this out.
• If you have 1TB drives, your maximum aggregate size is 4.36TB from a single DP RAID group of 8 drives. This is before aggregate and volume snap reserves, which you can adjust to fit your needs, but are configured by default to be five and twenty percent, respectively.
• If you have 750GB drives, your maximum aggregate size is 4.91TB, from a single DP RAID group of 11 drives – again, before aggregate and volume snap reserves.
• If you have other drives that you’ll be using, you can calculate the maximum aggregate size based on this NOW document and drive Rightsizes.
• The FAS2020 currently supports four shelves of fourteen drives each, plus twelve internal drives for a total of sixty-eight drives.
• I never got to the point of pushing our 2020′s performance limits while we had it, but in general, the more spindles you have, the faster. I suspect that the 2020′s performance might be hamstrung by it’s limited NVRAM (128MB with a single controller), but I can’t confirm that. Our 2050 has performed adequately as second-tier storage for two 3040s.

Updated: Fixed my math on the maximum aggregate sizes – I left out the 10% WAFL overhead!