MicroSD Card Raid Plugin Module

1 cost vs speed vs size

1.1 Speed

12 Gbps = 1.5 GB/s

15 Gpbs = 1.875 GB/s

25 FPS 4096 x 2304 raw uncompressed 12 bit video daterate: 353.9 MB/s

50 FPS 4096 x 2304 raw uncompressed 12 bit video daterate: 707.8 MB/s

300 FPS 1920 x 1080 raw uncompressed 12 bit video daterate: 933.1 MB/s

100 FPS 4096 x 2304 raw uncompressed 12 bit video daterate: 1,415.6 MB/s

132 FPS 4096 x 2304 raw uncompressed 12 bit video daterate: 1,868.6 MB/s

300 FPS 4096 x 2304 raw uncompressed 10 bit video daterate: 3,538.9 MB/s

1.2 Cost

Prices evaluated March 2017:

If we filter out micro sd cards that have advertized write speed above 90MB/s the prices start at 0.50€/GB, pro brands are in the 0.60€/GB - 0.80€/GB ballpark.

2.5" SSDs with advertized write speeds of 450+MB/s start at around 0.25€/GB - 0.30€/GB

1.8" SSDs offer only very few models with 450+MB/s write speeds to choose from and prices are around 0.80€/GB - 1.90€/GB

M.2 SSDs connected over PCIe 3.0 x4 offering 1500+MB/s writespeed cost 0.40€/GB - 0.70€/GB and are the smallest and fastest option.

Conclusion: Using just 5 micro sd cards in a raid gives roughly the same combined speed as using one 2.5" SSD. In this configuration the SSD is less than half the price per GB as the micro SD raid.

When using 32 micro sd cards in the raid it would require roughly 7x 2.5" SSDs in a raid to match the same speed resulting in roughly 7 times the volume of the micro sd card raid

1.3 Size

2.5" SSD: 70 x 100mm

1.8" SSD: 54 x 78mm

One micro SD card: 11 x 15mm

6x3 cards with small gap between cards and space to insert them plus an 23x23mm FPGA would require roughly the space of 64 x 104 mm (just slightly higher as the current 57.15mm that dual plugin modules occupy. Different layouts of cards are of course possible.

2 Concept

Dual Plugin Slot Module with total of 12 - 15 Gbps input

32 micro sd card slots with 16 cards on each PCB side:

3 Research & Notes

Manually selecting how many cards are used for increasing speed and how many are used for writing copies/backups would be very convenient.