Originally Posted by
GullLars
I've asked the same question many times. It can be best illustrated by looking at Indilinx Barefoot drives.
You have the 32GB unit that can do roughly 200MB/s read and 100MB/s write, 15K IOPS read and 3K IOPS write, and only has 4 (or 8??) NAND chips on flash 4 channels, and the 256GB unit, wich COULD do 8 times the bandwidth by simply running 8 times the memory chips in parallell, only does 250MB/s read, 180MB/s write, 15K IOPS read, 3K IOPS write.
You can take 8x Barefoot 32GB in RAID-0 off a HBA like LSI 9211 and get roughlly 1400-1500MB/s read, 600-700MB/s write, 120K IOPS read, 24K IOPS write. This makes me think the higher capacity models of Indilinx Barefoot are a complete waste of flash modules, and it's clear the bottleneck is the SSD controller (maybe also the SATA 3Gbps interface for sequential reads on the higher capacities).
You could make a simple SATA 6Gbps SSD with 3x 32GB Barefoot drives and a cheap ROC (RAID-on-Chip) and use internal RAID-0 to get 550MB/s read, 250-300MB/s write, 45K IOPS read, 9K IOPS write, and 96GB capacity.
The same setup with 4x 32GB barefoot would perform 600MB/s read (or whatever the practical limit is), 350-400MB/s write, 60K IOPS read, 12K IOPS write, and have 128GB capacity. Such an SSD would wipe the floor with SandForce 100GB, C300 128GB, and x25-M 160GB, at least with regards to bandwidth and value. Even if you had to use a $100 ROC chip, you could still come in at $500.
Another interresting possibility is 3x x25-V in the same type of setup. ca 550MB/s read, 120-130MB/s write, 90K IOPS read, 30K IOPS write, 120GB capacity, $400 ROC included.
What would be awesome would be a native PCIe SSD with simelar caracteristics as SandForce SF-1500/1200 50/100GB minus the RAISE™, just with 3-4 controllers in internal RAID on the board. Files compressable to to ~20% of original size could be read and written at 2-3GB/s+... Not to mention random write about 90-100K IOPS (4K alligned).