PCie ssds vs raid?

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I am new to the
whole SSD thing, but I don't understand how the following
works?

I need to be very specific for this
question to make sense.

1 x LSI MegaRAID SAS
9361-8i 570$
8 x Ultrastar SSD800MH MLC 200GB
8x1450 = 11.600$
Total cost:
12.170$

Expected
performance in RAID 0:
read: 140x8 = 1.120.000
IOPS
write: 100x8 = 800.000 IOPS />space: 200x8 =
1.6TB

On the other hand we
have:

ioDrive2 Duo 1.2TB SLC
Total
cost: 28.500$ />

Expected performance: />read: 580.000 IOPS />write: 535.000 IOPS />space:
1.2TB

One will say: RAID 0 will
fail. But the truth is ioDrive2 Duo can also fail, so you have to buy 2 and
RAID 1 them.

I understand the
different between SLC and MLC (performance and durability), but the Ultrastar drives
seems really solid and unless you torment them, they won't
die.

All in all, what is wrong with my
calculations? Why people buy those PCIe cards and they don't build arrays of drives?
It's more simple to manage, but it costs more than
double?

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class="normal">Answer

We use
both FusionIO kit and lots of top-end SSDs, and we have seen failures in both but with
the FusionIO we've not had anything that caused data loss, RAID 0
will kill your data one day, it's not an 'if', it's a
'when'.

Now onto your calculations, the FusionIO
stats are about what we see too but are you sure that LSI card can actually deliver 1.1m
IOPS? I'm guessing you'd have to split the disks across all channels to get close to
that?

We buy the PCIe cards because they're
really consistent, there's less 'parts' and complexity involved, they're not pretending
to be a spinny-disk so the latency is lower. Yes they can be more expensive (we perhaps
get better pricing on those to be honest) but for what we use them for they're better
overall value - that said we use SSDs in R10, I'd never consider a R0
setup.