[Discuss] SSD drives vs. Mechanical drives

[richard.pieri at gmail.com (Richard Pieri)]

Bill Bogstad wrote:
> And why does it matter that flash chips are slow?   The question is whether
> SATA connected SSDs are slow.  The first 500Gbyte SSD that I looked at

What do you think SATA connected SSDs are? They're banks of flash chips
with a RAID controller and some DRAM cache. Just as RAID 0 with two
spindles is ~twice as fast as a single spindle, RAID 0 with two flash
chips is ~twice as fast as a single flash chip. Stack up enough flash
chips and sure, you'll get performance that's better than a single
rotating platter.

> (Samsung 840 EVO MZ-7TE500BW) claims a >500 Mbyte/sec sequential
> read/write speed.   Lower capacity SSDs (fewer chips for internal RAID0)

Samsung claims "UP TO" 500 Mbyte/sec sequential read/write speed. Actual
values for that model fluctuate wildly:

http://ssd.userbenchmark.com/SpeedTest/1519/Samsung-SSD-840-EVO-500GB


> Newegg claims same Samsung SSD has the an active power consumption of
> 0.24 Watts.   Here's some testing of a number of Samsung SSDs for
> power consumption:

It's not the watts. It's the watt-hours. A device that consumes 50% more
power than another but operates 75% faster is the more efficient of the
two. It consumes more watts -- joules per second -- but does so over a
shorter span. More watts but fewer watt-hours. So, like I wrote, it
depends on your usage but in general SSDs are about the same as HDDs in
general use.

-- 
Rich P.