[Discuss] SSD drives vs. Mechanical drives

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

Jerry Feldman wrote:
> I have seen some competing posts on other forums
> SSD drives are certainly lighter and faster than mechanical hard drives.

Lighter, yes. Faster, not necessarily. Flash chips are faster for random
reads, certainly, but they're slower for sustained writes. You need a
lot of "spindles" to beat rotating media for sustained write speeds.
That's why SSDs are RAID0 devices inside their shells.

> The comment on Windows Boston that has no figures to back up his claim
> is that the SSD drives actually are less power efficient than mechanical
> hard drives because of their additional reliance on the CPU. And
> certainly SSD drives are more expensive.

The guy making that claim is ignorant of how SATA works. It's DMA.
There's no CPU involved with I/O regardless of the physical medium
inside the shell. Therefore, CPU load has no bearing on power efficiency.

In real-world operation, SSDs are about the same as HDDs when it comes
to power consumption. No mechanical parts is helpful, and reads are
cheap, but writes are expensive when it comes to power consumption. It
all tends to balance out for typical, day to day operation but more
specific applications like database journals that are all writes all the
time may skew power consumption measurements.

-- 
Rich P.