In article ,
HVB wrote:
...
Generally speaking, ATA and SATA drives are intended for desktop use
and although they may be designed in a similar (or even the same) way,
they are not subjected to the same testing regime or manufacturing
tolerances as Enterprise-class products.
...

No, wrong. Desktop-class drives are DESIGNED radically different from
Enterprise-class drives. This has been true for about a decade. The
last time SCSI and IDE drives were the same underlying drive with just
different interface boards was a long time ago. For the gory detail
of the massive differences between desktop-class and enterprise-class
drives, start by reading: "More than an Interface - SCSI versus ATA",
by Erik Riedel, Jim Dykes, and Dave Anderson, available at a web
search near you.

There is a huge difference in cost, performance characteristics
(tradeoff between capacity and speed), and reliability between
desktop-class and enterprise-class drives. In a nutshell, one could
say: desktop class drives are very cheap, have very high capacity, but
they are slow, and unreliable (both in overall livetime, and also in
their resilience to problems, like they don't like to deal with
vibration). If you look how they are engineered differently (single
combined servo/datapath processor, meaning unable to servo the head
while writing, slower spindles, weaker actuators, fewer air filters,
larger platters, lightweight but weaker frames), this all makes sense.

Little of the difference between desktop-class and enterprise-class
drives is about testing. The story is not that you start with
fundamentally the same drive, and the ones that pass the test get a
SCSI board bolted on and are sold for $$$, while the ones that fail
the test get an ATA board bolted to it and are sold for $.
Internally, the design is radically different.

Now, what is true: While all FC/SCSI drives are enterprise-class
drives, not all ATA/SATA drives are desktop-class drives. About 2
years ago, some manufacturers (names withheld to protect the guilty)
started a trend of selling purported enterprise-class drives with ATA
interfaces. Today, there are quite a few supposedly enterprise-class
drives being sold with SATA interfaces. Unfortunately, I haved talked
to experts in the field (names withheld), which have performed a
teardown analysis on some (but not all!) of these ATA/SATA
enterprise-class drives, and they find that they are built like
desktop-class drives; this was particularly true of the early models.
The following rule of thumb seems to hold in many cases: If something
is nearly as cheap (in $ per byte) as a desktop-class drive, it is
unlikely to be a reliable enterprise-class drive. You do get what you
pay for. If you want a free lunch, look elsewhere.

Now, naturally you can take low-reliability drives, and using
RAID-style techniques built high-reliability disk systems out of them.
The industry has been doing this since the late 70s or early 80s (even
though the buzzword RAID was only coined in 1989). Given the
extremely large capacity of modern drives, and their dropping
reliability (the actual rate of loss of bytes is increasing, because
the capacity is increasing much faster than the reliability), more and
more exotic RAID techniques are required these days (a dumb RAID 5
with a large group, without scrubbing and/or failure prediction is
unlikely to cut it any longer). Whether the building of RAID arrays
by amateurs using off-the-shelf commodity components and inexpensive
disks is a good value, everyone has to determine for themselves,
making a tradeoff between cost of goods, cost of effort for building a
disk system, and value of the data = cost of data loss.

Disclaimer: My employer (which shall remain nameless) does not
manufacture disk drives, but uses many of them, and I do storage
systems for a living. But at home I use a mix of enterprise-class
drives in a RAID configuration (for stuff I care about, like baby
pictures) and cheap drives bought at low-end computer stores (for
stuff downloaded from the net and for backups).

--
The address in the header is invalid for obvious reasons. Please
reconstruct the address from the information below (look for _).
Ralph Becker-Szendy