Why do I feel like compact flash is more reliable than SSD ?

[Roland Smith]

On Thu, Dec 29, 2011 at 11:13:24PM -0800, UFS User wrote:

> I have run a lot of different FreeBSD systems off (fileservers, firewalls,
> routers, etc.) off of compact flash cards[1] and have never had a CF part
> fail.
> 
> Most of these were read-only mode, but some of them were left mounted 'rw'
> for years (with no swapping, of course).  The bottom line is, they never
> failed, and some were (and are) in the field for over 8 years now.
> 
> But everyone I know (including me) has had an SSD fail, usually with no
> explanation.

It seems that unlike disk drives, SMART doesn't really give you a warning with
SSDs.

But as a counterpoint, who hasn't ever had a harddrive fail? And there might
be some negativity bias [http://en.wikipedia.org/wiki/Negativity_bias] at work
here too.

> So is this just chance, or ... are CF cards really a lot more reliable than
> SSD ?

Although I've been looking at SSD's, I've held off for now because of cost and
small disk sizes. But concrete data is relatively scarce, probably due to the
fact that SSD's haven't been available _that_ long.

There are several studies available for harddisks, e.g. from google
[http://labs.google.com/papers/disk_failures.pdf] and Carnagie Mellon [http://www.usenix.org/events/fast07/tech/schroeder/schroeder_html/index.html].
Generally, more disks fail as they age.

But studies concerning SSD's seem to be almost nonexistant. The most interesting
inventarization I found was on Tom's Hardware
[http://www.tomshardware.com/reviews/ssd-reliability-failure-rate,2923.html].
Some interesting quotes covering the main points;

	Even though our data set is one-twentieth the size of previous studies on
	hard drives, our information starts to suggest that SLC-based SSDs are no more
	reliable than SAS and SATA hard drives.
	...
	Our data center survey exclusively covers Intel SSD failure rates because
	those are the drives that big businesses currently trust the most.
	...
	Should you be deterred from adopting a solid-state solution? So long as
	you protect your data through regular backups, which is imperative regardless
	of your preferred storage technology, then we don't see any reason to shy away
	from SSDs.

Currently SSD's are too small for my taste. But when that changes, I'll
seriously consider switching to an SSD with an equal sized HDD for nightly
backups.

Roland
-- 
R.F.Smith                                   http://www.xs4all.nl/~rsmith/
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