[kwlug-disc] OT: SSD disks?

[Chris Irwin]

On Wed, Nov 11, 2015 at 11:45:59PM +0000, B.S. wrote:
> The real world scenario is - can one, and which, trust these
> newfangled SSD drives? And, aside from the is the price different
> worth it, especially vis a vis the purported increase in speed
> (anecdotal evidence here says no), is the price and capacity
> differential over spinning drives worth it / are they more/less
> reliable than said spinning drives?

If we're counting anecdotes, I'll put mine on record and say that I will
never, ever have (or willingly use interactively) a system based on an
mechanical HDD again. Hell, even my remove VM (on linode) is backed
entirely by SSDs now.

SSDs are Faster - yes you might not "notice" anything but boot times
when switching to an SSD, but you do notice switching back to an HDD
once you're used to it.

Also, considering my primary machine is now a laptop:

* No moving parts. Spinning a disk at 5400 or 7200 RPM, then skimming
  the heads just barely off the surface in a device *that moves* is just
  the craziest idea ever. Back when I was a student, the amount of free
  pizza I got for replacing dead laptop hard drives was obscene. When
  was the last time I had to worry about head parking or drop sensors?

* Much reduced power consumption on my laptop (yeah, I couldn't put it
  aside :)

HDDs are still great for bulk data storage, simply due to price per GB.
That's backups, home movies, flac cd rips, videos, etc.

> (Putting aside the eco/power consumption elements, here. And never
> mind that avoiding single point of failure means you're going to have
> multiple/redundant storage, of whatever technology used.)

I treat all drives like they are going to fail any moment, also
regadless of technology used. This happens. A lot. I have a stack of
dead/dying hard drives at home. I only have one dead ssd so far. I
currently own and use seven SSDs, and down to seven in-use hard drives,
plus my two external backup hard drives.

I currently put more trust in SSDs than HDDs. Almost all my HDDs are
raid1 pairs because I consider their failures to be exceedingly common
(especially any drives purchased in the year or so following the
Thailand flooding). All my SSDs are individual drives that I can recover
from backups. I'm prepared, but not actively expecting it.

> They note that warnings of imminent problems are well exposed, giving
> one time to address, to at least as good a level as spinning disks.
> Spinning or not, ignore such warnings at your peril.

Yes and no. I believe the larger studies (like that by google) found
that SMART errors were a reliable forcast for failure, but the lack of
SMART errors can not be assumed to indicate a healthy drive.

I've had hard drives fail without warning, and gracefully migrated from
drives with errors.

My failed SSD had no errors before death.

> People were backing up to optical media for said permanent storage
> that turned out not to be. (Optical media having dyes, and dyes fade
> ...) Along the way, the amount of data to be archived seems to have
> grown exponentially - thus some of the reason for the growth to the TB
> drives we see available today. Given the low SSD capacities vis a vis
> these TB drives, they do not seem to fit this purpose. Thus whether or
> not they retain their data, when we know the more cost effective
> spinning drives do, isn't so important to me.

The advantages of SSDs (seek times, throughput, etc) do not apply to to
sitting on a shelf, but all it's negatives (mainly capacity & price) do.
You just can't beat hard drives right now, regardless of where we fall
on SSD reliability.

Archival SSD devices are something only SSD manufacturers need to
consider right now.

Regardless of storage medium, you'll want a way to verify data, even if
the drive "works". A filesystem that can do checksums on it's own would
be helpful...

> Thus, I guess, cloud growth as off-site backup/archival storage. Which
> has its own excessive costs, and risks.

I currently back up to 2x 2TB hard drives, which are swapped weekly and
dragged to work.  If disaster strikes, my recovery estimates involve
"drive to work", "buy hard drive on the way home", and "SATA/Disk
transfer speeds". I can do the recovery with just a LiveUSB and a
replacement drive.

With cloud backup, I also have to factor in slower transfer speeds,
bandwidth caps (300GB/mo would take me three months to restore all my
data), and possibly a *client* I need to install and configure first,
which might mean *not* a LiveUSB.

For a "normal" user, where a failed hard drive means a magical new one
gets installed with a fresh copy of Windows/OSX, cloud backups make a
lot more sense.

-- 
Chris Irwin

email:   chris at chrisirwin.ca
 xmpp:   chris at chrisirwin.ca
  web: https://chrisirwin.ca