I might be a bit disillusioned by the past, but I don't trust MLC NAND or
consumer SSD drives. The reason for this is significant first hand experience
testing MLC NAND flash and MicroSDHC drives (many years ago, at least 5 years
ago I think). The other reason is because I've seen the failure rate of SSD
drives first hand.
The problem at one time was usually the result of power failures and not the
flash itself. Currently there are at least some Samsung, Crucial, Sandisk,
and Mushkin drives that seem to be good enough. I personally still don't
trust NAND in general or SSD relative to traditional spinning disks. However
statistically speaking from a non-emotional perspective the SSD drives we're
shipping today have a decent track record.
I never had a NAND flash card (MicroSDHC) or USB flash drive last more than
six months under real world desktop/altpop use conditions (again, five years
ago I did extensive testing over probably a year or two utilizing all the
best flash drives and MicroSDHC cards available at the time). The failure
rate becomes most apparent when you put USB flash drives and MicroSDHC
(tested other types of drive as well, like mini spinning compact flash disks
from IBM, also high failure rates) cards to normal hard disk-type use. Even
with read-only filesystems similar to what Luke (lkcl) described where you
only booted in a read/write mode to apply updates resulted in a quick demise,
including when utilizing raid for redundancy. Yes- I put MicroSDHC cards into
a redundant raid setup. It sort of works, but cards fail quickly enough to be
a serious hindrance. Restoring the redundancy / recovering once a card failed
ended up taking up a lot of time.
So the situation here sounds really bad. It sounds like a really bad design.
However I think the issues can be overcome with SLC and/or a good USB to SATA
adapter combined with a decent SSD drive. At the time there weren't any
MicroSD SLC cards that I could get my hands on easily to test nor USB SLC
flash drives (humorously there was a drive with the word SLC in it, but it
wasn't SLC, it was MLC, very confusing). It would appear you can get up to
8GB SLC MicroSD cards currently and 64GB SLC USB flash drives.
I should also note that full disk encryption may have also increased the risk
of failure with prior testing. This is not something most people are
utilizing even today. So it is difficult to say for sure that you can't get
more than six months out of a normal MLC based MicroSDHC card under less
severe conditions.
