On 09/02/17 23:00, Christoph Moench-Tegeder wrote:
## Thomas Güttler (guettliml@xxxxxxxxxxxxxxxxxx):
Is running linux with postgres on eMMC a bad idea in general?
I'd say that running anything with a read-write load on eMMC will
end in pieces. It's ok to occasionally write something, but a mixed
load is not really what these things were designed for. The wear
leveling can be quite basic, you never know when it's gonna happen
(i.e. sudden power down can kill your filesystem - that's why disabling
journaling is not a very great idea), and if your device is "mostly
full" anyways, the wear leveling has not much space to redirect the
writes to. Remember that some of those chips are sold mostly by
price - that is, the hobbyist "embedded" devices get the cheapest
chips. A safer bet would be adding an external storage; some
64GB SATA SSDs are available for less than 50€ (perhaps it's better
not to go for the cheapest ones here, too).
I agree, but three additional comments. First, we've got a fair number
of RPis running their root filesystems on the internal SD-Card without
problems, but the one Odroid which runs an eMMC card failed a few weeks
ago. Second, a useful precaution is to put stuff which will be updated
on an external device, although the same longevity concerns apply if
it's Flash-based. Third, experience here suggests that reliability
/might/ be improved if you fully zero a device before partitioning it to
make absolutely sure that the internal controller has touched every block.
--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk
[Opinions above are the author's, not those of his employers or colleagues]
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