[talk] SD cards for Pi?

Charles Sprickman spork at bway.net
Sun Nov 19 20:13:13 EST 2017

Thanks for the info, Brian - 

> On Nov 19, 2017, at 6:13 PM, Brian Reynolds <nycbug-talk at reynolds.users.panix.com> wrote:


> In particular I have a Raspberry Pi 2 model B running LibreELEC
> hanging off my TV.  I use it to watch various videos I download from
> the Internet to the SD card used to boot the RPi.  I frequently fill
> and empty this card.  Downloading new videos while simultaneously
> viewing other videos can tax both the IO system and CPU on the RPi.

Is this a SanDisk card? I imagine that it sees a fair amount of writes.

> I find that the most important factor for SD card stability with the
> RPi is power supply quality.  If your power supply is flaky, or on the
> low end of the recommended power range you can expect trouble.  Since
> switching to 2.5A power supplies from good vendors (Adafruit, Micro
> Center) I haven't had trouble.

I found that out early on, the included power supply in my bundle was
total junk. I’m now using of all things an extra iPhone cube that seems 
to work well.  I think it’s 1A or 1.5A.  I see some people recommend 2A
but I have no peripherals...

> Charles Sprickman wrote:
>> So two questions:
>> - At a local Walgreens or Staples, what???s a decent SD card?  I
>> know nothing of these things.
> I tend to use SanDisk SDHC or microSD cards, mostly because that's
> what I use for my photography.  Cards with Class 10 or U3 ratings
> should be fast enough.

Are you aware of any link between the write speed (“class”) and the
flash endurance?

> At last month's Photo Plus Expo I asked the representative at the
> SanDisk booth about which card to use for SBC filesystems.  He hadn't
> realized that anyone was using SD cards that way, but suggested that I
> look for cards used for surveillance cameras on their website.
> Unfortunately their website is big on flashy presentation, and low on
> technical content.

Good to know.

>> - Is there any tweaking I should have done to FreeBSD to make it not
>> write excessively to the card (I did not have swap enabled)?
> .ike has good ideas on changes you could make.

Done, and I think I had a very crappy card as well (Maxell).

> I have a lightly loaded original Raspberry Pi Model B (256MB RAM)
> running FreeBSD 10.2-STABLE that I use for fiddling around.  Without
> my making changes, it has /tmp as mfs in /etc/fstab.  I assume .ike's
> recommendations are for more recent releases.
> I'll eventually update the release on this RPi, and I may get back to
> my experiments in booting FreeBSD off of a hard disk instead of the SD
> card.  On older models you need an SD card to hold the FAT filesystem,
> but root (and other partitions) can be on a USB drive.  I got this far
> a while ago.  On the Raspberry Pi 3 model B there is beta support for
> hard disk, or network booting without a SD card.  I have not tried
> this with FreeBSD yet.

I’m looking for something - either more Pis or beaglebones or whatever
the current hot/cheap thing is - to put at some client sites.  When we
take over something where we’re managing some of their internal stuff
a generic “unix box” inside that can tunnel out, serve up some splash
page for a captive portal, relay some logs out, or a ton of other things
would be handy.  I’d have more buy-in if I could grab something for
$50 or so. As far as the hardware goes, storage is the most worrisome.
Have you had any luck with sticking “real” SSDs in a USB enclosure
and hooking that up to a Pi?  At least they have some published
endurance specs.  Not sure if you can pull SMART data over USB



> -- 
> Brian Reynolds                   | "It's just like flying a spaceship.
> reynolds at panix.com               |  You push some buttons and see
> https://www.panix.com/~reynolds/ |  what happens." -- Zapp Brannigan
> NAR# 54438                       |  
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