Raspberry Pi 2B and SSD drive

[Ian Lepore]

On Sun, 2018-06-17 at 20:33 +0200, Per olof Ljungmark wrote:
> On 06/17/18 18:26, Warner Losh wrote:
> > 
> > On Sun, Jun 17, 2018, 7:46 AM Karl Denninger <karl at denninger.net> wrote:
> > 
> > > 
> > > On 6/17/2018 08:21, Per olof Ljungmark wrote:
> > > > 
> > > > FBSD 11.2-RC1
> > > > 
> > > > How can I make good use of a USB SSD drive connected to the Pi?
> > > > 
> > > > For instance, can I start from the SD card and then hand over everything
> > > > to the SSD drive? From googling it does look like it is possible.
> > > > 
> > > > Thanks!
> > > > 
> > > Yes, but....
> > > 
> > > The but being that it's still USB attached and won't be nearly as fast
> > > as you expect.
> > > 
> > Yes. You'll need a A20 based board or similar with built in SATA ports to
> > get good speed. The RPi are good cheap boards, but they aren't so good for
> > file servers or other applications needing high bandwidth.
> > 
> I am not after speed, I am after greater reliability than what the SD
> card can offer. The Pi will do duty as a simple SMTP server and I have
> already tested with the SD card only and speed is good enough.

I'm not sure why you think an sdcard is somehow unreliable. I ran an
smtp+pop+imap server with both the primary and backup "disks" being
sdcards for about 7 years, without a single glitch that entire time. I
recently replaced the whole server with one that has a builtin mSata
drive, but sdcard is still my backup solution for that machine since it
has a builtin slot.

At $work we ship products that use sdcards as their only storage
device, and many of those products have a nominal 20-year service life.
So far the longest that one has been in the field is 12 years, but we
have had zero sdcard failures (with the exception of one embarassing
incident where a whole batch of sdcards went bad in the first couple
months of use, apparently because somewhere in the supply chain a batch
of low-quality greymarket cards snuck in).

As to the basic question of how to boot an rpi from a usb drive, my
advice would be to have u-boot and ubldr.bin on an sdcard (just use the
standard download image), and keep the kernel and all other filesystems
on the usb drive. To make that work, there needs to be a "usb start"
command that happens in u-boot before ubldr.bin is launched, and you
need to "setenv loaderdev usb".

-- Ian