Raspberry Pi Forums

Can we look for a complete removal of dependency on SD card and instead have in-built memory (solid-state possibly). While a Class 10 SD card is reliable in general, but it still poses a fair amount of risk/dependency in a production system.

Comments / Suggestions are welcome.

Welcome the the Forums...

The answer to your basic question is...sort of. There is a version of the Pi called the Compute Module (CM). The CM has 4GB of eMMC "flash" memory on the board. However, that--plus the SoC and DRAM--is *all* that is on the borad. The CM is used with a carrier board that brings out whatever peripheral connections are wanted. Making a carrier board is non-trivial.

*All* other versions Pi have an SD card slot. With the Pi3B, you can set a One Time Programmable (OTB) bit that will permit it to boot from something other than the SD card. See the sticky thread at the top of the General forum for details and discussion. So, if you want to go with a conventional Pi and you want to boot from something other than an SD card, use that feature of the Pi3B or the new version of the Pi2B (the Pi2B2).

On types of memory... All modern memory, whether volatile or non-volatile is solid state. That has been true for at least 40 years. One could argue whether ferrite core memory is "solid state" or not, but it isn't an intrinsically electronic storage medium in any case. Non-solid state memory would be things like acoustic delay lines or CRT refresh systems and those haven't be used for many decades. One might debate the status of magnetic tape or disk (or some of their more exotic variants like the IBM Data Cell), but you're not going to attach either of those to the surface of a printed circuit board, especially not in millions of units per year with a retail price of not more than $35 each.

Perhaps if you could expand on just what you're looking for, a better discussion of what is, or is not, possible can ensue.

The advantage of using SD cards is that they are user replaceable. This means the system can easily be serviced if the flash storage fails or becomes corrupted, and you can easily change operating systems or functionality by swapping cards. While SD cards aren't necessarily the perfect solution (they have notoriously poor random I/O performance), they are preferable to built-in flash.

On board flash would fail at some point,
You can use USB or network boot with the Pi3,
No SD needed.

Older models can do similar with just a single boot file needed on the SD card.

HawaiianPi wrote:The advantage of using SD cards is that they are user replaceable. This means the system can easily be serviced if the flash storage fails or becomes corrupted, and you can easily change operating systems or functionality by swapping cards. While SD cards aren't necessarily the perfect solution (they have notoriously poor random I/O performance), they are preferable to built-in flash.

+1 !!!
The Pi should be "unbrickable", any kind of on-board storage might lose that.

Also you get to pick and choose the card based on your own requirements for speed, quality, size, and price.

Now a removable eMMC card (as the Odroid C2 has) would be nice.

I personally love that I can develop on one of my desktop PI3s/proto boards then swap the cars to a zero that is installed in a gadget/appliance/friends house with a quick card swap. Please don't take that away.

I'm with the OP as in my experience SD cards are not particularly reliable - made down to a price, I guess. Some higher quality on-board flash would be good.

james-at-lo-tech wrote:I'm with the OP as in my experience SD cards are not particularly reliable - made down to a price, I guess. Some higher quality on-board flash would be good.

The main advantage of SD cards is that if you get it wrong and end up with an unbootable Pi, you can take the card out and rewrite it or replace it with a working one.

Not so easy with onboard flash.

It's never been a problem with other embedded solutions eg OpenWRT. We just need a reset button to do (something). Or boot from SD card if present by preference.

james-at-lo-tech wrote:I'm with the OP as in my experience SD cards are not particularly reliable - made down to a price, I guess. Some higher quality on-board flash would be good.

Buy better quality SD cards. You get what you pay for.

Personally I've seen highest failure rates in the top branded cards. I don't have enough data to present any scientific information though, only enough experience to know that they are a weak point.

HawaiianPi wrote:

james-at-lo-tech wrote:I'm with the OP as in my experience SD cards are not particularly reliable - made down to a price, I guess. Some higher quality on-board flash would be good.

Buy better quality SD cards. You get what you pay for.

Again, I am with HawaiianPi over this.
My SD cards (mostly samsung) are all reliable.

james-at-lo-tech, are you sure you are shutting down the Pi cleanly every time?

The samsung evo+ is reasonably priced, performs well, and often recommended here.
16-32 GB gives you the most space for the money I think.

If the SD card is a weak point, surely that can be alleviated by multiple redundancy - buy lots of cards?

Fixing the memory on-board means when it breaks the whole thing's broke.
With interchangeable cards, it's only the card that's broke.

I'd still like to know what sort of non-solid state memory the OP thinks is available.

And for everyone who wants eMMC flash on a Pi, get a CM. CM1 now, CM3 "soon", or CM3-16 (NEC) probably some time in January.

Burngate wrote:If the SD card is a weak point, surely that can be alleviated by multiple redundancy - buy lots of cards?

Fixing the memory on-board means when it breaks the whole thing's broke.
With interchangeable cards, it's only the card that's broke.

+1

I've not had a single SDCard or microSD fail in eighteen months (after the firmware fixes were issued), so it's bound to be a thing of buying the right cards at the right price. I had one RPi with 346 days up time (terminated only by the sparky who replaced the broken and dangerous socket in our garage when he dropped the power).

W. H. Heydt wrote:I'd still like to know what sort of non-solid state memory the OP thinks is available.

Sure he is thiking at liquid state memory http://www.wired.co.uk/article/liquid-hard-drives
--
Jmp0

JumpZero wrote:

W. H. Heydt wrote:I'd still like to know what sort of non-solid state memory the OP thinks is available.

Sure he is thiking at liquid state memory http://www.wired.co.uk/article/liquid-hard-drives
--
Jmp0

Maybe...but it's not like that is an off the shelf, buy it by the millions right now technology. Let alone something cheap enough not to adversely affect the price of a Pi.

james-at-lo-tech wrote:Personally I've seen highest failure rates in the top branded cards. I don't have enough data to present any scientific information though, only enough experience to know that they are a weak point.

I have had a couple failures with Sandisk brand (in the past), but none from any other brand (PNY, Transcend, Lexar, Silicon Power, Samsung). We have a lot of SD and microSD cards in cameras, phones, tablets, computers, and a few Raspberry Pi models (Pi-B512, Pi2, Pi3, Pi-Zero).

So what is it that you consider "top branded" cards? And are you sure they were genuine? There are a LOT of fakes on ebay and other places.

To look at this a different way, I've used an SBC that has onboard NAND rather than SD card for the OS. To flash it you need to put a jumper on a certain pin to put it in the right mode then either use a Chrome extension that doesn't seem to work for everyone or an SDK that only runs on Linux and requires reading a fair bit of documentation to use. Neither of these are particularly user friendly. And when the flash fails there's probably no chance of recovering any data from it (you can't just plug it into another machine and attempt recovery) and there's no way to replace it.

For the majority of users the SD card is the easier approach, easy to write the image on all OSes, easy to swap etc. and for large scale commercial setups there's the CM (as has been mentioned already)

I guess I was an early adopter with the PI, and have used several versions to build a LAMP-server that then controls different items accessible over the internet. I have used them for remote switching on the heating, or a remote switchable extension cord, and even a specific solar collector (www.solarair.livotel.com).
Yet ALL of them seem to fail after a number of months (24/7), usually in about one year. Not one survived since start so far. In practice it ment I pretty much had to flash a card at the start of every winter for the heater.
I am still trying with a Raspberry 3 for the solar collector, and made it bootable from an USB SSD, and that is still working, but was installed only about a month or 3 ago; We'll see...
After all the tests with different brands it is fair to say the raspberry with an SD card is not suitable for an application that runs 24/7 for more then a few months. The cards become unbootable every time. Usually one cannot even re-flash them anymore. I came even to the point (I regret to say) that I am starting with the Onion Omega2+, to see if that works better. I cannot yet say it will be more reliable, hopefully it is, but is shows how desperate I am about the stability of the Raspberry SD combination...

Just make your SD card's boot and root file systems read only. Then there is next to no chance they will get corrupted.

Some thoughts on the subject:

The thing with common brands is that they are also the ones most commonly faked. And faked ones may suddenly fail, because they are fake , and only will appear to be working for a short while. Fakes can be bought from an outlet from which you don't expect to get them..

Flash (SD-cards) also survive a *lot* less write cycles than spinning rust media (hard-disks), if you study how SD-cards work you start to wonder how they manage to work at all.....
So I'm not at all surprised they conk out after using them hard for a year... They are NOT made for such uses.

Well made ones have much better flash controllers, and much better flash, and that makes a LOT of difference.

Any flash based medium will corrupt itself if you turn off its power when it is still doing something, it can survive such an event much less well than any hard disk system.

jan_paulussen wrote: ↑

Fri Dec 22, 2017 3:57 pm

Yet ALL of them seem to fail after a number of months (24/7), usually in about one year. Not one survived since start so far. In practice it ment I pretty much had to flash a card at the start of every winter for the heater.
...
After all the tests with different brands it is fair to say the raspberry with an SD card is not suitable for an application that runs 24/7 for more then a few months. The cards become unbootable every time.

I had my Pi2 running for well over a year 24/7 with continuous writes to the SD Card. The only reason I stopped using that setup was I re-purposed that Pi with a larger SD card. Similarly I've yet to see an issue on my Pi3s that run 24/7 but those SD cards have been swapped around a bit as different things get tested.

One thing that might contribute to SD card issues is having a poor power supply. If you're getting power issues that might lead to corruption on the SD card (Most of my Pis run off the various official PSUs).

jan_paulussen wrote: ↑

Fri Dec 22, 2017 3:57 pm

... Yet ALL of them seem to fail after a number of months (24/7), usually in about one year.

There are a a few options you could try.

SSD is a good choice, which you are trying now. Look for ones using MLC, rather than TLC or 3D NAND (SLC would be even better, but expensive).

Have you tried any of the High Endurance SD cards? They are designed for continuous operation.

Read only OS on the SD card, with any data you need to save stored elsewhere (local server or cloud based solution).

jan_paulussen wrote: ↑

Fri Dec 22, 2017 3:57 pm

. . . I came even to the point (I regret to say) that I am starting with the Onion Omega2+, to see if that works better. . . .

The Onion Omega2+ boots (OpenWRT) from flash then runs out of RAM so unless you're logging a large amount of data there shouldn't be flash endurance problems with it. If you use it with the SDcard then all write operations (e.g. data logging) could be to the SDcard and the OS in flash would be essentially read-only. If you use the Omega2+ system on module without their carrier board, be aware that power layout to the module is critical and frequently a source of frustration for new users.

That said, Tiny Core Linux for RPi does the same, that is run from RAM after boot, and the RPi is a far more capable computer which may or may not matter for your application. There are also means to run Raspbian from a read only filesystem on the SD card with a mountable R/W USB memory device. I personally haven't used either configuration, but there are thread on this bulletin board from people who have.

Not that it helps your situation, but I have a RPi Model B that's been running virtually non-stop for about 3 years on its original SDcard which suggests there may be something about your situation that is causing high failure rates. Considerations might include unstable power, large (by some standard) numbers of SDcard write operations, and/or extreme temperatures.