[poll; updated] eMMC vs. uSD; modular eMMC

[sebt3]

They will become faster as well.

That is one of the reasons I would want the SD over the eMMC. If everything were static, then eMMC is better. But things are constantly changing and upgrading, thus I would prefer SD.

The uSD card might become faster over time, the pyra data-bus between the card reader and the CPU will not though, so you might not gain from speedier cards

 

[Grench]

They will become faster as well.

That is one of the reasons I would want the SD over the eMMC. If everything were static, then eMMC is better. But things are constantly changing and upgrading, thus I would prefer SD.

The uSD card might become faster over time, the pyra data-bus between the card reader and the CPU will not though, so you might not gain from speedier cards

Yes. SD cards have outstripped the bus on the Pandora for a long time now. This is an inevitable event in the progress of electronics.

 

[God Ginrai]

What i worry the most about is that ED is boned the day nand starts failing when it shouldnt and its soldered to the board.

Don't know why you guys are so paranoid about this. Has failing NAND yet to be a noteworthy problem with Pandora? Why was this never a talking point before?

It was a talking point before: When the Pandora was being developed. NAND failure and bad system updates bricking your system were the 2 reasons why EvilDragon and Craig wanted to make sure that we had bootable SD so that in the case that either happens, the Pandora isn't just a brick.

The reason I'm suggesting microSD is so that we don't have to worry about our 2 SD device becoming effectively a 1 SD device because we have to reserve one SD for the OS.

-God Ginrai

 

[Natsu]

I think I want to keep it simple by using a micro SD card.

 

[TrashyMG]

^ eMMC is even more simple. As long as the memory isn't from some shady company, It's most likely been through proper testing and such. 
 

And you don't have to worry about mechanical damage to the socket. which I believe physically damaging a socket is more common than getting a bad eMMC module that has been through proper testing.

While speeds of SD cards have got higher, it still depends on the bus speed.

 

[God Ginrai]

And you don't have to worry about mechanical damage to the socket. which I believe physically damaging a socket is more common than getting a bad eMMC module that has been through proper testing.

Yes, but that would only be through repeated insertions. Since this would be fore the OS, (and preferably under the battery) the average user is unlikely to change it out often.

Thus, the reliability becomes almost the same. With the exception that when the microSD card dies, you can replace it. Which is something you can't do with the eMMC.

-God Ginrai

 

[TrashyMG]

Yes, but that would only be through repeated insertions. Since this would be fore the OS, (and preferably under the battery) the average user is unlikely to change it out often. Thus, the reliability becomes almost the same. With the exception that when the microSD card dies, you can replace it. Which is something you can't do with the eMMC. -God Ginrai

Well how I see it in both cases you will need to send it for repair and both cases it would require a skilled soldering repair. However I see the eMMC as the safer solution, seeing how most of these sockets are not intended for repeated insertions and even if they were they're still mechanical in nature with tiny fragile parts and people generally find a way to break things. Well you say that most people won't be taking the SD card out much, however I think the nature of a Pandora/Pyra device it will be used a lot.

 

[God Ginrai]

Yes, but that would only be through repeated insertions. Since this would be fore the OS, (and preferably under the battery) the average user is unlikely to change it out often. Thus, the reliability becomes almost the same. With the exception that when the microSD card dies, you can replace it. Which is something you can't do with the eMMC. -God Ginrai

Well how I see it in both cases you will need to send it for repair and both cases it would require a skilled soldering repair. However I see the eMMC as the safer solution, seeing how most of these sockets are not intended for repeated insertions and even if they were they're still mechanical in nature with tiny fragile parts and people generally find a way to break things. Well you say that most people won't be taking the SD card out much, however I think the nature of a Pandora/Pyra device it will be used a lot.

I don't think you understood what I said. The average user would not be making repeated insertions, so the only thing that could go bad is the microSD itself. You do not need soldering experience to replace that.

-God Ginrai

 

[TrashyMG]

^ Well I don't think you understand my concerns with the SDCard issue.. I don't care about the SDCard... Sure it can be replaced, it's the socket I have issues with.

I take the MicroSD card out of my phone quite a bit.. more than I like honestly, because it's quicker in some cases to move files around on my laptop and I find myself sans USB cable a lot.. Luckily my phone is insured..

This is a niche device, people will do things outside of the intended average use.

Shouldn't repair costs for EvilDragon/Dragonbox be a factor?

 

[Natsu]

^ Well I don't think you understand my concerns with the SDCard issue.. I don't care about the SDCard... Sure it can be replaced, it's the socket I have issues with.

I take the MicroSD card out of my phone quite a bit.. more than I like honestly, because it's quicker in some cases to move files around on my laptop and I find myself sans USB cable a lot.. Luckily my phone is insured..

This is a niche device, people will do things outside of the intended average use.

You would have 3 memory card slots in total.

 

[TrashyMG]

And? People will still take out the internal one more than they should.

 

[Askarus]

They will become faster as well.

That is one of the reasons I would want the SD over the eMMC. If everything were static, then eMMC is better. But things are constantly changing and upgrading, thus I would prefer SD.

The uSD card might become faster over time, the pyra data-bus between the card reader and the CPU will not though, so you might not gain from speedier cards

1: But then it doesn't make a difference in the end speed wise but we can use larger micro SD cards then.

2: Also if eMMC does not provide the maximum speed Pyra can deal with then we might get some more speed after faster Cards come out.

In the end if Micro SD will reach the maximum speed Pyra can get there is no drawback if we use micro SD.

 

[comradekingu]

And your response to how that is the slowest option available?

Still fast enough. 100MB/s is not bad -- you can read the entire Pandora NAND in 5 seconds at that speed. I doubt the HDD in your desktop computer is that fast, and it will certainly have worse latency. If you really need more speed, make a RAM drive. Extra speed is always nice, but not if it means we're stuck with a fixed size. In any case the maximal difference in speed is a factor of two, and I doubt it would even be that much if we would get an eMMC today with a reasonable price/size/speed trade-off.

100MB/s is for sequential reads, burst presumably, because just because the bus speed can sustain it, doesn't also mean the controller can.  Besides we are talking about OS use. I dont have a HDD attached to my desktop, but the SSD i have in my desktop can do Random 4 KB Reads: up to 41,000 IOPS


Random 4 KB Writes: up to 80,000 IOPS in very start comparison to the <1000 on even queue depth 1 on the best uSD.  Educate yourself http://en.wikipedia.org/wiki/IOPS and dont assume.

Besides, if you dont want to go about getting a uSD based on random chance, and get utterly laughable performance, like 5 Iops, which is more the norm than the exception, you are limited to up to 32GB on that toshiba card.

 

[Natsu]

And? People will still take out the internal one more than they should.

They are going go through the trouble of pulling out the internal memory card morethan they should when there's 1 to 2 much more accessible ones right in the front?

 

[TrashyMG]

Yup. When they want to switch out the primary os. Upgrade to a larger SD card.. etc.

 

[Natsu]

Yup. When they want to switch out the primary os. Upgrade to a larger SD card.. etc.

Front SD card transfer.So,they upgrade every second? lol

 

[Grench]

Yup. When they want to switch out the primary os. Upgrade to a larger SD card.. etc.

Seriously? You're planning to get out the screwdrivers on a whim and pop the microSD card out to switch the primary OS when you could simply boot your alternatives with the SD card?

Treat it just as if it were eMMC with the exception of IFF you want to change the physical card for a new one. I could see doing it once a year or two to increase the card size or speed - which are features not faults.

Otherwise, if you're loading an OS, boot from SD and install it on the microSD.

The, 'I pull the microSD on my phone more than I like to copy files' is an invalid argument. That is the only physical media that your phone takes.

Real use scenario, the microSD is going to be inserted and stay put for >=99% of the device life, with the 1% exceptions being changed for hardware (not OS) upgrades. OS upgrades would happen just like they do now - from an SD card.

 

[TrashyMG]

Generally it's placed in places like the battery compartment that doesn't need a screwdriver.

 

[Exophase]

Probably almost no one would go through the trouble of upgrading the internal microSD card to get more storage or speed when they could upgrade one of their external full SD cards instead. Sure, you could max out all of them, but the max storage on the microSD card will be at best half of what the full SD can give so you'd be missing out on being able to increase your total storage by under 25%. That's pretty whatever.

In my mind, the ability to more cheaply replace a broken microSD card is the only compelling advantage for the user after the device has been purchased (so ignoring any advantage in manufacturing regarding cost or ease of programming). But it's only an advantage if the eMMC actually dies before something else does and the unit is no longer under warranty, and you haven't yet replaced the device with something newer and better. Given how many other failure points there are on the device it doesn't seem worth that much to mitigate one of them unless it's known to be less reliable, which it isn't.

 

[God Ginrai]

Generally it's placed in places like the battery compartment that doesn't need a screwdriver.

Yes, but like I said: the average user will not be switching the card that often.

Many users don't even switch the OS, and at least half of those who would be so inclined will just use the bootable SD slot on the outside of the device. The subset of users who would actually frequent this internal slot is actually quite small.

-God Ginrai