Perma-pim

[Pleng]

I understand that installing apps to the NAND is to be 'frowned upon' and not encouraged, but will there be anything to phsically stop people installing apps to the NAND?

The reason I ask is that I will have a number of SD Cards which I will be swapping into and out of the Pandora. On the other hand, I'd like to use the Pandora as my main PIM, should such software be produced.

Now I'm no expert on how such software works but presumably such software would either need to reside in NAND, or on an SD card which is always in the same slot, as presumably a wake-up call is scheduled in the Pandora which would then wake the system up and resume the PIM application. If, on wake up, that application is on an SD card residing in a different slot to where it came from (or, even worse, on an SD card which is not even in the Pandora) then would errors not occur, and the alarm/meeting/reminder fail to sound/show on screen.

 

[Squidge]

The NAND will always be read/write, as that is required for software updates. It is likely that the included application installers will not support installing to nand, but you will be able to do it yourself via the command line or similar.

 

[surt]

As I understand it, it is constantly rewriting the NAND that'll kill it and being non-replaceable, that is a bad thing.

I don't reckon a once-off write to install your PIM to NAND should be at all problematic, but if you plan to store your data there, and keep it up to date, it possibly could be.

If you are going to leave your P powered on then it should be possible for you to store your application and data in RAM so you don't need to read/write NAND or SD, but then you risk data loss if the battery dies.

A good thing about the P is that it has two SD slots, so you can leave one always in and swap out the other as necessary.

 

[Pleng]

Thanks for the feedback, Squidge

 

[TaG]

A good thing about the P is that it has two SD slots, so you can leave one always in and swap out the other as necessary.

That's my view too.

 

[Tom`]

I've seen a lot of concern over writing to the NAND due to the possibility of causing it to wear out, and I'm sure this can in theory happen if you used it for swap or something, but ... ever since Windows Mobile 5.0, which came out a few years ago, all Windows-based smartphones and portable devices have used NAND for storage (previously only the OS was stored on NAND and the device's RAM was partitioned between storage and program memory). Now, I'm well aware that Microsoft doesn't always make great decisions, but I've heard no such concerns with any of those devices (people mostly complained about it being slower, IIRC.) So is this a different kind of NAND, or are there other concerns?

 

[Chip]

So is this a different kind of NAND, or are there other concerns?
No, the danger of NAND failure due to overuse is blown way out of proportion. The risk of damage only becomes significant ofter many, many years of frequent use.

Really, the main reason we're discouraging people from using the NAND for non-system storage is to ensure that somebody doesn't fill it up and cause a system update to fail due to insufficient space. Plus, with SD cards being so cheap, it's just good practice to keep your system and applications separate.

But Squidge tells the truth - we're not preventing you from using the NAND for whatever you want. We're just suggesting that you don't. If you're going to use a PIM app every day and want it on your NAND so that it's always acessible, then have at it.

 

[Chero]

I don't reckon a once-off write to install your PIM to NAND should be at all problematic, but if you plan to store your data there, and keep it up to date, it possibly could be.

No, it won't.
I've been using a zaurus, PIM storage on NAND, lots of reflashes, installing apps, removing apps, ... . NAND still acts like it did in the beginning. No errors on file system checks, no issues with anything.
Check the numbers for the lifetime of NAND. If you plan to write every sector of your NAND about 200 times a day then you might really wear it out in about 3 years ... .
If you use it for normal stuff, the NAND will live longer than the device will (I suppose there will be something new in about 15 years ...).
Just don't use your NAND to create a swapfile ...

Edit : Chip was first, read his post again and you'll understand.

Chero.

 

[Squidge]

I just think of it this way: Everything has a MTBF, so, considering that, why use fixed non-replaceable memory storage when you have two slots for removable memory storage? Those card holders are very much likely to last much longer than the internal nand

Chero: Errors on nand are typically not reported to the user (It's behind the scenes). If a block becomes bad, it's typically remapped to another completely automatically. If you get a fair number of them you may notice your free space decreases even though the used space is the same, but other than that, most errors are completely invisible to the user unless you use specialist applications. Typical NAND usage is at least 100,000 writes per block multiplied by the wear levelling counters (for example, if you continuously wrote to block zero, and you had 1000 blocks free, that "At least 100,000" would turn into "At least 100,000,000"). Apologies if you already knew this btw.

 

[Chero]

I just think of it this way: Everything has a MTBF, so, considering that, why use fixed non-replaceable memory storage when you have two slots for removable memory storage? Those card holders are very much likely to last much longer than the internal nand

Chero: Errors on nand are typically not reported to the user (It's behind the scenes). If a block becomes bad, it's typically remapped to another completely automatically. If you get a fair number of them you may notice your free space decreases even though the used space is the same, but other than that, most errors are completely invisible to the user unless you use specialist applications. Typical NAND usage is at least 100,000 writes per block multiplied by the wear levelling counters (for example, if you continuously wrote to block zero, and you had 1000 blocks free, that "At least 100,000" would turn into "At least 100,000,000"). Apologies if you already knew this btw.

I knew, but they don't die easily. It is very important to check bad blocks on a zaurus when doing a nand-restore. In that case the remapping doesn't always work ...
My only point was that people should not panic - in about 3 months - and think their nand will die because the system has been upgraded for 5 times already ...

 

[Squidge]

Yep, we should expect at least 10,000 updates before there starts being problems.

 

[devhace]

Uh oh. I was expecting updates to come every 5 seconds forever. Well I have no interest in this project anymore.

 

[atomicthumbs]

Just don't put a swapfile there.

 

[Tor]

I have yet to hear about any NAND failure from any Nokia tablet user, and the 770s have been used since 2005. The N800 has been used since Jan. 2006. These devices have their operating system as well as all user files (music, photos, docs etc.) in NAND, out of the box.
I've used my own device for nearly 2 years now, and I'm using it daily - I never go anywhere without it.

I'm not much worried about NAND overuse.

 

[mahousaru]

One thing to be careful of when working out flash life is how much of it is full. As far as I know the wear level mechanism does not move existing data, but just data written. So if the partition is permanently occupied 80% by the OS (pulled out of a hat), then mtbf should be calculated for the area left for dynamic data usage.

Of course updating the OS should change that.

 

[VRAndy]

I would assume that even if you have a couple of bad sectors a decade from now Linux should just be able to identify and avoid them.

 

[efegea]

I would assume that even if you have a couple of bad sectors a decade from now Linux should just be able to identify and avoid them.

Yes, and these sectors will be unused anyway...who will use 100% of the NAND?

 

[SOLGarion]

Yes, and these sectors will be unused anyway...who will use 100% of the NAND?

Yes, and why would we ever need more than 64k RAM? oh wait...

 

[efegea]

Yes, and these sectors will be unused anyway...who will use 100% of the NAND?

Yes, and why would we ever need more than 64k RAM? oh wait...


You know that's not what I meant.. I meant that that nobody will fill all the 536870912 bytes of the NAND, I'm not saying that 512MB is enough and nobody will use all of it...of course there will be always demand of more space, but what I said is that there always will be unused sectors, becuase nobody will fill all of them.

Of course someone can copy an iso file to the NAND accidentally and get the NAND filled, with 0 free bytes, but that's a punctual case.

 

[Squidge]

Considering the NAND is meant for the OS, nobody should ever use 100% of the NAND. If they do, it may have other consequences rather than just what you state about the bad block remapping (OS updates failing being one of them).