RAM vs. Internal Flash vs. Flash SD Cards

[lny98]

This may be a stupid question but just want to make sure:

1. Can applications can be installed and run from the SD? Is it just like any other removable file system on a *ix box?

2. I assume the firmware is on the internal flash (256MB on the 800 if I read correctly). Can the system boot off off of an external card?

I ask this second question as have been reading about OS2008 vs. 2007, and since 800 comes with 2007, can I experiment with 2008 on a flash card>

3. Can flash be used to truly suppliment interal RAM by acting as swap space, so truly large programs can be run?

Just curious..

Thanks again in advance.

[TA-t3]

1. In principle, yes. Out of the box, no. This is because the SD cards are automatically mounted 'noexec'. This is possible to change though.

2. Yes, about the firmware. And yes, about booting off a card. There are several threads here on ITT with how-to's. (And included in this is the possibility to run applications from the card tpo, no strings attached). If you can experiment with OS2008 on a card I don't know, I mean technically it can be done but it's a question of someone testing this and setting up a system for the rest of us.

3. You can add swap space, yes. On the N800 the control panel application will let you add up to 128MB swap on the internal card.

[anidel]

About 3. Yes you can have the swap file on the external flash SD cards, but I would not suggest you to do so as the lifetime of the card itself would be greatly shortened.

[TA-t3]

I've seen that claimed before, but is there any real evidence for it? Obviously there will be some writing to the card, more so when it uses more swap, but as the writing is wear-levelled all over the card it wouldn't be any worse than any other kind of writing. And less so the larger the card is.

[sevo]

For one, it does not affect the life of the card or the data validity - cell wear merely decreases the capacity, as worn-out cells are mapped out by the controller inside the card.

With wear-leveling, 100000 cycle lifetime per cell, and cards becoming obsolete by size and speed within two or three years, we need not really worry about swap - it would take several years of normal use to wear a gigabyte off a card.

Sevo