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-   Nokia N900 (https://talk.maemo.org/forumdisplay.php?f=44)
-   -   N900 Specifications (https://talk.maemo.org/showthread.php?t=31005)

patstew 2009-09-19 23:50

Re: N900 Specifications
 
Quote:

Originally Posted by GeneralAntilles (Post 324351)
As I've said before, the port is USB OTG. All of the hardware is there.

Is this definitely the case? The reason I ask is that looking at http://mos.futurenet.com/techradar/c..._12-420-90.jpg and http://en.wikipedia.org/wiki/File:Types-usb_new.svg it looks like the N900 has a micro-B socket. USB-OTG devices are required to have a micro-AB socket (a square one without the bevelled corners). If it doesn't take micro-A plugs, then either it doesn't support host mode, or it doesn't comply to standards, or wikipedia is wrong. http://en.wikipedia.org/wiki/Univers...-AB_Socket_OTG

texaslabrat 2009-09-19 23:56

Re: N900 Specifications
 
Quote:

Originally Posted by patstew (Post 330019)
Is this definitely the case? The reason I ask is that looking at http://mos.futurenet.com/techradar/c..._12-420-90.jpg and http://en.wikipedia.org/wiki/File:Types-usb_new.svg it looks like the N900 has a micro-B socket. USB-OTG devices are required to have a micro-AB socket (a square one without the bevelled corners). If it doesn't take micro-A plugs, then either it doesn't support host mode, or it doesn't comply to standards, or wikipedia is wrong. http://en.wikipedia.org/wiki/Univers...-AB_Socket_OTG

http://focus.ti.com/general/docs/wtb...emplateId=6123


as for standards (or failure to adhere strictly to them)...just get one of these:
http://www.buy.com/retail/product.as...ingid=41883616

You can also pick up a battery-driven powered usb hub to complete the ensemble ;)

lma 2009-09-20 08:09

Re: N900 Specifications
 
Quote:

Originally Posted by GeneralAntilles (Post 329918)
Actually, ext3 is better for flash than having to repair the filesystem every time you run out of power. The journalling is a much smaller burden than fscking the whole fs on boot. So, no, you're mistaken.

If ext2 & ext3 are the only choices I'd pick ext2 for the internal flash device (microSD cards that will be very cheap to replace by the time they are out of warranty are a different matter).

Running out of power should be an exceptional event, while the journalling is active the entire time the filesystem is mounted. While it's on, every time you change a single bit on the fs the system will have to re-write at least two entire eraseblocks on the flash (one for the journal, one for the actual filesystem data/metadata, depending on the mount options used). Wear-levelling or not, that seems too excessive for my liking.

The main issue IMHO is handling an interactive e2fsck when things go pear shaped (but ext3 doesn't eliminate the need for that completely either).

GeneralAntilles 2009-09-20 15:19

Re: N900 Specifications
 
Quote:

Originally Posted by lma (Post 330143)
Running out of power should be an exceptional event, while the journalling is active the entire time the filesystem is mounted. While it's on, every time you change a single bit on the fs the system will have to re-write at least two entire eraseblocks on the flash (one for the journal, one for the actual filesystem data/metadata, depending on the mount options used). Wear-levelling or not, that seems too excessive for my liking.

This has been discussed endlessly on #maemo, and much smarter people than myself preferred ext3 (including Nokia, it appears). Observation of flash memory survival rates (nearly 100% in what I've observed) seems to bear this out.

I'll stick to ext3, thanks.

lma 2009-09-20 15:58

Re: N900 Specifications
 
Quote:

Originally Posted by GeneralAntilles (Post 330238)
This has been discussed endlessly on #maemo, and much smarter people than myself preferred ext3 (including Nokia, it appears).

Well, Nokia's criteria (eg reduced support costs) may not necessarily coincide with mine (device longevity, especially past the warranty period) while both are valid individually.

Quote:

Observation of flash memory survival rates (nearly 100% in what I've observed) seems to bear this out.
Survival over what period and usage pattern? Keep in mind that flash writes impact the entire block device (not partition), so having things like swap, journal, .ash_history etc on the same chip have a cumulative wear effect.

BTW, there was some speculation that there's an extra (faster?) memory device in the RX-51 specifically for swap use, but I've lost track - was that ever confirmed either way? If there is, it could also be used to store the ext3 journal.

GeneralAntilles 2009-09-20 16:13

Re: N900 Specifications
 
Quote:

Originally Posted by lma (Post 330250)
Survival over what period and usage pattern? Keep in mind that flash writes impact the entire block device (not partition), so having things like swap, journal, .ash_history etc on the same chip have a cumulative wear effect.

My own internal 4GB SDHC that I've been using since mid-2007 to boot from and for swap and dozens of other people's similar arrangements on both N800s and N810s.

Quote:

Originally Posted by lma (Post 330250)
BTW, there was some speculation that there's an extra (faster?) memory device in the RX-51 specifically for swap use, but I've lost track - was that ever confirmed either way? If there is, it could also be used to store the ext3 journal.

There's not.

attila77 2009-09-20 16:25

Re: N900 Specifications
 
Quote:

Originally Posted by lma (Post 330250)
Survival over what period and usage pattern? Keep in mind that flash writes impact the entire block device (not partition), so having things like swap, journal, .ash_history etc on the same chip have a cumulative wear effect.

Actually, it IS better to have all these on one big device, as the wear is then spread across more flash blocks, unless you plan on introducing more chips with different technologies (=higher cost + more space + higher complexity).

Anyway, if this was a real problem, we'd be flooded with N810 users with dead internal cards by now (as the N810 is swapping on a 2GB flash device = 16x shorter life span than the N900 on equal tech and number of writes).

vinc17 2009-09-20 17:05

Re: N900 Specifications
 
Quote:

Originally Posted by attila77 (Post 330268)
Anyway, if this was a real problem, we'd be flooded with N810 users with dead internal cards by now (as the N810 is swapping on a 2GB flash device = 16x shorter life span than the N900 on equal tech and number of writes).

Not all users enabled swap space (I didn't), and when it is enabled, I wonder whether it is intensively used in practice.

Bratag 2009-09-20 17:06

Re: N900 Specifications
 
Quote:

Originally Posted by GeneralAntilles (Post 330238)
This has been discussed endlessly on #maemo, and much smarter people than myself preferred ext3 (including Nokia, it appears). Observation of flash memory survival rates (nearly 100% in what I've observed) seems to bear this out.

I'll stick to ext3, thanks.

ext3 has been shown to be the superior FS many times. This is a pretty good writeup on why. The article specifically mentions is lower power consumption. Always handy in a mobile device.

http://en.wikipedia.org/wiki/Ext3

attila77 2009-09-20 18:51

Re: N900 Specifications
 
Quote:

Originally Posted by vinc17 (Post 330281)
Not all users enabled swap space (I didn't), and when it is enabled, I wonder whether it is intensively used in practice.

Folks, please, once and for all, let the system worry about flash wear, it's more than capable of doing it, don't burden yourself with it.

As for swap usage, it will definitively be used, Linux likes to keep memory empty for cache and buffers, so if you have something that isn't too active, it will end up on the swap sooner or later.


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