i386 Linux on USB pen drive

i386 Linux on USB pen drive

[Arik Funke]

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Hello together,

I am setting up a linux system to run on a USB memory stick. Currently I
am using kernel 2.6.7 and ext3 as filesystem. Can anybody tell me if
wear-leveling will be a problem with this system? Or should I rather use
a fs like jffs or jffs2? Is kernel 2.6.x ok?

Thanks a lot,
Arik

BTW: Could anybody please point me in the right direction if this is
off-topic in this mailing-list.
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Re: i386 Linux on USB pen drive

[Charles Manning]

On Saturday 25 September 2004 06:10, Arik Funke wrote:
> Hello together,
>
> I am setting up a linux system to run on a USB memory stick. Currently I
> am using kernel 2.6.7 and ext3 as filesystem. Can anybody tell me if
> wear-leveling will be a problem with this system? Or should I rather use
> a fs like jffs or jffs2? Is kernel 2.6.x ok?

This is very much like those threads one reads occasionally about Compact 
Flash.

All we really know about these devices is that they conform to USB mass 
storage. We don't really know what goes on inside them, but we can make some 
educated guesses :-).

Most likely, IMHO, these devices will be using a block swapping strategy like 
that used in SmartMedia. This does not do explicite wear levelling, but the 
block management does effect wear levelling.

The biggest source of problems with these devices, IMHO, is FAT corruption. I 
see you've taken steps too get rid of that. 

The flash file systems like JFFSx and YAFFS are really suited to raw flash 
(SmartMedia and XD cards and soldered down chips) , not USB Mass storage 
devices (which look like hard disks). Dave might not share my opinion on this.

-- CHarles

Re: i386 Linux on USB pen drive

[Arik Funke]

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Charles Manning wrote:
| Most likely, IMHO, these devices will be using a block swapping
strategy like
| that used in SmartMedia. This does not do explicite wear levelling,
but the
| block management does effect wear levelling.
|
| The biggest source of problems with these devices, IMHO, is FAT
corruption. I
| see you've taken steps too get rid of that.
|
| The flash file systems like JFFSx and YAFFS are really suited to raw
flash
| (SmartMedia and XD cards and soldered down chips) , not USB Mass storage
| devices (which look like hard disks). Dave might not share my opinion
on this.

If I understood you correctly I have done everything right without even
knowing about the possible technical traps? I do not need to worry about
dying sectors, etc. and ext3 was the right choice? Or should I chose a
journaling filesystem? (the system will run as minimal communication server)

As there seems to be extensibe knowledge here about linux on flash
devices, two other questions:
1. Is it correct to assume that systems on flash devices need to run
without swap partitions? (due to frequent writing on these)

2. Is there any easy advice which parts of the directory structure
should better not be mounted on the flash? Or in which directories in
the linux structure will typically occur frequent write accesses? (E.g.
log-files?)

Is there maybe a HOWTO or anything discussing linux on flash in general?
~ I guess these are fairly typical questions...

Cheers,
Arik
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