Re: Is it good for a PDA fs?

[Hans Reiser <reiser@namesys.com>]

Oleg Drokin wrote:

>Hello!
>
>On Sat, Jun 22, 2002 at 09:50:33PM +0400, Hans Reiser wrote:
>  
>
>>>faster.  The tail merging might save space, but I would like to see
>>>a study of its effects on the longevity of compact flash.
>>>I think, but could be mistaken, than you want JFFS or JFFS2.
>>>      
>>>
>>I also have a sharp zaurus with 256M CF......
>>Currently the CF uses VFAT, yes?
>>I bet it has the same wear issues, and no space savings....
>>    
>>
>
>CF is different story. They fight level of wearing in underlying layer.
>
Meaning that they hide it in the device driver, and the FS does not need 
to be aware of it?

>And on high level they emulate IDE.
>Zaurus also have compact flash memory directly accessible by CPU, that
>one can be access via MTD devices in Linux. There you can actually
>control wering by yourself. But reiserfs (v3) is not very suited for that
>JFFS & JFFS2 do.
>
>And you can format CF with reiserfs without any problems
>But do not expect that windows or digital cameras would understand
>that ;)
>Also - in conjunctions with PDAs - reiserfs is quite memory (RAM) hungry,
>so using it on 32M ram box is somewhat questionable.
>
>And static 32M journal (that's 13% off your CF size, btw)
>
Our journal resizing patch is waiting for the next pre1 to go in, yes?

Regardless of all of this, it really would not surprise me if a 
filesystem design for CFs does a better job than we do at CFs.....

It is so annoying that it is taking so long for 2.4.19.....  I respect 
it, and it is probably the right thing for the users, but our 
performance is suffering a lot for the lack of these patches in the 
mainstream kernel.....

>
>  
>
>>The zaurus has a non-standard kernel though, and it is based off of some 
>>rather old release (2.4.4?).  You would want to apply their kernel 
>>extensions to 2.4.18 or later I think  before using reiserfs....  If you 
>>do so, and get it working, let me know, the only reason I haven't used 
>>reiserfs on my CF is that I don't know where to get a recent kernel with 
>>their (presumably useful to the PDA) extensions....
>>    
>>
>
>Building ARM kernels is easy.
>I always build kernels for my ARM toys myself.
>
>and I bet that Zaurus kernel is based off some -rmk kernel with
>may be minor patches (sources of these should be available at Sharp
>of course).
>So getting (making) new kernel should be trivial.
>
I think I probably care more about downloading and trying the latest 
kalendar than installing a new kernel on it.;-)   It is nice to have ssh 
running on it now....   After our July 11 DARPA presentation though I 
will recompile the kernel, and maybe try reiserfs on an MMC, and test 
how the user interface and docs are for journal relocation/resizing.....

>Especially if they use some decent bootloader that allows to have
>several kernels.
>
>  
>


-- 
Hans