[Soekris] Choosing Compact flash (Was: Memory upgrade)

[Pontus Pihlgren]

Trevor Talbot skrev:
> On Dec 17, 2007, at 8:59 PM, Iustin Pop wrote:
>
>   
>> On Mon, Dec 17, 2007 at 11:28:51PM +0100, Pontus wrote:
>>     
>
>   
>>> Oh, that sounds a bit discouraging. Isn't CF just a variant of the IDE
>>> bus, and should therefore be able to reach speeds of 33 - 133 MB/s
>>> depending on the controller. I realize that a caveat in the OpenBSD
>>> driver could slow things down, but all the way to 2MB/s ? I'm not 
>>> saying
>>> you are wrong, I'm just surprised. Have you done some benchmarks?
>>>       
>> FWIW, on a 5501 with DMA enabled and on Linux, using a SanDisk
>> SDCFX3-2048 (and indeed multi-sector):
>>
>> # dd if=/dev/hda1 of=/dev/null bs=128k iflag=direct
>> 377+1 records in
>> 377+1 records out
>> 49512960 bytes (50 MB) copied, 6.80798 seconds, 7.3 MB/s
>>     
>
> Flash is not very fast in general. Spinning disks are much faster at 
> sequential reads.
>
> The performance gain you always hear about with flash is actually the 
> random access speed, because solid-state media doesn't have seek times.
>   
(I'm sort of straying away from the original discussion now, tell me if 
I should mark this OT)

I've always thought that do be a bit odd, not that seek times are 
better, but that it speeds has to be slower just because it is flash. I 
understand that one single flash chip will have its speed limitation, 
but by grouping multiple chips together and reading from them in 
parallel(like a raid-0), that should give a big boost in performance.

I guess that is what's done in the fusion-io card:
http://www.fusionio.com/

(a little less droid speak: http://www.tgdaily.com/content/view/34065/135/)

It is a bit pricey, to say the least, but fast.

/Pontus.