Re: New filesystem for Linux

[Eric Dumazet <dada1@cosmosbay.com>]

Grzegorz Kulewski a écrit :
> Hi,
> 
> On Thu, 2 Nov 2006, Mikulas Patocka wrote:
>> As my PhD thesis, I am designing and writing a filesystem, and it's 
>> now in a state that it can be released. You can download it from 
>> http://artax.karlin.mff.cuni.cz/~mikulas/spadfs/
> 
> "Disk that can atomically write one sector (512 bytes) so that the sector
> contains either old or new content in case of crash."
> 
> Well, maybe I am completly wrong but as far as I understand no disk 
> currently will provide such requirement. Disks can have (after halted 
> write):
> - old data,
> - new data,
> - nothing (unreadable sector - result of not full write and disk 
> internal checksum failute for that sector, happens especially often if 
> you have frequent power outages).
> 

I believe some vendors have such devices. Mikulas called them 'disk', but it's 
in fact a (disk(s), controler, ram, battery)

Some controlers are even able to write into flash memory the un-written data 
when/if the battery/power is about to fail. When power goes up, controler can 
finaly do the writes on disks.


> And possibly some broken drives may also return you something that they 
> think is good data but really is not (shouldn't happen since both disks 
> and cables should be protected by checksums, but hey... you can never be 
> absolutely sure especially on very big storages).
> 
> So... isn't this making your filesystem a little flawed in design?

Well... even RAM can fail :) In this case isnt linux flawed in design ?