Re: O_DIRECT

[Devel <devel@integra-sc.it>]

Thanks a lot for your answare.
So if i would write information on a partition without a fs i have to write additional information to "retrive" the first one.
Do you know some readable material about o project about that?


Il Wed, 21 Jul 2004 09:52:15 -0700
Shesha Sreenivasamurthy <shesha@inostor.com> scrisse:

> Usually what you do is, partition the disk, create filesystem and read 
> or write files.
>   Reading and writing is without a filesystem.
>    Assume you have maintained some superblock information of your own 
> driver say last 512 bytes you have designated as superblock. You can 
> seek to that position and read the last 512 bytes which is meaningful 
> only to you. Note that I am read/writing raw bytes not any file. 
> Therefore you can read/write without a filesystem and even without any 
> partition,
> 
> -Shesha
> 
> 
> Devel wrote:
> 
> >Hi all,
> >how i can write data on a partition without a filesystem??
> >
> >Saluti Carlo!
> >
> >Il Tue, 20 Jul 2004 20:48:24 +0200
> >bert hubert <ahu@ds9a.nl> scrisse:
> >
> >  
> >
> >>On Tue, Jul 20, 2004 at 10:27:57AM -0700, Shesha Sreenivasamurthy wrote:
> >>    
> >>
> >>>I am having trouble with O_DIRECT. Trying to read or write from a block 
> >>>device partition.
> >>>
> >>>1. Can O_DIRECT be used on a plain block device partition say 
> >>>"/dev/sda11" without having a filesystem on it.
> >>>      
> >>>
> >>As fas as I know, yes, but be aware that O_DIRECT requires page aligned
> >>addresses! (an integral of 4096 on most systems).
> >>
> >>    
> >>
> >>>2. If no file system is created then what should be the softblock size. 
> >>>I am using the IOCTL "BLKBSZGET". Is this correct?
> >>>      
> >>>
> >>No idea what you mean - but see above about the aligned addresses.
> >>
> >>    
> >>
> >>>3. Can we use SEEK_END with O_DIRECT on a partition without filesystem.
> >>>      
> >>>
> >>I see no reason why not. Good luck!
> >>
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> >>
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