Next Writable address

Hi,

I am having one question,

How the hard disk will come to know the Next Writable Address.

When we issue write/read command, we specify data and number of bytes
to read/write. But how the hard disk will come to know the address, it
has to write to /read from specify sector. Who will specify(which
software layer) to the hard disk, this sector address.

Thanks

Guru

The FAT contains the list of used and unused clusters. If you are appending
to a file or creating a new file, the file system will scan the FAT
searching for the first unused cluster.
--
Jeff Richards
MS MVP (Windows - Shell/User)
wrote in message
ps.com...
Hi,

I am having one question,

How the hard disk will come to know the Next Writable Address.

When we issue write/read command, we specify data and number of bytes
to read/write. But how the hard disk will come to know the address, it
has to write to /read from specify sector. Who will specify(which
software layer) to the hard disk, this sector address.

Thanks

Guru

Hi,

just I do have one more doubt:
Think I will write one file, assume that it will be written to 500th
sector.
if I again write another file, where that file will be written .
whether to 501th sector or any other sector number.

Thanks
-guru



Jeff Richards wrote:
The FAT contains the list of used and unused clusters. If you are appending
to a file or creating a new file, the file system will scan the FAT
searching for the first unused cluster.
--
Jeff Richards
MS MVP (Windows - Shell/User)
wrote in message
ps.com...
Hi,

I am having one question,

How the hard disk will come to know the Next Writable Address.

When we issue write/read command, we specify data and number of bytes
to read/write. But how the hard disk will come to know the address, it
has to write to /read from specify sector. Who will specify(which
software layer) to the hard disk, this sector address.

Thanks

Guru

On 7 Jun 2006 00:18:34 -0700, "guru" wrote:

just I do have one more doubt:
Think I will write one file, assume that it will be written to 500th
sector.
if I again write another file, where that file will be written .
whether to 501th sector or any other sector number.

This is a difficult question to answer conclusively as there could be
many factors which might affect the determination of the next disk
sector allocated for recording the contents of a file. But this is the
responsibility of the operating system so application software and the
developers of such need not be concerned with these details.

Thanks
-guru

I am intrigued by your choice of username. If you want to read about
the FAT32 filesystem search for FATGEN103.PDF; it is an excellent
reference for this filesystem.

--
Steven

hi
Thanks steven, I will go through that document.

and also the username is my first name. My full name is Gururaja.B O

regards
-guru


Steven Saunderson wrote:
On 7 Jun 2006 00:18:34 -0700, "guru" wrote:

just I do have one more doubt:
Think I will write one file, assume that it will be written to 500th
sector.
if I again write another file, where that file will be written .
whether to 501th sector or any other sector number.

This is a difficult question to answer conclusively as there could be
many factors which might affect the determination of the next disk
sector allocated for recording the contents of a file. But this is the
responsibility of the operating system so application software and the
developers of such need not be concerned with these details.

Thanks
-guru

I am intrigued by your choice of username. If you want to read about
the FAT32 filesystem search for FATGEN103.PDF; it is an excellent
reference for this filesystem.

--
Steven

On 7 Jun 2006 02:36:14 -0700, "guru" wrote:

Thanks steven, I will go through that document.

Good to hear. The help files from a Win32 SDK might also be interesting
as they describe how to access files and what details are supported by
and available from the operating system. Perhaps somebody else here can
provide a suitable link.

--
Steven

The file system accesses the disk by clusters, not sectors.

The cluster number used for any new file or for any addition to an existing
file is the next free cluster in the FAT. It could be the next sequential
cluster number if the disk is recently formatted, but after a few deletions
it could be anything at all.
--
Jeff Richards
MS MVP (Windows - Shell/User)
"guru" wrote in message
ups.com...
Hi,

just I do have one more doubt:
Think I will write one file, assume that it will be written to 500th
sector.
if I again write another file, where that file will be written .
whether to 501th sector or any other sector number.