Dear Ashish,
The ls uses st_size while du uses st_blocks.
try using the ls -ls it will give you both the o/p's .
Thanks
Manish
On Fri, Aug 5, 2011 at 7:45 AM, Ashish Sangwan <ashishsangwan2@xxxxxxxxx> wrote:
I write 1 program to create sparse file which contains alternate empty blocks and data blocks. For example block1=empty, block2=data, block3=empty .....
#define BLOCK_SIZE 4096 void *buf; int main(int argc, char **argv) { buf=malloc(512); memset(buf,"a",512); int fd=0; int i; int sector_per_block=BLOCK_SIZE/512; int block_count=4; if(argc !=2 ){ printf("Wrong usage\n USAGE: program absolute_path_to_write\n"); _exit(-1); } fd=open(argv[1],O_RDWR | O_CREAT,0666); if(fd <= 0){ printf("file open failed\n"); _exit(0); } while(block_count > 0){ lseek(fd,BLOCK_SIZE,SEEK_CUR); block_count--; for(i=0;i<sector_per_block;i++) write(fd,buf,512); block_count--; } close(fd); return 0; }Suppose, I create a new_sparse_file using this above code.
When I run this program, on ext3 FS with block size 4KB, ls -lh shows size of new_sparse_file as 16KB, while du -h shows 8 kb, which, I think is correct.
On xfs, block size of 4kb, ls -lh shows 16KB but du -h shows 12kb.
Why are there different kinds of behavior?If I increase the block_count to be written so that a 200MB file is created, on XFS du -h shows 187MB and on EXT3 it shows 101MB.
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