获取稀疏文件真实大小

转至 http://stackoverflow.com/questions/3211999/sparse-file-usage-in-python

问题

5 down vote favorite Please login or register to vote for this post. (click on this box to dismiss)

I'm creating sparse files in python as follows: >>> f = open('testfile', 'ab') >>> f.truncate(1024000) >>> f.close() when the file is done, it takes up 0 disk space, but its inode size is set to my truncated value (1000K): igor47@piglet:~/test$ ls -lh testfile -rw-r--r-- 1 igor47 igor47 1000K 2010-07-09 04:02 testfile igor47@piglet:~/test$ du -hs testfile 0 testfile how do i get the file's real space usage inside python? the stat call returns the file's apparent size, and i have no idea how else to get the real usage other than to read the entire file (it may become quite large) >>> os.stat('testfile').st_size 1024000

答案

up vote 6 down vote accepted

>>> os.stat('testfile').st_blocks*512 0 Tadaa :) st_blocks is the number of 512-byte blocks actually allocated to the file. Note thatst_blocks is not guaranteed to be present in all operating systems, but those that support sparse files generally do. share | improve this answer edited Jul 9 '10 at 11:27 answered Jul 9 '10 at 11:20 wump 1,883 4 12

2   st_blksize provides actual block size of the filesystem. Generally speaking it doesn't have to be 512 bytes. –  SilentGhost Jul 9 '10 at 11:33 1   I was confused for a moment, but that's not true.st_blksize is the "preferred" file system block size. st_blocks is guaranteed to be in blocks of 512 bytes (see the manpage). –  wump Jul 9 '10 at 12:49   This particular solution was working this morning, but after i've changed the server machine it suddenly stopped working. Do you have any advice on that? –  Hgeg Oct 8 at 0:42