[Tutor] Mount size
Faulconer, Steven M.
STEVEN.M.FAULCONER at saic.com
Thu Oct 28 15:37:18 CEST 2004
Thanks for the response. Since the calls are not reliable for NFS mounts, is
there a pure python way of getting that information? We originally had a
system call that ran a df with some awk's and sed's to get what we need, but
we felt that had to be a way within python to do this. We can go back to
that method, but I'd really like a pure python way of reliably getting
available space on local and NFS mounted volumes.
If you or anyone else has any ideas, I'd love to hear them.
From: Danny Yoo [mailto:dyoo at hkn.eecs.berkeley.edu]
Sent: Wednesday, October 27, 2004 6:20 PM
To: Faulconer, Steven M.
Cc: tutor at python.org
Subject: Re: [Tutor] Mount size
On Wed, 27 Oct 2004, Faulconer, Steven M. wrote:
> We are having some issues getting reliable information for available
> disk space within Python programs. We are using os.statvfs to get the
> blocks free, but the numbers are not consistent between local and NFS
> mounted drives.
[some text cut]
> Given that f_bavail is the number of blocks available (non-superuser)
> I would assume that we could multiply that by f_bsize and then divide
> by 1 million (for megabytes) or 1 billion (gigabytes).
You may want to use f_frsize, not f_bsize. The underlying man page for
statvfs says the following about the tuple that we get back:
u_long f_bsize; /* preferred file system block
u_long f_frsize; /* fundamental filesystem block
(size if supported) */
fsblkcnt_t f_blocks; /* total # of blocks on file system
in units of f_frsize */
fsblkcnt_t f_bfree; /* total # of free blocks */
fsblkcnt_t f_bavail; /* # of free blocks avail to
fsfilcnt_t f_files; /* total # of file nodes (inodes) */
fsfilcnt_t f_ffree; /* total # of free file nodes */
fsfilcnt_t f_favail; /* # of inodes avail to
u_long f_fsid; /* file system id (dev for now) */
char f_basetype[FSTYPSZ]; /* target fs type name,
u_long f_flag; /* bit mask of flags */
u_long f_namemax; /* maximum file name length */
char f_fstr; /* file system specific string */
u_long f_filler; /* reserved for future expansion */
(Taken from Solaris 8 man page on statvfs)
The way that the docs make a distinction between the "preferred" and
"fundamental" block sizes is significant. Use 'f_frsize' instead, and you
should get better results.
There's also a section in the BUGS that says:
The values returned for f_files, f_ffree, and f_favail may
not be valid for NFS mounted file systems.
So be careful not to depends on those particular values on NFS-mounted
I hope this helps!
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