On 2006-01-28, Bengt Richter <[EMAIL PROTECTED]> wrote: >>Because it isn't really writing the zeros. You can make these >>files all day long and not run out of disk space, because this >>kind of file doesn't take very many blocks. The blocks that >>were never written are virtual blocks, inasmuch as read() at >>that location will cause the filesystem to return a block of NULs. > > I wonder if it will also "write" virtual blocks when it gets real > zero blocks to write from a user, or even with file system copy utils?
No, in my experience none of the Linux filesystems do that. It's easy enough to test: $ dd if=/dev/zero of=zeros bs=64k count=1024 1024+0 records in 1024+0 records out $ ls -l zeros -rw-r--r-- 1 grante users 67108864 Jan 28 14:49 zeros $ du -h zeros 65M zeros In my book that's 64MB not 65MB, but that's an argument for another day. -- Grant Edwards grante Yow! It's the land of at DONNY AND MARIE as promised visi.com in TV GUIDE! -- http://mail.python.org/mailman/listinfo/python-list