On Tue, 25 Jul 2006, David Masover wrote:
Horst H. von Brand wrote:
18GiB = 18 million KiB, you do have a point there. But 40 million files on
that, with some space to spare, just doesn't add up.
if you have 18 million KiB and each file is a single block (512 Bytes = 0.5 Kib)
then assuming zero overhead you could fit 18 Million KiB / 0.5 KiB = 36 Million
files on the drive.
thus being scheptical about 40 million files on a 18G drive.
this is only possible if you are abel to have multiple files per 512 byte block.
David Lang
Right, ok...
Here's a quick check of my box. I've explicitly stated which root-level
directories to search, to avoid nfs mounts, chrooted OSes, and virtual
filesystems like /proc and /sys.
elite ~ # find /bin/ /boot/ /dev/ /emul/ /etc/ /home /lib32 /lib64 /opt
/root /sbin /tmp /usr /var -type f -size 1 | wc -l
246127
According to the "find" manpage:
-size n[bckw]
File uses n units of space. The units are 512-byte blocks by
default or if `b' follows n, bytes if `c' follows n, kilobytes
if `k' follows n, or 2-byte words if `w' follows n. The size
does not count indirect blocks, but it does count blocks in
sparse files that are not actually allocated.
And I certainly didn't plan it that way. And this is my desktop box,
and I'm just one user. Most of the space is taken up by movies.
And yet, I have almost 250k files at the moment whose size is less than
512 bytes. And this is a normal usage pattern. It's not hard to
imagine something prone to creating lots of tiny files, combined with
thousands of users, easily hitting some 40 mil files -- and since none
of them are movies, it could fit in 18 gigs.
I mean, just for fun:
elite ~ # find /bin/ /boot/ /dev/ /emul/ /etc/ /home /lib32 /lib64 /opt
/root /sbin /tmp /usr /var | wc -l
866160
It may not be a good idea, but it's possible. And one of the larger
reasons it's not a good idea is that most filesystems can't handle it.
Kind of like how BitTorrent is a very bad idea on dialup, but a very
good idea on broadband.
