Reclaiming "hidden" capacity on outboard USB hard drive

ubuntu at ubuntu at
Thu Jun 15 20:36:48 UTC 2006

Peter N. Spotts wrote:
> On Thu, 15 Jun 2006 12:19:18 -0400
> "Mark Warner" <markwarner1954 at> wrote:
>> Peter N. Spotts wrote:
>>> Folks,
>>> Over the past month and a half or so, I've gotten helpful advice on
>>> ensuring that my Ubuntu installation (now 6.06) reads from and
>>> writes to my outboard USB drive (Maxtor 300gb). I'm looking to
>>> close the book on the troubles I had by reclaiming what appears to
>>> be "missing" capacity.
>>> To briefly recap: I had been using the drive as a backup. During the
>>> switch from another distro to Ubuntu, I lost the ability to read to
>>> and write to the drive, so I was advised to treat it like a new
>>> drive, formatting it in ext3, setting up new partitions, etc.
>>> Ultimately, that got me back in business. However...
>>> 1. Fdisk -l shows 300 gb of gross capacity.
>>> 2. Gkrellm shows 295 gb total and 274 free (meaning at least 21 gb
>>> used, depending on whether you like Fdisk or Gkrellm statistics).
>>> 3. duh -h shows that the files it can detect on the drive are using
>>> only 6 gb of space.
>>> So it appears that I've got gobs of gigs missing. Is it possible to
>>> reclaim them? Or are they destined to spin furiously forever like
>>> some forlorn tourists on a renegade ride at Diskneyland?
>> Which is closer to what you're expecting, 6G used or 21/26G used?
>> What does gparted say?
>> As for the 300/295G reporting discrepancy, don't worry about it. Very
>> common, especially with large drives. It's just the way it is.
> Hi Mike,
> Gparted shows 279 gb with 10 used. After using du -h, I expected to
> have perhaps 293 or 294 gb left. I suspect that the 21+/- has files in
> it; it's about what I has before I had my initial troubles with getting
> Ubuntu to read the disk. As gparted sees it, I've got a drive that's
> only 279 gb in size, of which it sees 10 gb as taken. So somewhere, I
> would expect some 21 gb more in total space, of which the 21 might be
> filled with files...

It's probably the reserved blocks.  With ext3, by default, a certain
percentage of the filesystem is reserved for root's use.  This is so an
individual user can't completely hose a system by filling up the disk.

man tune2fs

You can use tune2fs to unreserve the area, since it's a usb drive, it
really isn't needed.

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