Free space reported

replica9000 · 12-03-2010, 09:21 AM

I have a partition which is just about full, and added a new HDD for more space. I decided to try partitionmanager for KDE when I noticed the reported free space was wrong.

partitionmanager reports free space on /dev/sda3 as 61.61GiB.
http://www.replica9000.bizland.com/l...rtitionman.png
I though maybe the program was wrong, being it's the first time I've used it.

Dolphin reports the free space as 1.0Gib
http://www.replica9000.bizland.com/l...dolphin001.png
This seems to be accurate. I tried to copy a 1.4GiB file and it failed.

So I decided to see what gparted reports, which I've used plenty of times. gparted reports 47.14GiB free.
http://www.replica9000.bizland.com/l...ts/gparted.png

Since Dolphin seems to be reporting the correct free space left, where are these partition managers getting their number from? I even tried parted without the frontends.

Code:

parted -ms /dev/sda unit GiB print free
BYT;
/dev/sda:932GiB:scsi:512:512:msdos:ATA WDC WD10EACS-00D;
1:0.00GiB:7.45GiB:7.45GiB:ext3::boot;
2:7.45GiB:9.32GiB:1.86GiB:linux-swap(v1)::;
3:9.32GiB:932GiB:922GiB:ext3::;
1:932GiB:932GiB:0.00GiB:free;

All 4 report space in GiB, yet the numbers seem to be very different. Why is this?

lazlow · 12-03-2010, 09:57 AM

Just a guess, but by default ext3 reserves 5% of the disk space for system use only. For the disk that the OS is actually on this is done to prevent the system from being unable to boot properly when it runs out of space. For non OS disks it is just wasted. You can shut off this reserve but only do it for non OS disks(storage area).

replica9000 · 12-04-2010, 12:15 AM

Ok that makes sense. I can see why Dolphin would report less than the partition managers. But still partitionmanager and gparted still report to completely different numbers.

So the command "tune2fs -m 0 /dev/sda3" should be safe to use, letting me reclaim 47.14 to 67.67 of GiBs back.

Elv13 · 12-04-2010, 12:30 AM

One may take into account the file system size (indexes, superblock backup, journal, structure, etc) while the other don't. Calculating RAM, CPU and HDD usage is tricky, there is no real number, it depend how to calculate it. It is why top, htop, ksysguard and gnome-system-monitor can agree with the CPU usage number. It is bettr for HDD, but still not perfect. Even the total disk size is usually not the same in cfdisk, gparted and fdisk

replica9000 · 12-05-2010, 07:43 PM

I found this article explaining more of what's going on here:
http://en.wikipedia.org/wiki/Binary_...umer_confusion

Quote:

Originally Posted by lazlow

Just a guess, but by default ext3 reserves 5% of the disk space for system use only.

Thank you for pointing this out. I didn't realize EXT3 does this. If you had not pointed this out, I could be missing out on over 93GiB of space on my 2TB HDD!