Bug 31542

Summary:	ext4 : "No space left on the device" persists even when I deleted more than 40GB of data
Product:	File System	Reporter:	Jaromír Cápík (tavvva)
Component:	ext4	Assignee:	fs_ext4 (fs_ext4)
Status:	CLOSED INVALID
Severity:	high	CC:	sandeen
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	2.6.37.2	Subsystem:
Regression:	No	Bisected commit-id:

Description Jaromír Cápík 2011-03-20 23:08:51 UTC

1.) I recently filled my data partition full and got an error dialog, that there's no space left on the device (Resume, Retry, Skip, Abort, ... don't remember exactly)
2.) I used different terminal in order to move some of the big files (more than 40GB in total) from the affected partition to a different harddrive. But df was still showing 0 bytes available.
3.) Even of that I tried to resume the copying mentioned in point 1.) and it worked ... the copying was finished successfuly. What a magic!
4.) The situation changed after the reboot. I cannot copy new files to the affected partition anymore even if there must be at least 30GB of space left.

This is what df returns:
-------------------------
Filesystem	1K-blocks	Used		Available	Use%	Mounted on
/dev/md6	1209519868	1175334268	0		100%	/mnt/data

The difference between total and used blocks gives more than 32GB and I'm sure that yesterday this space was filled with data.

I'm willing to do any non-destructive tests and collect any debug logs You need in order to find the root cause of this issue.

Comment 1 Jaromír Cápík 2011-03-20 23:27:10 UTC

NOTE : Unfortunately I was performing the mentioned scenario on Mandriva Linux with the latest Mandriva desktop kernel [2.6.33-7mnb2] (and I know You don't like non-Vanilla kernels even if they almost don't differ from Vanilla), but I truly believe, that this problem comes from the mainline and therefore it's present in the mainline too. 

The issue persists even when I try Vanilla 2.6.37.2 ...

Comment 2 Jaromír Cápík 2011-03-20 23:39:36 UTC

I just discovered, that I get "no space left" messages from user accounts only. The root account can fill the rest of the space without sign of problems ....

Comment 3 Jaromír Cápík 2011-03-20 23:43:56 UTC

Sorry ... this seems to be a feature I didn't know about ...

-> By default, 5% of the space on a filesystem is reserved for the root user. This is so that if the filesystem fills up, there's still a little space for root to come in and clean up the mess. You can change this percentage with the -m option of tune2fs; do not do this while the filesystem is mounted and read the manpage very carefully. This is a potentially dangerous operation.

Comment 4 Eric Sandeen 2011-03-20 23:46:18 UTC

That's right, you've run into the reserved-for-root space, which as you noted above, can be changed...

So CLOSED/NOTABUG I think?

-Eric

Comment 5 Jaromír Cápík 2011-03-21 00:05:16 UTC

Yep .... I've already resolved/closed.
But ... that points to the unintuitive df output, where the reserved part should be displayed. At the moment I don't know if that's easily possible, but I'll check that and create an enhancement ticket if so.