tmpfs runs out of space on 8.2pre-release, zfs related?

Ronald Klop ronald-freebsd8 at
Sun Jan 2 15:26:45 UTC 2011

On Sun, 02 Jan 2011 09:41:04 +0100, miyamoto moesasji  
<miyamoto.31b at> wrote:

> miyamoto moesasji <miyamoto.31b <at>> writes:
>> In setting up tmpfs (so not tmpmfs) on a machine that is using
>> zfs(v15, zfs v4) on 8.2prerelease I run out of space on the tmpfs when
>> copying a file of ~4.6 GB file from the zfs-filesystem to the memory
>> disk. This machine has 8GB of memory backed by swap on the harddisk,
>> so I expected the file to copy to memory without problems.
> ....this is in fact worse than I first thought. After leaving the
> machine running overnight the tmpfs is reduced to a size of 4K, which
> shows that tmpfs is in fact
> completely unusable for me. See the output of df:
> ---
> hge at PulsarX4:~/ > df -hi /tmp
> Filesystem    Size    Used   Avail Capacity iused ifree %iused  Mounted  
> on
> tmpfs         4.0K    4.0K      0B   100%      18     0  100%   /tmp
> ---
> Relevant zfs-stats info:
> ---
> System Memory Statistics:
> 	Physical Memory:			8161.74M
> 	Kernel Memory:				4117.40M
> 	DATA:				99.29%	4088.07M
> 	TEXT:				0.71%	29.33M
> ARC Size:
> 	Current Size (arcsize):		63.58%	4370.60M
> 	Target Size (Adaptive, c):	100.00%	6874.44M
> 	Min Size (Hard Limit, c_min):	12.50%	859.31M
> 	Max Size (High Water, c_max):	~8:1	6874.44M
> ---
> I'm not sure what triggered this further reduction in size; but the
> above 4K size is probably important to show how dramatic this goes
> wrong.

Is it possible that some program is filling a file (on your tmpfs) which  
is deleted?
You will not see it with df or ls, but it still takes space on the fs,  
until the application closes the file.


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