bug in ufs?

Peter Jeremy peterjeremy at optushome.com.au
Tue Jul 7 08:17:12 UTC 2009

On 2009-Jul-05 21:56:23 +0400, "Marat N.Afanasyev" <amarat at ksu.ru> wrote:
>i have a strange problem with writing data to my ufs2+su filesystem.

Overall, I think you are pushing UFS and have hit one of its limits.

>1. i made a 1T gpt partition on my storage server, and formatted it:
>newfs -U -m 0 -o time -i 32768 /dev/da1p3a

'-m 0' is undesirable.  The default 8% free space is intended to hide
the sort of effect you've run into.  Unless you can find a slightly
bigger disk, I suggest you try building an 8K/1K filesystem by adding
'-b 8192 -f 1024' - this will be slightly slower than the default
16K/2K but will hopefully allow you to fit slightly more files in.

>2. i tried to move data from other servers to this filesystem, total 
>size of files is slightly less than 1T

Can you be more accurate than "slightly less than 1T" (ie how many
MiB) and what is the size distribution of the files?  The average size
is 48KiB but are they all roughly the same size or do they vary widely?
Are there many files <16KiB?

>3. i encountered a 'No space left on device' while i still have 11G of 
>free space and about 13 million free inodes on the filesystem:
>#df -ih
>Filesystem     Size    Used   Avail Capacity  iused    ifree %iused 
>Mounted on
>/dev/da1p3a    1.0T    1.0T     11G    99% 20397465 13363173   60% 

More significant figures are needed.  How about 'df -im' or 'df -ik'.
How close are you to fitting in all the files you want?

>all i want to know is whether this is a bug or a feature? and if such a 
>behavior is well-known, where can i read about it?

Have a read of /usr/share/doc/smm/05.fastfs/paper.ascii.gz - especially
the bits about "fragments".  Whilst this paper talks about the original
UFS and a 4K/1K configuration, the principles remain the same in UFS2.

Peter Jeremy
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