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From: Dave Chinner <>
To: Alexander Tsvetkov <>
Subject: Re: maxpct option for small xfs filesystems
Date: Tue, 27 Jan 2015 09:37:15 +1100	[thread overview]
Message-ID: <20150126223715.GA7621@dastard> (raw)
In-Reply-To: <>

On Mon, Jan 26, 2015 at 07:14:43PM +0300, Alexander Tsvetkov wrote:
> Hello,
> I'm trying to understand the expected behaviour of "maxpct" option
> in case of small xfs filesystem
> comparing the maximum percentage defined for this option with the
> percentage of actually allocated
> inodes in filesystem, but the result of prepared test case doesn't
> correspond to the expectations:
> [root@fedora ~]#mkfs.xfs -f -d size=16m -i maxpct=1 /dev/sdb2

On 3.19-rc5, immediately after mount:

# df -i /mnt/scratch
Filesystem     Inodes IUsed IFree IUse% Mounted on
/dev/ram1         640     3   637    1% /mnt/scratch

Which indicates that imaxpct=1 is being calculated correctly, before
we even look at whether it is being enforced correctly or not.

So, what kernel version?

> [root@fedora ~]# for i in {0..100000}; do str=$(mktemp
> --tmpdir=/mnt/scratch tmp.XXXXXXXXXX); echo $str; done

Which is a complex (and very slow!) way of doing:

# for i in {0..100000}; do echo > /mnt/scratch/$i ; done 2> /dev/null

> filesystem is full with created files:
> [root@fedora ~]# df -Th | grep scratch
> /dev/sdb2      xfs        13M   13M  148K  99% /mnt/scratch

# df -Th /mnt/scratch
Filesystem     Type  Size  Used Avail Use% Mounted on
/dev/ram1      xfs    13M  1.1M   12M   9% /mnt/scratch
# df -i /mnt/scratch
Filesystem     Inodes IUsed IFree IUse% Mounted on
/dev/ram1         640   640     0  100% /mnt/scratch

> and from the number of actually created inodes:
> [root@fedora ~]# xfs_db -c "blockget -n" -c "ncheck" /dev/sdb2 | wc -l
> 40512

That's a directory structure entry count, equivalent to 'find
/mnt/scratch | wc -l', not an allocated inode count which is what
'df -i' reports. Even so, on 3.19-rc5:

# xfs_db -c "blockget -n" -c "ncheck" /dev/ram1 | wc -l

which matches what 'df -i' tells us about allocated inodes and hence
imaxpct is working as expected.


Dave Chinner

xfs mailing list

  reply	other threads:[~2015-01-26 22:37 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-26 16:14 maxpct option for small xfs filesystems Alexander Tsvetkov
2015-01-26 22:37 ` Dave Chinner [this message]
2015-01-27 16:23   ` Alexander Tsvetkov
2015-01-27 16:31     ` Eric Sandeen
2015-01-27 19:15       ` Eric Sandeen
2015-01-28 10:41       ` Alexander Tsvetkov
2015-01-28 15:44         ` Eric Sandeen
2015-01-28 18:05         ` Eric Sandeen

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