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战斗力 鹅
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注册时间 2016-11-22
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发表于 2020-10-19 00:21
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本帖最后由 伊莉伊莉雅 于 2020-10-19 00:50 编辑
For XFS, the empty filesystem "Size Used" as shown by df -h seems to depend a lot on which metadata features you enable at mkfs.xfs time.
Testing with an empty 12TB file:
# truncate -s 12TB xfstest.img
Default settings (on my current ArchLinux system):
# mkfs.xfs xfstest.img
meta-data=xfstest.img isize=512 agcount=11, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=0
= reflink=0
data = bsize=4096 blocks=2929687500, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o loop xfstest.img loop/
# df -h loop/
Filesystem Size Used Avail Use% Mounted on
/dev/loop0 11T 12G 11T 1% /dev/shm/loop
# umount loop/
Using reflink=1:
# mkfs.xfs -m reflink=1 -f xfstest.img
meta-data=xfstest.img isize=512 agcount=11, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=0
= reflink=1
data = bsize=4096 blocks=2929687500, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o loop xfstest.img loop/
# df -h loop/
Filesystem Size Used Avail Use% Mounted on
/dev/loop0 11T 78G 11T 1% /dev/shm/loop
Using crc=0, reflink=0: (for some reason, that also turns finobt=0, sparse=0)
# mkfs.xfs -m reflink=0 -m crc=0 -f xfstest.img
meta-data=xfstest.img isize=256 agcount=11, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0 finobt=0, sparse=0, rmapbt=0
= reflink=0
data = bsize=4096 blocks=2929687500, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o loop xfstest.img loop/
# df -h loop/
Filesystem Size Used Avail Use% Mounted on
/dev/loop0 11T 33M 11T 1% /dev/shm/loop
In short:
# df -h loop/
Filesystem Size Used Avail Use% Mounted on
/dev/loop0 11T 78G 11T 1% /dev/shm/loop (reflink=1, crc=1)
/dev/loop0 11T 12G 11T 1% /dev/shm/loop (reflink=0, crc=1)
/dev/loop0 11T 33M 11T 1% /dev/shm/loop (reflink=0, crc=0)
So "Used" space on a fresh 12TB filesystem is 78G, 12G or as low as 33M depending on which metadata features you enable at mkfs time. 查了下应该是正常情况,估计默认开了reflink |
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