[CentOS] xfs not getting it right?

hw

hw at gc-24.de
Wed Sep 20 14:47:11 UTC 2017


Hi,

xfs is supposed to detect the layout of a md-RAID devices when creating the
file system, but it doesn´t seem to do that:


# cat /proc/mdstat
Personalities : [raid1]
md10 : active raid1 sde[1] sdd[0]
       499976512 blocks super 1.2 [2/2] [UU]
       bitmap: 0/4 pages [0KB], 65536KB chunk


# mkfs.xfs /dev/md10p2
meta-data=/dev/md10p2            isize=512    agcount=4, agsize=30199892 blks
          =                       sectsz=512   attr=2, projid32bit=1
          =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=120799568, imaxpct=25
          =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=58984, version=2
          =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0


# mkfs.xfs -f -d su=64m,sw=2 /dev/md10p2
meta-data=/dev/md10p2            isize=512    agcount=16, agsize=7553024 blks
          =                       sectsz=512   attr=2, projid32bit=1
          =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=120799568, imaxpct=25
          =                       sunit=16384  swidth=32768 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=58984, version=2
          =                       sectsz=512   sunit=8 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0


The 64MB chunk size was picked my mdadm automatically.  The device is made
from two disks, and xfs either doesn´t figure that out, or it decided to
ignore the layout of the underlying RAID.

Am I doing something wrong here, or is xfs in Centos somehow different?
Do, or must, we always specify the apporpriate values for su and sw or
did xfs ignore them because what it picked is better?




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