The information provided in the FAQ and on several web sites is not really
useful regarding RAID1.
According to the FAQ (entry 35):
The correct options to format a RAID1 (2 disks) with 64k chunk size is:
mkfs.xfs -d su=64k -d sw=1 /dev/mapper/data
But it also states that it would be automatically detected and used correctly,
yet
mkfs.xfs /dev/mapper/data
yields a different result:
[root@atvie01s ~]# mkfs.xfs -f /dev/mapper/data
meta-data=/dev/mapper/data isize=256 agcount=4,
agsize=244173876 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=0 finobt=0
data = bsize=4096 blocks=976695504, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal log bsize=4096 blocks=476902, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
Formel 1:
[root@atvie01s ~]# mkfs.xfs -f -d su=64k -d sw=1 /dev/mapper/data
meta-data=/dev/mapper/data isize=256 agcount=32,
agsize=30521728 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=0 finobt=0
data = bsize=4096 blocks=976695296, imaxpct=5
= sunit=16 swidth=16 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal log bsize=4096 blocks=476902, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
Another inconsistency is that RAID1 doesn't use striping, so the chunk size
should be irrelevant in the first place.
So what is ultimately the correct way to format a RAID1?
Cheers,
K. C.
--
regards Helmut K. C. Tessarek
lookup http://sks.pkqs.net for KeyID 0xC11F128D
/*
Thou shalt not follow the NULL pointer for chaos and madness
await thee at its end.
*/
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