Thread: mdadm : what's the minimum on reserved space

hi

trying create raid 1 on 2 2tb drives.

know there reserved space superblock, expect few kib... read 2mib somewhere.

drive 2000398934016 bytes , mdadm refuses create bigger 2000264560640 bytes. 128 mib of reserved space.

it's not of issue going 100mib of slack, still, explain limit ? it's not documented, or @ least not in man pages md or mdadm nor jumping @ me google fountain.

can explain what's happening ?

thanks,

from linux man mdadm:

option s not mode-specific

-z, --size=
amount (in kibibytes) of space use each drive in raid levels 1/4/5/6. must multiple of chunk size , must leave 128kb of space @ end of drive raid superblock. if not specified (as not) smallest drive (or partition) sets size, though if there variance among drives of greater 1%, warning issued.

of course large drives, you're going lose if it's gpt redundant partition tables. if it's boot drive, going lose 1mb allow bios_grub. leave 1mb unallocated before start of first partition. if ext3 or ext4 filesystem, takes away 128mib it's filesystem journaling. force less journaling, not recommended.

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