arghhh raid5 with 4x320GB drives and df returns 320GB for size of node!!!
 

hello everyone,
i am trying to set up raid5 with 4x 320GB drives at the moment.
while the process is still ongoing
i can check the raid configuration with mdadm -D /dev/md0.. that returns 'array size = 960GB'
this is normal and to be expected as n-1 = 4-1 = 3 drves x 320GB each = 960GB.

but if i df /dev/md0.. it returns 320GB..????

why does it do that?
nass

I don't trust df. Is it just df that's the problem ?

how else can i verify the result?
i thought only the Disk-Free utility returns the free disk space....

Hmmm ... I don't really know. I think unless there is RAID-specific program that does the same thing, 'df' may be the only way to check free disk space.

still i didn't leave it to chance.
i changed the drives type from the partition table with fdisk to 'linux' (code=83).
then reformatted all of them with mkreiserfs.
finally used the following /etc/raidtab file

raiddev /dev/md0
raid-level 5
nr-raid-disks 4
nr-spare-disks 0
persistent-superblock 1
parity-algorithm left-symmetric
chunk-size 128
device /dev/sdb1
raid-disk 0
device /dev/sdc1
raid-disk 1
device /dev/sdd1
raid-disk 2
device /dev/sde1
raid-disk 3

and did 'mkraid /dev/md0'...
this time around df returns the proper size (thats 4-1 drivers x 320GB = 960GB).
once done, i changed the partition table type back to 'fd' (linux raid) and
FORMATTED also /dev/md0 node, cause it wouldn't find a superblock on this node.
so mkreiserfs /dev/md0 too..
done with that too , i mounted, restarted and found that it was properly mounted...
and df always returns correct...

just a question. if i do:
i get this response...

is that normal? i mean only the partitions making up a raid array have a superblock? or the /dev/md0 node too?
nass

I think only partitions have a superblock.