Re: mdadm create size problem

[Herta Van den Eynde <herta.vandeneynde@cc.kuleuven.be>]

OK, there's definitely something wrong here.  I ran a
# mdadm --zero-superblock --force /dev/sdX
followed by
# dd if=/dev/zero of=/dev/sdX bs=64k
where X=[g-in-p], and when I try to create a RAID 1 using two of these
devices, it still sets the size to 139904K.  When I create a RAID 0
using the same devices, mdadm does set the size correctly.

# mdadm --create --verbose /dev/md6 --level=1 --raid-devices=2 /dev/sdh
/dev/sdo
mdadm: size set to 139904K
mdadm: array /dev/md6 started.

# mdadm --create --verbose /dev/md6 --level=0 --raid-devices=2 /dev/sdh
/dev/sdo
mdadm: chunk size defaults to 64K
mdadm: array /dev/md6 started.
# mke2fs -j -v  /dev/md6
(...)
# mount /dev/md6 /mnt; df /mnt
Filesystem           1k-blocks      Used Available Use% Mounted on
/dev/md6             141124600     32828 133923052   1% /mnt

Is this a bug, or am I overlooking something?

Herta


Herta Van den Eynde wrote:
> Red Hat AS 2.1 mdadm 1.11
> I have two devices that used to be part of a now corrupt RAID10 
> configuration.  When I try to reuse them to create a RAID1, it only uses 
> about 1 third of the diskspace available.
> # fdisk -l /dev/sdg
> 
> Disk /dev/sdg: 255 heads, 63 sectors, 8924 cylinders
> Units = cylinders of 16065 * 512 bytes
> 
>    Device Boot    Start       End    Blocks   Id  System
> /dev/sdg1             1      8924  71681998+  fd  Linux raid autodetect
> 
> # fdisk -l /dev/sdn
> 
> Disk /dev/sdn: 255 heads, 63 sectors, 8924 cylinders
> Units = cylinders of 16065 * 512 bytes
> 
>    Device Boot    Start       End    Blocks   Id  System
> /dev/sdn1             1      8924  71681998+  fd  Linux raid autodetect
> 
> # mdadm --create --verbose /dev/md5 --level=1 --raid-devices=2 /dev/sdg 
> /dev/sdn
> mdadm: /dev/sdg appears to contain an ext2fs file system
>     size=419520K  mtime=Mon May  2 17:04:04 2005
> mdadm: /dev/sdn appears to contain an ext2fs file system
>     size=419520K  mtime=Mon May  2 17:04:04 2005
> mdadm: size set to 139904K
> Continue creating array? n
> 
> If I try to add the --size option, even a size that is 139904K or less, 
> it tells me the size is invalid:
> 
> # mdadm --create --verbose /dev/md5 --level=1 --raid-devices=2 /dev/sdg 
> /dev/sdn --size=139904K
> mdadm: invalid size: 139904K
> 
> I did reboot the system after fdisk'ing the devices.
> 
> Do I need to low-level format these devices to be able to reuse them?
> 
> Kind regards,
> 
> Herta
> 

-- 
Herta Van den Eynde              -=- Toledo system management
K.U. Leuven - Ludit              -=- phone: +32 (0)16 322 166
                                  -=- 50°51'27" N 004°40'39" E

"I wish I were two little cats.  Then I could play together."

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