How mdadm can support > 2T

How mdadm can support > 2T

[俞先印]

Ilinux-raid want to create raid0 use mdadm 2.5.6, kernel 2.6.18-iop3 on the intel iop80331(32bit). use 5 disks, and every hard disk is 500G. But it can't beyond > 2T.  How can support >2T on the 32bit cpu ?  

command and log :
#mdadm -C /dev/md0 -l0 -n5 /dev/sd[c,d,e,f,g]
# mdadm --detail /dev/md0

root@iop:/# mdadm --detail /dev/md0
/dev/md0:
        Version : 00.90.03
  Creation Time : Thu Jan  1 00:29:29 1970
     Raid Level : raid0
     Array Size : 294448832 (280.81 GiB 301.52 GB)
   Raid Devices : 5
  Total Devices : 5
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Thu Jan  1 00:29:29 1970
          State : clean
 Active Devices : 5
Working Devices : 5
 Failed Devices : 0
  Spare Devices : 0

     Chunk Size : 64K

           UUID : ebdd57fe:8eb46fdf:884d06b0:5db18b9d
         Events : 0.1

    Number   Major   Minor   RaidDevice State
       0       8       32        0      active sync   /dev/sdc
       1       8       48        1      active sync   /dev/sdd
       2       8       64        2      active sync   /dev/sde
       3       8       80        3      active sync   /dev/sdf
       4       8       96        4      active sync   /dev/sdg

Re: How mdadm can support > 2T

[Chris Allen]

俞先印 wrote:
> Ilinux-raid want to create raid0 use mdadm 2.5.6, kernel 2.6.18-iop3 on the intel iop80331(32bit). use 5 disks, and every hard disk is 500G. But it can't beyond > 2T.  How can support >2T on the 32bit cpu ?  
>
> command and log :
> #mdadm -C /dev/md0 -l0 -n5 /dev/sd[c,d,e,f,g]
> # mdadm --detail /dev/md0
>
>   

I have many arrays which are 12TB or greater - so I don't think this is
your problem.
It looks like mdadm is only using 60GB from each disk.

What output do you get from these commands:

fdisk -l /dev/sdc

mdadm --examine /dev/sdc

?

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Re: How mdadm can support > 2T

[Neil Brown]

On Wednesday November 15, yu_xianyin@dahuatech.com wrote:

> Ilinux-raid want to create raid0 use mdadm 2.5.6, kernel 2.6.18-iop3
> on the intel iop80331(32bit). use 5 disks, and every hard disk is
> 500G. But it can't beyond > 2T.  How can support >2T on the 32bit
> cpu ?   

Make sure you have 
   CONFIG_LBD=y
in .config.  It works just fine.

NeilBrown