buildin a RAID5 md vith 6 drives

buildin a RAID5 md vith 6 drives

[J.A. Magallon]

Hi all...

I tried to build a RAID5 array with 6 drivres, just with:


mdadm --create --verbose --run \
        /dev/md0 --level=5 --chunk=256 \
        --raid-devices=6 \
        /dev/sda1 /dev/sdb1 /dev/sdc1 \
        /dev/sdd1 /dev/sde1 /dev/sdf1

And the raid looks in an strange state:

nada:~# mdadm -D /dev/md0
/dev/md0:
        Version : 00.90.01
  Creation Time : Fri Sep  3 02:17:28 2004
     Raid Level : raid5
     Array Size : 1225557760 (1168.78 GiB 1254.97 GB)
    Device Size : 245111552 (233.76 GiB 250.99 GB)
   Raid Devices : 6
  Total Devices : 6
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Fri Sep  3 02:42:32 2004
          State : clean, degraded, recovering
 Active Devices : 5
Working Devices : 6
 Failed Devices : 0
  Spare Devices : 1

         Layout : left-symmetric
     Chunk Size : 256K

 Rebuild Status : 8% complete

           UUID : fd6fcad0:21da140b:072a82b1:11b3db21
         Events : 0.30

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1
       2       8       33        2      active sync   /dev/sdc1
       3       8       49        3      active sync   /dev/sdd1
       4       8       65        4      active sync   /dev/sde1
       5       0        0        -      removed

       6       8       81        5      spare rebuilding   /dev/sdf1

Why does it think a drive has been removed, and the last drive is a spare ?
Isn't raid5 symmetric over all drives ?

TIA

--
J.A. Magallon <jamagallon()able!es>     \               Software is like sex:
werewolf!able!es                         \         It's better when it's free
Mandrakelinux release 10.1 (Beta 1) for i586
Linux 2.6.8.1-mm4 (gcc 3.4.1 (Mandrakelinux (Alpha 3.4.1-3mdk)) #8

Re: buildin a RAID5 md vith 6 drives

[Neil Brown]

On Friday September 3, jamagallon@able.es wrote:
> Hi all...
> 
> I tried to build a RAID5 array with 6 drivres, just with:
...
> Why does it think a drive has been removed, and the last drive is a spare ?
> Isn't raid5 symmetric over all drives ?

Read 
  man mdadm
the section on "CREATE MODE", the last paragraph before the "General
Management options" are listed.  Be sure that you have mdadm 1.4.0 or
later.

NeilBrown


[ the paragraph reads:
       When creating a RAID5 array, mdadm will automatically create a degraded
       array  with  an  extra spare drive.  This is because building the spare
       into a degraded array is in general faster than resyncing the parity on
       a  non-degraded, but not clean, array.  This feature can be over-ridden
       with the --force option.
if you remove the "-I" that really shoudn't be there... :-(
]




> 
> TIA
> 
> --
> J.A. Magallon <jamagallon()able!es>     \               Software is like sex:
> werewolf!able!es                         \         It's better when it's free
> Mandrakelinux release 10.1 (Beta 1) for i586
> Linux 2.6.8.1-mm4 (gcc 3.4.1 (Mandrakelinux (Alpha 3.4.1-3mdk)) #8
> 
> 
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