Create Raid6 with 1 missing member fails

2008-02-17 Thread Sevrin Robstad 

I tried to create a raid6 with one missing member, but it fails.
It works fine to create a raid6 with two missing members. Is it supposed 
to be like that ?


mdadm -C /dev/md0 -n5 -l6 -c256 /dev/sd[bcde]1 missing
raid5: failed to run raid set md0
mdadm: RUN_ARRAY failed: Input/output error
mdadm: stopped /dev/md0

mdadm --version
mdadm - v2.6.4 - 19th October 2007
uname -a
Linux compaq2.lan 2.6.23.15-137.fc8 #1 SMP Sun Feb 10 17:03:13 EST 2008 
x86_64 x86_64 x86_64 GNU/Linux


mdadm --examine /dev/sdb1
/dev/sdb1:
 Magic : a92b4efc
   Version : 00.90.00
  UUID : e4147673:e22e02ac:09e8c875:b3e364c1
 Creation Time : Sun Feb 17 14:31:55 2008
Raid Level : raid6
 Used Dev Size : 488295424 (465.67 GiB 500.01 GB)
Array Size : 1464886272 (1397.02 GiB 1500.04 GB)
  Raid Devices : 5
 Total Devices : 5
Preferred Minor : 0

   Update Time : Sun Feb 17 14:31:55 2008
 State : active
Active Devices : 4
Working Devices : 4
Failed Devices : 1
 Spare Devices : 0
  Checksum : d9c93170 - correct
Events : 0.1

Chunk Size : 256K

 Number   Major   Minor   RaidDevice State
this 0   8   170  active sync   /dev/sdb1

  0 0   8   170  active sync   /dev/sdb1
  1 1   8   331  active sync   /dev/sdc1
  2 2   8   492  active sync   /dev/sdd1
  3 3   8   653  active sync   /dev/sde1
  4 4   004  faulty

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Re: Create Raid6 with 1 missing member fails

2008-02-17 Thread Neil Brown 
On Sunday February 17, [EMAIL PROTECTED] wrote:
 I tried to create a raid6 with one missing member, but it fails.
 It works fine to create a raid6 with two missing members. Is it supposed 
 to be like that ?

No, it isn't supposed to be like that, but currently it is.

The easiest approach if to create it with 2 drives missing, and the
extra drive immediately.
This is essentially what mdadm will do when I fix it.

Alternately you can use --assume-clean to tell it that the array is
clean.  It is actually a lie, but it is a harmless lie. Whenever any
data is written to the array, that little part of the array will get
cleaned. (Note that this isn't true of raid5, only of raid6).

NeilBrown
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