Re: Raid array is not automatically detected.

[Justin Piszcz <jpiszcz@lucidpixels.com>]

On Sat, 14 Jul 2007, Bill Davidsen wrote:

> Justin Piszcz wrote:
>> 
>> 
>> On Sat, 14 Jul 2007, Bill Davidsen wrote:
>> 
>>> Bryan Christ wrote:
>>>> My apologies if this is not the right place to ask this question. 
>>>> Hopefully it is.
>>>> 
>>>> I created a RAID5 array with:
>>>> 
>>>> mdadm --create /dev/md0 --level=5 --raid-devices=5 /dev/sda1 /dev/sdb1 
>>>> /dev/sdc1 /dev/sdd1 /dev/sde1
>>>> 
>>>> mdadm -D /dev/md0 verifies the devices has a persistent super-block, but 
>>>> upon reboot, /dev/md0 does not get automatically assembled (an hence is 
>>>> not a installable/bootable device).
>>>> 
>>>> I have created several raid1 arrays and one raid5 array this way and have 
>>>> never had this problem.  In all fairness, this is the first time I have 
>>>> used mdadm for the job.  Usually, I boot to something like SysRescueCD, 
>>>> used raidtools to create my array and then reboot with my Slackware 
>>>> install CD.
>>>> 
>>>> Anyone know why this might be happening? 
>>> 
>>> Old type arrays are assembled due to having the proper partition type, 
>>> 0xfd "Linux auto RAID" and are assembled by the kernel. All others are 
>>> assembled by mdadm running out of initrd or similar, and failures there 
>>> result from not having a proper config file in the initrd image.
>>> 
>>> IIRC raidtools does set the array partitions to the auto-assemble 
>>> partition type. Hope that points you in the right direction. Running
>>>   "fdisk -l"
>>> as root will let you see all the partitions, types, etc, for everything on 
>>> your system.
>>> 
>>> I may be wrong, I thought auto-assemble only worked with type 0 or 1.
>>> 
>>> -- 
>>> bill davidsen <davidsen@tmr.com>
>>> CTO TMR Associates, Inc
>>> Doing interesting things with small computers since 1979
>>> 
>>> -
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>>> 
>> 
>> I use auto-assemble (in conjunction with Debian's own startup scripts) and 
>> for my root RAID1 device,swap and /boot, it is automatically taken care of 
>> by the kernel.  For RAID5, it seems to work the same:
>> 
> Are those partitions type "Linux RAID" or is the assemble being run from the 
> init scripts? I suspect the latter.
>> [   58.919378] RAID5 conf printout:
>> [   58.919418]  --- rd:10 wd:10
>> [   58.919457]  disk 0, o:1, dev:sdc1
>> [   58.919498]  disk 1, o:1, dev:sdd1
>> [   58.919539]  disk 2, o:1, dev:sde1
>> [   58.919579]  disk 3, o:1, dev:sdf1
>> [   58.919619]  disk 4, o:1, dev:sdg1
>> [   58.919659]  disk 5, o:1, dev:sdh1
>> [   58.919719]  disk 6, o:1, dev:sdi1
>> [   58.919759]  disk 7, o:1, dev:sdj1
>> [   58.919799]  disk 8, o:1, dev:sdk1
>> [   58.919839]  disk 9, o:1, dev:sdl1
>> 
>> Justin.


The partitions are 0xfd: Auto-detect:

/dev/sdc1               1       18241   146520801   fd  Linux raid autodetect
/dev/sdd1               1       18241   146520801   fd  Linux raid autodetect
/dev/sde1               1       18241   146520801   fd  Linux raid autodetect
/dev/sdf1               1       18241   146520801   fd  Linux raid autodetect
/dev/sdg1               1       18241   146520801   fd  Linux raid autodetect
/dev/sdh1               1       18241   146520801   fd  Linux raid autodetect
/dev/sdi1               1       18241   146520801   fd  Linux raid autodetect
/dev/sdj1               1       18241   146520801   fd  Linux raid autodetect
/dev/sdk1               1       18241   146520801   fd  Linux raid autodetect
/dev/sdl1               1       18241   146520801   fd  Linux raid autodetect