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Old 06-26-2007, 06:06 AM   #1
tataiermail
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same raid array on 2 O.S.


i have used two partitions from my two HDDs to
create a raid 1 array on suse.

the raid partitions are not part of std linux
file system, they are fat32 and hold data only.

i have RHEL also in my system, when i boot
in RHEL, it doesn't show any /dev/md0. (which is natural)
now when i use the same raid command with all
the same parameters, mdadm says:
/dev/hda5 seems to be a raid partition
/dev/sda6 seems to be a raid partition
do u want to create the array? y/n

i pressed no. as i was unsure what'll happen.
how can i use my raid array on both the OS?
should i go forward and create the array on RHEL too?
or should it detect automatically?
 
Old 06-26-2007, 07:40 AM   #2
macemoneta
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You don't want to create the array again, as you will lose data. You want to start the array (which should have happened automatically during boot when the partitions were detected). You can try to start the array manually with:

mdadm --assemble /dev/md0 /dev/hda5 /dev/sda6

If nothing else, it will tell you why the array is not being automatically started.
 
Old 06-26-2007, 10:48 AM   #3
tataiermail
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not automatically starting

thanx a lot,

i used ur advice and it worked. i issued the command and straight away the array was started. i saw the 2 md related daemons are on at run level 5. but when i reboot, the array is not started again.
dmesg says, searching for md devices, starting ...., ... started ok.

so, i don't know what's happening.
currently i have removed the fstab entry.
added mdadm --assembly and mount command in rc.local.
it's working.
but this should not be the way to go. right?
thanx again.
 
Old 06-26-2007, 10:53 AM   #4
macemoneta
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Did you remember to copy over the /etc/mdadm.conf file? When the system goes to autostart, it will use the scan option. Without the file, it won't know how to assemble the drives.

You can also just recreate it with:

echo 'DEVICE /dev/hda5 /dev/sda6' > /etc/mdadm.conf
mdadm --detail --scan >> /etc/mdadm.conf
 
Old 06-26-2007, 11:52 PM   #5
tataiermail
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thanks,
i'll try it today. yes, there is no /etc/mdadm.conf in my RHEL.
but in suse 10.2 also it's not there. then how suse is detecting it?
actually whatever documentation i found on soft raid on linux, is quite old. mostly on "raidtab". can u give me some links to good online resources abt. software raid?

thanks anyways,
 
Old 06-27-2007, 09:22 AM   #6
macemoneta
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You can grep your init scripts to see where mdadm is used. For example:

grep -r mdadm /etc/rc.d/*

On my (FC6)system, it's called from /etc/rc.d/rc.sysinit as:

/sbin/mdadm -A -s

There are a few good articles (in addition to the man page): 1, 2; you can probably find more.
 
  


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