# mdadm software raid1 automatic failover

**URL:** <https://forums.suse.com/t/mdadm-software-raid1-automatic-failover/28498>\
**Category:** SLES Hardware\
**Created:** [August 4, 2016, 5:05pm UTC](https://forums.suse.com/t/mdadm-software-raid1-automatic-failover/28498 "2016-08-04T17:05:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dafrk](https://avatars.discourse-cdn.com/v4/letter/d/958977/32.png) [@dafrk](https://forums.suse.com/u/dafrk)\
**Post date:** [August 4, 2016, 5:05pm UTC](https://forums.suse.com/t/mdadm-software-raid1-automatic-failover/28498/1 "2016-08-04T17:05:39Z")

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Hello experts,

I have installed SLES 11 SP4 on power using the following scenario

we have multipathing and we have 2 LUNS  
one LUN is on data center A and one LUN is on data center B

on each LUN, i made two partitions on install via expert partitioner

/dev/mapper/LUN1\_part1 - 512 MB - ext3 - /boot  
/dev/mapper/LUN1\_part2 - 40,5 GB - no fs - not mounted

/dev/mapper/LUN2\_part1 - 512 MB - no fs - not mounted  
/dev/mapper/LUN2\_part2 - 40,5 GB - no fs - not mounted

then I made a software raid1 over mdadm on install time via expert partitioner  
/dev/md0 - on devices /dev/mapper/LUN1\_part2 and /dev/mapper/LUN2\_part2

then I created a volume group vg\_rootfs on /dev/md0

then I created the following logical volumes on vg\_rootfs  
lv\_rootfs - 5 GB - ext3 - /  
lv\_home - 5 GB - ext3 - /home  
lv\_opt - 5 GB - ext3 - /opt  
lv\_usr - 5 GB - ext3 - /usr  
lv\_var - 5 GB - ext3 - /var  
lv\_tmp - 5 GB - ext3 - /tmp  
lv\_var\_log - 3 GB - ext3 - /var/log  
lv\_swap - 2 GB - swap - swap

after installation I first wanted to test the failover by taking one LUN away from the system. So far i have NOT replicated the /boot sector via sfdisk to /dev/mapper/LUN2\_part1, but I think for this scenario this should not be necessary

when I take /dev/mapper/LUN1 away from the system (where the /boot sector ist), everything works fine. I can still write files to the file system and i can still do commands in my ssh session. Then I gave the system /dev/mapper/LUN1 back. Now I wanted to test to take away the other LUN and just reboot the system - this is where I fail.

when I take away /dev/mapper/LUN2, where the /boot sector is currently NOT replicated, ssh freezes and i cannot state any commands.

How to fix this?

Best regards

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<div class="post-metadata">

**Author:** ![Automatic\_Reply](https://avatars.discourse-cdn.com/v4/letter/a/ecb155/32.png) [@Automatic\_Reply](https://forums.suse.com/u/Automatic_Reply)\
**Post date:** [August 10, 2016, 7:30am UTC](https://forums.suse.com/t/mdadm-software-raid1-automatic-failover/28498/2 "2016-08-10T07:30:32Z")

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dafrk,

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