mdadm to create RAID1 on existing CENTOS

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mdadm to create RAID1 on existing CENTOS

Post by jojoy2k » 2016/10/24 07:56:49

I am using CENTOS 5.8.

I had been using CENTOS system about a year.
Recently, I felt that my OS and HDD requires a redundant mirror, so I want to try out mdadm utility to create a RAID1 mirror instead.
This is to duplicate my current CENTOS + HDD to create exact mirror.
I bought an identical hard disk (1TBB and same brand/model by WD).

1) I would like to create a raid1 on this existing CENTOS and duplicate it without any data loss. Is that ok?
2) Is mdadm suppose to use before OS installation? (unsure but don't think so).
3) Is there any correct steps to achieve this? by using mdadm.

Current OS is in /dev/sda, new added harddisk is /dev/sdb

The main reason I ask here is I worry that I format or do it wrongly and mdadm will remove my existing CENTOS OS instead.

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Re: mdadm to create RAID1 on existing CENTOS

Post by TrevorH » 2016/10/24 10:32:10

Given that CentOS 5 now has less than 6 months of life left and you are already a long way backlevel (current is 5.11, 5.8 dates back to 2012), I would recommend that you take a longer term view and plan to reinstall using a more recent version. CentOS 6 has about 4 years left but is about to enter production phase 3 where only critical security bugs will be fixed. CentOS 7 has until 2024 before it expires and is the most recent version.

As of March 2017 there will be no more security updates for CentOS 5.
CentOS 6 died in November 2020 - migrate to a new version!
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CentOS 5 is dead, do not use it.
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