EMVS software RAID Recovery

EVMS stand for Enterprise Volume Management System. However some linux geek like us have put the use to our home server. Which is not that well protected (No UPS, not Hardware Raid card). And that is where this guide came from.

Most of the time for the home server when our EVMS fail, it don't really have a hardware issue that need us the replace the HDD.

The problem might happen right after a lightning storm and caused a power trip (or Twice) then you will end up in the web searching to find the solutions.

Always it will shown as superblock mis-match (This is almost identical to a real HDD Fail issue in actual environment)

This guide will guide you through some simple step on recovery from a software raid + evms.

Preparation
1) You will need a Crashed EVMS volume.

2) A recent Gentoo Boot/live CD/DVD

3) A new HDD (If there is really a faulty HDD)

Starting of Recovery
Please boot with your gentoo live CD.

During boot time please user the kernel parameter that you need in additional of "doevms"

Now standby for your revocery system to startup.

Starting EVMS
During the start there will be part of the log showing that there is certain PV recornise not as PV (If you are using LVM with EVMS), this is a good sign. This meant that the EVMS is running fine.

However, You cannot run the recovery now as becuase your raid device node is not created yet.

Running this will create the missing raid node.

You will see some error telling you which md is degreaded and etc. Just click "Cancle" If you don't know which Raid fail and which drive have a mis-match super block checked it here.

You can then Quit this tools with

recovery using mdadm
If you fail md is md1 and support your drive group are /dev/sda5 /dev/sdb5 /dev/sdc5 /dev/sdd5

Assume that your md1 node is located at /dev/md1

As for my case all my device node have become /dev/evms/.nodes/sda5 /dev/evms/.nodes/sdb5 /dev/evms/.nodes/sdc5 /dev/evms/.nodes/sdd5

A Faulty Drive
You will have to 1st replace the faulty drive then try the this command Similar to the above case.

You will prompt for question asking if you want to continue adding this drive to the raid. Key in if you are sure what you are doing.

The next step we will do is to add the backup drive back in to the system. Your new sdb5

If Everything run well, you raid should start recovery now.

Recovery Raid State
You can use

To check on the status. Please allow that step to finished.

You can now reboot the system and wait for the 2nd recovery (Don't ask me why but that will happen)