# Disk replacement¶

## Introduction¶

If you notice that one of your hard drive is failing or that our system notifies you by email that your server is experiencing a hard drive failure, you should take action as soon as possible to address the issue.

This document will guide you for the replacement of your failing hard disk.

## Backup¶

Before doing anything, it is really important to performs your backups. The sole purpose of a RAID (except RAID0) is to protect data against hard disk failures. Once a disk is failing, all your data depends on the health of the remaining disk.

It is improbable that two drives fails at the same time, but it is not impossible. By all means, implement an adequate backup strategy.

If you do not confirm that you have made your backup before asking for a disk replacement, you must state that you are aware of the risks and that you accept full responsibility.

## Find defective disk(s)¶

Whether you have found the failure by yourself or if our system notified you, it is good practice to check the health of all hard disks.

The reason is that if we have two failing disks in a RAID array, we will start by replacing the disk with the higher error count.

### Software RAID¶

If you have a Software RAID, use this guide to find the installed disks on your server.

Once you have found the device path of you disks, you can tests them using smartctl like so:

smartctl -a /dev/sdX


Note

Don’t forget to replace /dev/sdX for the actual device path of your disk.

### Hardware RAID¶

For Hardware RAID, use this guide and use the procedure related to your RAID controler to find out the devices path of your disks.

Once you have found the device path of you disks, you can tests them using smartctl like so:

smartctl -d megaraid,N -a /dev/sdX

N: The drive’s Device ID The RAID’s Device (/dev/sda = 1st RAID, /dev/sdb = 2nd RAID, etc.)

Note

Don’t forget to replace /dev/sdX for the actual device path of your disk.

## Requesting a disk replacement¶

To request a disk replacement, simply open a Support Ticket in the OVH Manager.

To accelerate the process, please provide the following informations:

1. A date and time at which we should perform the replacement (you must plan for a small down time, but replacements can be scheduled 24/24-7/7).
2. A confirmation that either you have made your backup or that you take full responsibility for any data loss
3. The serial number of the hard disk we must change (to find the hard disk’s serial number, please follow this guide) [1]
 [1] If for some reasons it is not possible to retreive the Serial Number of the failing hard disk, please specify it in the ticket and provide the Serial Numbers of all other disks.

## After the replacement¶

If you have Hardware RAID, the RAID will re-sync itself. Please note that the re-sync process can take some time and affect the read/write performances of your disks.

If you have Software RAID, then you will have to rebuild your RAID array. This guide explains how to do it.