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A SCSI hot swap hard drive will be used in server hardware as part of a disk array. They can also be used in Network Attached Storage (NAS) devices. The design of the hard disk allows for easy removal and replacement of any faulty unit. Although hard disk manufacturing and technology has come a very long way since the 1990′s, they are not infallible and do suffer from failure. Due to this fact, having a good RAID strategy and backup and disaster recovery plan is essential if you wish to keep your systems up and running 100% of the time.

1. Disk Size And Type
SCSI hard disks come in various different sizes (measured in gigabytes) and also from a varying number of manufacturers. The first point I would like to make is that it is better to replace SCSI hard disks with like for like models. Although some hard disks may appear to be the same size, they often get identified or reported as smaller or larger, depending on the manufacturer. So go with the same disk model if you can.

2. Trays And Caddys
Each SCSI hot swap drive sits inside a tray or caddy that allows for easy removal and insertion. The tray holds the disk securely, usually by the use of screws and slots into a bay in the server or rack. The tray usually has some form of levers of handles that are used to pull the disk in and out and also act as a locking mechanism.

3. Easy Does It
Although modern day hard disks are tough, they are not immune to the odd bump, bang or static shock. Make sure that you follow any health and safety guidelines when working with these drives. Also ensure that you carry out the drive replacement with care. We don’t want to damage the SCSI backplane now do we?

4. Slide Out Slide In
To remove the disk, un-clip the levers or handles that are keeping it secure and slide the disk out. You may now need to remove the casing of the tray or caddy and replace the hard disk. The interface on these trays can be delicate, so take care. Once the new or replacement disk is in place, slide it gently back into the server bay. Once you have made contact with the backplane, use the levers to secure the drive into place.

5. Let The RAID Magic Happen
All being well, the RAID array will detect the new disk, initialise it and begin to rebuild the data on to it. You may see a steady flashing light on the drive whilst this takes place, or you could observe what is happening from a software RAID or hardware console.

This is a very generic guide on how to replace a SCSI hot swap drive and you should always refer to your manufacturers guidelines and instructions. Server hardware changes quite often, so make sure you check out the server manufacturers website before attempting to perform these steps. Remember, safety first!

For more information on getting hold of replacement hard disks, head over to the http://www.scsihotswap.com website, where the author can help you find exactly what you need.