You pray that you will never need them but if worst comes to the worst how do you choose someone to trust from the myriad RAID recovery services represented online?
The first point to understand is that even within the already tightly focused field of hard drive data recovery the work of this represents another level of specialisation. Most recovery companies that are serious about RAID will have at least one in-house specialist. Those that do not will almost certainly forward your job to a service that does (with, of course, a mark-up for their trouble).
Your first task then is to know enough to filter the experts from those that won’t admit that they are not. As with any area of expertise, you don’t need to know much to spot the charlatan, just a little more than they do. Before you approach any company make sure that you know:
- What type of RAID it is that you have.
- The bare bones facts about how it works.
This will satisfy you as to which of the services are genuine when you discuss your case with them. To facilitate this there is a full article here, but below is a quick summary telling you enough to be able to chat knowledgeably with an expert (or indeed to spot someone who is solely interested in parting you from your money).
Quick Bluffer’s Guide for Use When Talking about RAID Recovery:
It is almost certain that your particular RAID will be one of the following three configurations. 95% will fall into one of these three configurations.
RAID 0:
Usually composed of 2 hard drives within a single external hard drive enclosure, but can include any number of physical hard drives. The capacity of the storage volume is usually the key to identifying it. If you have 2 hard drives each of 500GB capacity then the storage space available to the users will be 1TB. This sounds obvious but as you will see with the other types it is the only one which offers the full physical capacity of the hard drives to the user. It can do this because there is no protection for the data against hard drive failure (again in stark contrast with the other two configurations). RAID 0 is only ever selected in order to get faster access to the data stored in it. It greatly increases the risk of data loss though hardware failure because if any one of the physical drives fails then access to all user data is lost. This is because every individual file is stored partly on the first physical drive, partly on the next and so on through the drives which comprise the array. As you can imagine these are the most common type of failure seen by RAID recovery services.
The most common implementation is probably the external hard drive which houses 2 or more physical hard drives. The first time that the external is connected to a computer the user will typically be asked if they want to configure the external as striped or mirrored.
RAID 1 (also referred to as a mirror)
Usually composed of two physical hard drives, again most commonly seen within a single external hard drive enclosure. Each file is written twice, once to each of the physical hard drives. This means that the available space to the user is only half that of RAID 0. In the case of our two 500GB hard drives the total storage space available would be 500GB. Of course if one of the drives fails then the data should still be safe on the other. For this reason of course many fewer RAID 1 storage volumes will ever need recovery.
RAID 5
This will have a minimum of 3 physical hard drives. As with RAID 0, your individual files are stored in part on each of the physical hard drives in the array. One of the more common examples is the Buffalo Terastation external storage devices. There are many variants but one of the most widely used is the 4 drive RAID 5. This usually has four 1TB hard drives connected together to form a single RAID 5 storage volume. It offers a compromise between the characteristics of level 0 and level 1. On the one hand the speed of access to the data is faster than it would be if the data were stored on a single drive, but more importantly it offers increased protection for the data against hardware failure. Any single one of the physical hard drives in the array can fail and yet you will still have access to all of your data (for advice on how to proceed if this is the current stage of failure, then this post will be of help. This is possible because in addition to storing your data, the controller (a built-in part of the RAID device which houses the physical hard drives) also stores additional information derived from the data (called “parity”) which allows the data to be re-calculated if one of the drives is lost. This means that a little of the storage space is sacrificed. For any RAID 5, one hard drive’s worth of space is required for the parity and thus will not be available to the user. In the case of our four 1TB hard drives, the available space for the user’s data would be 3TB.
Should a second hard drive fail before the first one has been replaced and the RAID re-built then all user data access will be lost and it is time to contact recovery services.
A range of Lacie devices.
Knowledge is Power When Discussing Your RAID Recovery Problem
It is really worthwhile knowing which of these you have; a knowledgeable client is much less vulnerable to those “recovery software” data recovery companies posing as RAID experts. These guys don’t understand how to re-build a failed RAID from fundamental principles but will simply plug your drives back into your original controller and run recovery software on it. Once in a while this will return enough data to get them paid, but time after time this scatters the data beyond the ability of the genuine experts to recover it. Ask anyone in the professional RAID recovery services sector and they will confirm the regular frustration experienced when a re-build ultimately fails because someone inexperienced has done precisely this.
If in doubt the Tierra team are always happy to discuss your recovery services needs and options, for more information on our specialist recovery operations have a look at our RAID page.
