Troubleshooting RAID NAS

An integral part of any IT professional’s job is the ability to investigate and solve problems with RAID and servers. This is known as “troubleshooting” and before we go on to discuss this, let’s clear up and common misunderstanding, the difference between RAID and Servers. Not all servers run RAID, but all RAID are types of servers. RAID is simply a way of enabling computers to use multiple hard drives in a clever way, improving file access speeds and also providing some form of data protection against file loss. RAID comes in a variety of flavours but we can make a general differentiation between smaller home systems and larger business ones.

RAID 5 writes data to all hard disksThe proliferation of NAS hard drives has bought RAID into the home user environment. Most NAS hard drives are multiple hard disk systems containing either 2, 4 or 6 hard drives. Usually these system don’t need to be any larger than this as the average amount of storage a home user needs is will be covered. Home systems run mostly RAID 1 or RAID 5. RAID 1 is called ‘mirroring’ and usually consists of 2 hard disks that are an exact mirror of each other. The idea here is that should one of the hard disks fail, the data is safely preserved on the other. It’s a simple idea that works well. Some 2 disk RAID systems run a RAID 0 structure and RAID 0 is a bad idea because the data stored on a RAID system is divided up between the two drives, with no complete files being stored on either hard drive. Instead when file access from the RAID 0 is requested, the files are constructed from both hard drives and presented as a full file. This only advantage this serves is that the data transfer speeds are incredibly fast. A huge downside is that the is no safety net should either of the hard drives break. Indeed a fail to either drive will result in the total loss of all data, because files are split divided across the two hard drives. Because of this short coming, RAID 0 is hardly used anymore, and understandable so.

The larger NAS hard drives consisting of either 4 or 6 disks run in either RAID 5 or RAID 6. Both these types of RAID provide decent file transfer speeds and offer data protection too. RAID 5 will allow for one of the disks to completely fail and for RAID 6, this becomes 2 hard disks. So, a 6 disk RAID 6 will still work fine if 2 of its drives break and there will be no loss of data.

Troubleshooting RAID and NAS is a skill in itself – many IT professionals are not up to the task as repairing RAIDs and NAS hard drives is something they very rarely have to do. Additionally, there is the added complexity that the user’s data is involved, and any wrong move often results in the user’s data being lost. In both home and work environments, this is bad news as it’s either going to result in the loss of things like family photos and other cherished memories, or it’s going to result in the loss of (sometimes crucial) business data.

Our advice is to not involve inexperienced (although well meaning) computer troubleshooters to attempt to recover the data from any type of RAID systems. This is especially important on the larger RAID 5 and RAID 6 systems, as the more disks that are involved, the more difficult it is to identify the problems and troubleshoot the repair. Instead engage a company that know about RAID and hard drives, such as Emergency RAID Data Recovery or Datlabs Data Recovery, whose RAID recovery pages can be found here and

Regional Locations for RAID and NAS Recovery

Whilst most RAID specialists have only one point of presence in the UK, Data Clinic have regional offices in London, Manchester, Liverpool, Birmingham, Leeds, Glasgow, Northampton, Sheffield and Southampton. They also have a countrywide emergency RAID service that can be called out to any business location. Their main RAID recovery page is here and contains lots of relevant information.