It seems to be appealing to choose a Hardware RAID solution over a software RAID solution. However, there are things to know before going ahead with a hardware RAID. Some RAID card controllers include a battery backup unit (BBU) to avoid data corruption in case of a power failure. What would happen if this rechargeable battery would not work anymore? I think there is a risk of losing data. When the data blocks are striped the hardware RAID controller uses a proprietary system to record data on the drives. This system is not open source. Furthermore, someone has to check from the terminal to see if the battery state is ok. When you perform the maintenance of your own server, I guess you would do it. On the other hand, would a technician really check every battery if there are thousands of them in the data center? I don’t think so. Anyways, I have never found information about the maintenance of BBUs on a web hosting company website. No web hosting company communicates about the monitoring, maintenance or the replacement procedure of their hardware RAID controller. That’s why I don’t trust hardware RAID. I think about the situation, where the battery would be dead, a power failure would occur during a critical write operation on the RAID array, the data in the cache would be lost and the whole RAID array would be corrupt.
Using a hardware RAID controller is more complicated than managing a software RAID. In the bios, the hardware RAID controller requires additional settings. If the raid cache is misconfigured, it can result in a data loss.
If the hardware RAID controller fails, the drive must be installed on an identical RAID controller card with the same firmware version and the same settings. It means that your dedicated web hosting company should keep a copy of your actual RAID controller card with the same firmware version and settings to recover a RAID 5 or a RAID 10.
We know the story of 2 webmasters who lost all their data on hardware RAID. The first one had no RAID controller with the same firmware version as its faulty RAID controller. The second one lost everything because of the cache memory. There was a power failure and the RAID controller was writing on the hard drive. The data was corrupt when the power came back and It was a striped RAID 5.
So, in this case, when you send it to a recovery company, there will have difficulties to recover the data because, on the disk, the data on the blocks aren’t in clear. It goes through the stripped method of the RAID hardware controller which is patented by the hardware controller manufacturer. Take a look at this page from Adaptec and you will see that replacing a faulty RAID controller is not easy.
That’s why many of the web hosting companies only offer hardware RAID 1. That’s because the RAID blocks on a RAID 1 are not stripped and it is easier to recover the data thanks to the second drive which is just identical to the first drive. Consequently, a technician can plug the Drive to whatever regular disk controller and it will work!
That’s the reason why choosing a hardware RAID 1 is the safest solution when ordering a dedicated server plan at a web hosting company. If you would look for a redundant solution, it would be better to opt for a cloud hosting solution.
My testimonial of a faulty HD using software RAID at Leaseweb in Amsterdam
At first sight, RAID in Linux may look complicated. However, it is efficient and reliable. On my Linux server, I have set up a RAID 5 on 3 drives with automated SMART (smartctl) notifications. One day, I started to receive notifications from SMARTctl, the S.M.A.R.T monitoring service that I installed on Centos. It reported that one HDD drive was dying to the support team. I opened a ticket and a technician replaced the faulty HDD drive. Thanks to
The software RAID does work. On the other hand, I don’t trust hardware RAID since I have heard of two people who lost all their data on hardware RAID because of a power failure.
Update
There is something I forgot. The software raid in linux as regenerating scheduled job that happens every week. Write a comment if you are aware of it.