RAID (redundant array of independent disks, originally redundant array of inexpensive disk)is a storage system developed in the 80’s. It was during the time when drives are expensive. But it is a viable solution for online redundancy to protect against hardware failure. Anyway, a lesson in RAID is not what I wanted to tell in this “Experience” post. I wanted to quote from one of my experience on using RAID5 and how I think RAID5 is not a viable solution anymore in this modern era where drive technology has advanced by leaps and bound since the days of tapes.
Years ago in the 2000’s, I was building server for the company I was working with. Naturally, RAID5 comes to mind as it was the “right” thing to do for storage redundancy. Well, RAID5 is a viable option since it allow 1 drive to fail anytime and we had RAID5 running with 3 drives. Everything went well and fast forward to more than 5 years later, the drives begin to show signs of aging. In one miserable day, one of the drive in the RAID5 went dead. So we are chugging along with the 2 remaining drives. With the inexperience that I am, we did not have any hotspares not coldspares. I proceeded with ordering a new drive. As with the nature of fast moving technology, it is hard to find a replacement drive. The replacement quoted by vendor is crazy expensive. So I had a trip around looking for replacement in second hand shops. A few days passed by and then something terrible happened.
One of the remaining 2 drives failed as well. I am screwed. Screwed for not having proper disaster recovery placed. So I attempted to take drives to recovery centers. The said they can try to recover the data but no guarantee. On top of that, the price they quote, well..let’s say we can buy a few new servers with it. Naturally management did not approve of that recovery. But I got a serious lecture and they had to rebuild some important data from various locations filed in local PC.
Years later, I build another RAID5 system in my home. It did not end well too.
Out of some of my experience using RAID5, I can say I will stay away from RAID5 given the choice. Below are some of the reasons:
- hotspares are totally neccessary for RAID5. Else don’t use RAID5
- RAID5 are dependent on the controller. If the controller died, that whole array might not work. Depending on whether it’s hardware RAID or software RAID.
- RAID5 overrated. Better alternative would be RAID6 or RAID10.
For now, my choice of RAID would be RAID10. Cause anytime, I take one of the drives out, I can totally read all the files in it. I do not need to depend on other drives in order to recover few files in the array. For those who are still using RAID5, it is time to change to a better RAID system or at the very least have a good disaster recovery in place.