Can a non-redundant RAID5 cause any serious problems (compared to RAID0)?
- by leemes
I used to have a three-disc RAID5 (mdadm) in my computer for personal media storage (music, videos, photos, programs, games, ...). It had three discs with 750 GB each, resulting in an array capacity of 1.5 TB.
One day (one year ago), I needed one of those discs to install another operating system. I thought, I don't need the redundancy anymore since I backup the most important stuff (personal photos e.g.) on an external disc anyway. So I decided to remove one of the three discs without converting the RAID to RAID0 or even two separate discs, because I had no temporary storage (since one cannot simply convert the RAID5 to RAID0 AFAIK).
So now, for about one year, I have a non-redundant RAID5 with 2 of 3 discs running. Sometimes, one of the discs has a defective contact at the power cable or something similar causing the drive to stop working temporarily (I don't know exactly what it is). Since it still works when rebooting the computer and in most cases by calling some mdadm commands, it wasn't that problematic. Note that the data is not very critical, since I still have a backup of the most important stuff.
But in the last few weeks, one of the drives fails very frequently (every few hours), so it gets really annoying to manage this.
My questions are:
Is there any disadvantage (apart from the annoying management) of a non-redundant RAID5 (with one drive less than typical) over a RAID0? If I understand it correctly, both have no redundancy and the same capacity. On a temporary drive failure, I can restart the array in both cases, assuming that the drive itself still works after the failure.
Can it happen that the drive contents alter on a drive failure, making the array inconsistent? If so, can I tell mdadm to check the array for failures (without a file system level checking tool)?
Since the drive most probably only has a defective contact causing it to fail for a second only, can I tell mdadm to automatically restart the array, so I will not even notice the failure if no application wanted to access the file system during the failure?
