RAID controller cards. (RAID1)

CyberGhost

When you have a 4 port RAID 1 controller card, how does mirroring work?

If you slap 4 drives on it, will 1 driver be mirrored by the other 3? or will they split in pairs? or will they act like RAID 0 just half the space?

Anti

depends how you set it up, and what you want really.

What card is it ?

CyberGhost

I want to have a very reliable backup solution, with 4 drives, RIAD 5 cards cost a bit too much so i thought I'd get a RAID 1 card with 4 ports(haven't decided which one yet), but I don't really know what possibilities are there with 4 drives and RAID 1?

quaidox

hi cyberghost, this might be the options available to you, but i am not 100% sure, as i deal only with raid 5 arrays in work....
"RAID 0+1: We stripe together drives 1, 2 into RAID 0 stripe set "A", and drives 3,4 into RAID 0 stripe set "B". We then mirror A and B using RAID 1. If one drive fails, say drive #2, then the entire stripe set "A" is lost, because RAID 0 has no redundancy; the RAID 0+1 array continues to chug along because the entire stripe set "B" is still functioning. However, at this point you are reduced to running what is in essence a straight RAID 0 array until drive #2 can be fixed. If in the meantime drive #3 goes down, you lose the entire array.

RAID 1+0: We mirror drives 1 and 2 to form RAID 1 mirror set "A"; 3 and 4 become "B" We then do a RAID 0 stripe across sets A and B. If drive #2 fails now, only mirror set "A" is affected; it still has drive #1 so it is fine, and the RAID 1+0 array continues functioning. If while drive #2 is being replaced drive #3 fails, the array is fine, because drive #3 is in a different mirror pair from #2. Only two failures in the same mirror set will cause the array to fail, so in theory, five drives can fail--as long as they are all in different sets--and the array would still be fine."
Hope this helps..................

CyberGhost

That's actually a pretty good method, I'll try it! Thanks Quaidox!