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Raid-controller: grouping drives?

Last response: in Storage
September 15, 2010 8:36:01 AM

Hi everyone,

I'm surprised google turned up little or nothing on this type of question. :o 
I'm looking to build my own NAS and I'm aiming for 10 * 2 TiB, probably going for raid 6.

I'm just hitting my 'gathering information' stage, and I've been looking at some custom setups. However, I've noticed the number of ports on the RAID-controller is fewer than the number of physical drives. So, some kind of mechanism must be used to group drives. I've found a controller with 4 ports.

Can anyone please explain how this grouping works?

September 15, 2010 6:16:14 PM

What kind of drives are you raiding? SCSI or SATA? And can you link the controller you are looking at getting?
September 16, 2010 10:03:43 AM

hi endif,

I'm a little behind on this particular subject (mass storage). I'll be RAIDing SATA drives for sure.

Basically, a clever guy has made a similar project for a maximum of 20 drives. Apparently, I _think_ he has connected his drives directly to the motherboard using its onboard Raid controller. I don't want that (expandability is very low). you can take a look here:

Now, I'm sure a 1 to 1 relationship exists between the number of drives that he connects to a backplane (as you can see in the pictures he made of it). From there on it becomes fuzzy. Do the 20 (!) cables from the backplane travel to a 20 port raid controller?How do the cables travel from the backplane to the controller? Does a backplane group drives per 4, making only 5 cables travel from the backplane to the raid controller. I found a controller boosting 24 ports but there were by no means 20 physical ports.

So I'll either need a SATA-raid controller of a SAS-raid controller. I don't know which is best. So I'm basically stuck on how to connect the drives in an efficient way.

PS: He is using this chassis

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September 16, 2010 11:29:53 AM

I just need more information about this post.
:bounce:  Seo Servises
September 16, 2010 11:47:11 AM

Please, feel free to tell me what exactly you need to know. I'm just trying to find my way to the rabbit hole.

I will be stuffing a least 10 drives in a storage rack. Those drives will be SATA-drives (of course, hot swappable).

My questions are mainly about the connectivity options between the backplane where the drives "plug-in" and the (SATA or SAS) RAID-card. Consider the question in 2 directions: performance wise and cable management wise.

September 30, 2010 8:50:31 PM

To save on cables from the RAID card to the Drive back plane you will want a back plane with an SAS/SATA expander. This will way you will only need a x4 lane SAS/SATA connection between the RAID card and the Back plane. You can alternatively just buy a Drive box that has an expander and the RAID card will be in a separate server.