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Which SAS cables shoul I get

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March 20, 2012 10:07:07 AM

Hi. I have 2 x Seagate cheetah 15k.6 drives on an Intel server attached through a SAS hot-swap expander, thus connected to the RAID controller by 2 sata 7-pin cables .

Since I'm buying a new custom built workstation, I was planning to transfer those disks on the new system. My question is, which cables should I get to properly connect the drives to the SAS/RAID controller? There are multiple type of cables available. Most of them are multilane and/or breakout cables which purpose I really don't understand.

I was thinking I should get this: http://www.cs-electronics.com/images/img061906/large/SA...
Then again, there's the same cable but in a dual host variant: http://www.cs-electronics.com/images/img061906/large/SA... - what would one gain with it?

Do I really need special cables or I can just connect the standard PSU sata power cable to the disks and a standard Sata cable from the disks to the controller?

More about : sas cables shoul

a c 302 G Storage
March 20, 2012 6:29:47 PM

With all due respect, get the ones with plugs that match the disk on one end and plugs that match the controller on the other. Depending on the connectors on the controller in the new custom built workstation, you may need a breakout cable or not.

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I'll try to shed more light on this, but I'm not really good at it. After reading here: http://en.wikipedia.org/wiki/Serial_attached_SCSI , I'm still not really good at it. I've never had my hands on the hardware. Invite me over to poke inside your box.

Dual-host variant is only useful if you are going to use dual hosts ;)  That means if you have redundant controllers, either in the same PC or one in this PC and one in the other PC. If the active controller fails, the drive can still be accessed through the other. Unless you install redundant controller cards in the new workstation, I think that this is not relevant to you.

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Drive-side, there is one connector with power and data. You can connect either a power-and-data cable, which will usually split to a power connector and a data connector for your drive, or a power cable and a separate data cable.

Then, let's say that you have four drives, with four power cables and four data cables. Some controllers will have four single-port sockets for the data cable. Others will have a multilane connector of one type or another (there are at least four), which is basically a space-saving method to minimize connectors on the controller card. If the controller has a multilane socket, you will need a breakout cable, since the disks have only one type of data connector.

By the way, the four types of multilane socket are internal, internal mini, external, and external mini.

My thought: If you are getting a system custom built by a competent builder, the builder should explain this to you thoroughly.

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Just to confuse matters more.

Here's a controller with two separate single-data-cable connectors: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Here's a controller that can control eight external single-data-cable far ends, with only two plugs on the controller. This requires multilane breakout cables: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Not to mention that each single-data-cable can go into a device called an "expander" and be connected to multiple physical drives. Of course, in this case the aggregate bandwidth of all the drives attached to one expander is limited to the speed of a single lane.

That's my brain-dump on the subject. I'd be happy to answer specific requests for clarification, but I'm not going to clean this up into a post with proper organization (I'm lazy today). The answer to your main question is "it depends what type of controller card / motherboard gets put into your new system."
March 20, 2012 8:47:03 PM

Gee. You really complicated my day. :) 

Atm. I own an Intel® RAID Controller SASWT4I : http://allthereviews.com/p/intel-raid-controller-saswt4... which have 4 sas/sata single-data ports. I'm not sure if the controller itself will be compatible with the consumer motherboard I'm planing to buy. In that case I'll probably get this SAS controller: http://www.tweaktown.com/reviews/4306/highpoint_rocketr... in which case I'll have to buy different connection cables.

I'm building the system myself. I consider myself to be quite competent but I don't have much experience with sas "wiring", although I've built the Intel workstation using the above mentioned hard drives and it was pretty straight forward.

If I'm getting this right, I've picked the right cable in my 1st post?
a c 302 G Storage
March 20, 2012 11:11:59 PM

OK. That controller is a 4-lane PCI Express card; it should be compatible with any current motherboard. Make sure that they have controllers for whichever OS you have - I don't know how old this is, but I've seen older hardware without 64-bit support.

What I will say about the cable in the first post is that it will work. It would not be my choice, since it's connecting SAS / SATA power to a Molex IDE power cable. Ideally, your power supply will have SAS/SATA power cables that you can plug into these drives directly, providing the "correct" support.

Oh, I give up. I just searched for SAS / SATA power cables, and they all show Y cables with a Molex connector. Yeah, those will work just fine.
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