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How do external scsi towers work?

T

Titan

Golden Member
Hi all,

I'm planning for the future of a comp I want to build next year. I want to do HDTV capture, and for that I will need a fast RAID. I am looking at using U320 scsi, as the drives seem kinda cheap (for older 9 and 18gb drives) I am toying with the idea of getting many cheap small drives instead of a couple big drives, that seems more cost-effective. Trouble is, i don't want to cram that many drives into my main case, and am wondering how I could use the external connector on a scsi card.

I have googled and googled and can't seem to find much info on external RAID cases, or how they work. Any links and info are appreciated. Basically, I want to know if i can use a seperate case, link all the drives with one external cable, and run the raid into a controller card in my PC. Naturally, I would need a seperate power supply in the case to power the drives, but would the controller need to be in the case, or could I just use the cable?

Thanks in advance!
 
First, for U320 SCSI to do any good, you need a 64 bit PCI slot, these usually only come on server motherboards. I think the Tyan Thunder K8 has them (at $436), and it takes registered memory and Opteron CPU's (1 or 2).

Now once that is done, the rest is easy, get a good SCSI raid card (LSI U320-2 or something like that), then an external SCSI cable, and then the enclosure. What I did, was take an old 485 tower, remove the motherboard, and put 5 18 gig SCSI drives in it. I also had to mod the case to add a 120x38 92cfm fan to keep the drives cool. Then a SCSI cable inside (standard) that goes to an external connector (picked up at a local store) That happens to fit in a card slot. Big pain, but it works good. For what you are doing, you are going to probably need 100's of gigbyte of storage, so you have to get at least 74 gig drives, or buy a lot of enclosures.....
 
thanks for the reply, that's all good to know. I'm guessing you needed a power supply and had to switch it on seperately, but the rest is good news.

I'll prolly build a dual athlon system, since I love my current dually, and drop the 200 bucks on a nice card, then aim for like 100-200gb of storage. The main purpose of it will be a temp drive so I can capture at high speeds like 30 hours of video, then transfer it to a much bigger (and slower) ide raid if necessary. I'm thinking many 10k 9 or 18gb drives, i wanna use that bandwidth! What's the limit on one channel, 16 drives?
 
I have 5 18 gig drives, and its not even 100 gig of storage, and you need at least 200. The problem is getting that many drives in the case, and the heat (as well as not many drives fit) You need space between the drives for the air flow, and I doubt you get get more than 5 or 6 drives in an old tower like I did due to airflow. (not to mention all of the power connectors.) I saw a 5 bay professional tower with cooling for $200, which is why I built mine. But with 6 drives, even at 18 gig, you are barely over 100 gig total ! I would say the minimum would be 36 gig drives, but 74 would be much better. 4 74 gig drives would get you close to 300 gig total, and you COULD fit that in most 486 cases.
 
occasionally on ebay you see these old full tower atx cases with 10 5.25" drives for like 1 dollar plus 40 shipping. If i go nuts on the number of drives i'd get one of those crazy things, and maybe mod it to fit more drives. I am curious though, what kind of transfer speeds would I get with a big raid of smaller drives vs a small raid of bigger drives? I want to be able to get at least 160mb/s to utilize the bandwidth, and since i'd be using RAID-5 there's be a performance hit.
 
Use raid0, its faster, and you don;t loose the space for the bit-checks. But again, you need space between the drives for cooling. I don't think those 10 bay monsters have the room. Even so, 10 18 gig drives would only be 180 gig. Go for at least 36 gig.
 
Some SCSI vendors - some have cables, etc. to build a SCSI drive tower from a normal case.

hypermicro.com (may offer free ground shipping if you mention www.storagereview.com - check the SR site for the latest offer)
centrix-intl.com
pc-pitstop.com (also offers PayPal)
scsi4me.com (offers PayPal as a payment option)
and I can usually find stuff for low bucks on eBay.
 
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