View Full Version : SCSI Dual Channel and Gbit Ethernet JBOD

09-22-2003, 10:03 PM
I have 4 drive set stripped across two channels of my built in U160 controller (P4DC6+ with onboard Adaptec AIC-7899W dual channel Ultra160 SCSI controller). If I were to add some drives and re-stripe to end up with 4 drives internal as one set and 4 drives stripped as external set would my real time performance be diminished? IOW, does stripping across the dual channel U160 make much difference compared to having stripes on only one channel?

Any suggestions for external hardware would be appreciated as well, like - case, powersupply, cables, raid controller if needed (?), etc.

Has anyone tried using a SAN setup or a JBOD rack with a Gigbit copper ethernet connection with any success. I've talked to Rorke several times but they say Newtek has not supplied the info they need to support VT3 with their SAN's even though they have talked to them a number of times. To save money for a single user setup, I would prefer to build my own rack if possible at first. Any comments are very welcome!


09-23-2003, 09:32 AM
Having installed many systems with the P4DC6 mobo, I can help you with a few questions.

4 U160 drives should be getting around 115-120 mb/sec. I saw no difference between running them on a single channel or split at the time I tested them.

BUT running 6 drives with 3 on ChA and 3 on ChB would get me around 230 mb/sec on disktest. This was a substantial difference in performance.

In your instance, I would put all the internal drives on one channel and patch your other channel to the outside. Take your outside channel to a Scsi case with 4 more 160's in it. Then you have a choice of striping them all together in one large RAID or to stripe each set of 4 independently. The advantage of the large Raid setup is speed and space. The disadvantage is loose one drive and your toast.

An answer to your question is no about performance diminishing. If anything performance will increase. If you can get 3-4 streams off of a 4 drive stripe, then add two stripes together and you will be getting 6-8 streams out of your complete system.

And then there are the U320 drives.... Crazy fast but choked down on a P4DC6 unless you spend $400 on an Adaptec 39320 scsi controller.

At NAB I went around to all the major and minor players in the SAN market. The thing I kept running into was that technically any SAN will work with VT, but the performance will not be as good as local drives. The best SAN connection is FiberChannel but it tops out around 200mb/s. Our recent 4 drive U320 system got 300 mb/s. And SANs are sooooooo [email protected][email protected]!

Since I have done exactly what you are thinking about, then give me a call and I will help you the best I can.

09-23-2003, 12:57 PM
For external SCSI striped set I'm interested in the
StarTech.com External Drive Case for (8) 5.25" SCSI3 Devices (P/N SCSI3CASE8) (http://startech.com/ststore/itemdetail.cfm?tab=e&ProductID=SCSI3CASE8&topbar=topbara.htm).

Does anybody have any knowledge of the StarTech brand and/or this particular external SCSI expansion box? The price looks great at approx $288. The only drawback I can see is the need for 3.5" brackets.

Thanks in advance...Mark

09-23-2003, 01:16 PM

Give me a call and I might be able to fix you up.

I have a 9 bay external U160 SCSI case for $275
I also have the same case in an U320 version for $330 which is what I would suggest going with.

I can send you some pics if needed.

I would recommend using a combination of rails and fans for the hard drives. The only disadvantage is the ambient noise the unit will generate. I have some kits with Hard Drive rails and a triple HD fan for $19 ea.

I have used this case for building RAIDs and CD/DVD duplication systems. Very solid and well built. Should last for a long long time.

Let me know if I can help.

09-23-2003, 01:17 PM
Here is the hard drive kit I was speaking of:

09-26-2003, 11:22 AM
Looks like some good options. I'll pop you an email using the contact address from your website. Thanks...Mark

09-26-2003, 11:35 AM

If you're getting 300mb/sec on a 4 drive U320, I should expect more than 90mb/sec on a 3 drive U320, right?