TeraByte File Server Project - Drive Cables

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The project described in this web page was started in May, 2001. The product information in this web page (components to use) is current as of January, 2002. The information in this web page provides the knowledge, and ideas necessary to build a functional TeraByte file server. For more information on current file server offerings, please look here.


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Drive Cables

In a project of this nature, there are a lot of drive cables. In order to preserve your sanity, I strongly suggest that the cables be individually identified on each end. The easiest way to do this is to assign a letter to each controller, and write that letter, followed by the controller channel number (1-8) on the cable.

Due to the size of this case, standard UDMA-100 cables can't be used (they're only 18" long). Because of this, it is necessary to use 40-pin 36" IDE cables. These will cause the drives to all run at UDMA-33. This drop in peak bus speed will usually have negligible effect on the throughput of the system, due to the OS buffering, and the intelligence of the 3Ware disk controller. The proper cables can found at CDW, as part number 135210. Any similar cable should work. If necessary, the cable can be shortened by cutting it after the first drive connector. If the cable must be shortened more, it may be done as described below.

If necessary, it is possible to use UDMA-66 cables, but the price of the cables increases significantly. 3Ware sells 24" and 36" UDMA-66 cables. The quality and reliability of these cables is excellent (I've used them with 3Ware controllers, Promise controllers, and motherboard IDE ports). Additionally, CDW carries a 42" 80-pin IDE cable (Part Number 267800) that has been shown to function well. This cable is made by Belkin, one of the leaders in the cable business.Other long UDMA-66 and UDMA-100 cables have been used with intermittent results.

These cables are quite long, and may cause issues if left loose. Don't cut the cable, and only use the two end connectors. Fold it gently into an 'S' shape, and wrap electrical tape around the folded section (wire ties may also be used if you're careful). This will shorten the cable in a safe manner. The cable should have some slack in it, but not too much.

Here are some pictures of different systems, showing how the cables should look when you're done. There is a significant effort made to keep the cables together, and not just flopping around. This is done for two reasons. First, the cables are less likely to be in the way if maintenance is required on the system. Second, a bundle of cables has the same effect on airflow that a single cable does, which is much less then the effect of a wad of cables. Keeping the cables orderly should improve airflow, thereby keeping the system cooler, and probably more reliable.

This is a fairly simple system. It has 2 Promise Ultra-133TX2 cards in it, and 8 Maxtor 160GB drives. The cables are all wire-tied into a firm (not tight) bundle, and the bundle passes up behind the drives. In the bottom of the case, it can be seen that a few special folds are needed to get everything to hook up correctly, but the result is worth it.
This is a more complex system with 2 3Ware 7810 controllers and 12 Maxtor 120GB drives in removable trays. This case is a smaller version of the case that SDSC used for their system. Very little of the cabling can be seen here, but the cabling you can see is orderly.
This is a closeup of the cables coming off the controller cards. The cables are taken through a sweeping bend to get to the other side of the case.
This is the drive side of the case. Again, there is no clutter. The cable runs are wire-tied together into a single bundle going up (and down) the line of drives. There are a few loops, as there was plenty of space, and I didn't want to bend the cables tighter then I had to.
This is a tight and complex system with 2 3Ware 7850 controllers, 16 Maxtor 120GB drives in removable trays and a Seagate 36GB SCSI system drive. The case is a rackmount 4U (7" high) case, which accounts for how tight everything is. Again, the cable bundles make sweeping bends, but averything is orderly.

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