Introduction: Intro to SCSI (formerly SASI) Configuration.

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After reading this instructable you should know everything needed to setup a simple SCSI system.
You may use this for many reasons like working on an old system that uses SCSI, for a job. If your a gamer and IDE is too slow and just can't or don’t want to go to SATA. Allot of older servers used SCSI and are being replaced during upgrades. You may be able to get one of these for nothing or a little cost. This could possibly become a file server for home or a small business that performance isn’t that important.
This is primarily for internal devices however for externals many of the same concepts apply. This was my first experience with SCSI. During this I learned this: it may sound simple in theory to setup and be fairly simple to configure however it may not work. When it fails to work it gets tricky to trouble shoot. I will address some common problems and troubleshooting tips also in this. Hopefully this will help you to successfully complete your SCSI setup. I had some unusual issues during my experience and will include them just incase someone else has a similar issue.

Step 1: Backgrond on SCSI

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SCSI stands for Small Computer System Interface (this is pronounced as skuzzy.) this is a type of communication bus that computers use to communicate with drives internal & external, scanners, printers, etc. this is similar to IDE and SATA in that it does the same thing. The difference is in the cabling and the protocols and circuitry. As well as speed and signaling method parallel like IDE, most SCSI, or serial like SATA, USB. IDE however doesn't allow external devices like SCSI or SATA. All these systems have different versions witch change the caballing as well as the speeds of data transfer. SCSI comes in many versions with different speeds, cabling and the operating frequency. This link describes the different version in a table, http://en.wikipedia.org/wiki/SCSI. There are also different voltage versions of SCSI. HVD (high voltage differential), LVD (low voltage differential), SE (single ended). HVD is also referred to as differential SCSI the use of LVD or SE devices on a HVD SCSI chain will likely damage the devices that are LVD or SE and possibly the HVD controller. LVD and SE are quite similar except in their caballing. SE is low end and uses flat ribbon cables with relatively low speed. LVD uses better twisted pair type cables. Both LVD and SE can run on the same bus (cable), but the LVD will be limited if using the SE type cabling.

Step 2: Get Aquanted With the Parts.

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Here are the most of the parts of a SCSI system. Parts list: SCSI controller, SCSI cable, intermediate devices (maybe) (backplanes, adaptors, switches), drives, termination either in form of terminator or on drive enabled by jumper. The pictures follow this list in order. I did not include a SCSI switch this is basically a box with three + SCSI ports of some form. The switch is normally a dial that will select two ports to connect. Normally there is one in/out port and the rest can go to different devices. This selects a device to use.

Step 3: Background Info

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Going from the motherboard to drives follows like this. The SCSI controller either a card or integrated in the motherboard. This connects to a SCSI cable. This cable then connects to the drives and/or intermediate devices. All the drives must have power and a SCSI ID. All parts including the controller must have a SCSI ID and support the same standard, For instance: HVD, LVD, and SE SCSI. The speeds can be different as long as the standards are the same. All parts will operate at the speed of the slowest component connected to that particular SCSI bus.

Step 4: Info on Divice IDs

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Device IDs are one of the most important parts in the SCSI system. If a device does not have one it cannot be addressed by the bus. If it is the same as another neither device will function correctly. How a device ID is set can vary however it is normally done in either firmware (this is common for the controller), or by a jumper, dipswitch, number switch. In firmware enter the firmware using the key specified at boot or the product documentation. This will most likely be just for the controller. The drives are set the other way. A diagram on the drive or in the documentation will show the pins to use. To set an ID find the pin with the desired number like 2 put a jumper on those corresponding pins as illustrated in the diagram. (Most external devices will use a form of 2 push buttons with a wheel with numbers on it. this number is the SCSI ID on that device. There are 2 ranges of IDs to use 0-7 and 8-16. Some systems only allow 8 devices so the first one is used, else they can all be used. This is mainly dependent on the SCSI standard. This depends on whether the SCSI bus is 8 or 16 bit wide. These use 0-7 or 0-16 respectively.

Step 5: Install Hardware

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1. Take your devices and configure the ID and other settings as desired according to the device label or documentation.
2. Install the devices in the case. Use adaptors if needed to mount a smaller drive in a 5 inch bay.
3. Install the cable in the case avoiding sharp corners that could cut the cable. As well avoid twist and sharp bends as much as possible.

Step 6: Conect the Divices

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4. Connect the cable to the drives. The last drive if on the end of cable must have termination enabled.
5. Terminate the bus using a terminator or the last device on the cable (This is normally done using a jumper (if device is internal) else a special plug if external in the 2nd port).
6. Connect the other end of the cable to the controller. (If not installed install this now preferably configured already if it uses jumpers for configuration)
7. Connect the system to power and main peripherals.

Step 7: Firmware Setup

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8. Turn it on.
9. It should boot the controller firmware should display status and any devices it finds.
10. If any problems then use the key to enter the controller firmware. Make sure that there are no conflicting IDs and the controller has an id. (Normally the controller has the highest ID.) Also if you’re using one port on the controller make sure that termination on the controller is enabled.

Step 8: Install/configure Operating System

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11. If installing an OS on SCSI drive(s) you may require the SCSI driver fro the controller. Before it will install you provide the driver normally using 3.5 floppy. Disk when the install says press f6 or something to load 3rd party driver. The files should load then install will proceed as normal.
12. After the OS is installed configure it as needed, and don’t forget to format the SCSI hard drives and assign a mount point (either letter or file).
13.  If any drives fail to show in the disk mgmt or disk part utilities on the next reboot enter the SCSI firmware select the device and do a format (this format is normally low level type).

Step 9: Toubleshooting Tips and Tricks

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Troubleshooting tips
1. Every device including the controller needs a SCSI ID. Normally controller is the highest ID.
2. Every drive must have power either via Molex or the SCSI backplane if SCA connector drives.
3. Each end of a bus must be terminated in order to function properly. The controller is normally one end the other is normally a drive with termination enabled or a termination plug. However controllers can be set up in the middle and a termination at each end. The terminations must be at the very last connector on the cable. If a drive is configured by jumper or dipswitch to termination on (enabled) the drive should function as a terminator. If it fails to work correctly remove the drive from the end and install a termination plug in its place to verify that is the issue. If desired and possible move the drive to another port. If this works verify the configuration using documentation. If it still fails move the drive to a different connection if possible.
4. also don't forget documentation can be a big help.

Step 10: Your Done

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If it all worked correctly you should have an OS installed and working and possibly additional storage.
This instructable has been terminated. (The end) Pun intended because SCSI is terminated at the end (LOL).
SCSI is not used a lot because it is slower than SATA now and hard to use. With this you may be able to recycle an old system to make a NAS or file server. You may find a system from some place that uses servers and is upgrading some servers. (SCSI is popular for older servers very few desktops used it.) This can keep valuable and possibly toxic materials out of the environment.

Comments

PCelec (author)2012-08-11

just did some modifications as sugested in the instructables clinic. fixed all isues that i found with it. then republished.

PCelec (author)2012-08-09

I know this is quite technical, but i'd like to know what readers think of this. I know SCSI is becoming less popular than SATA now. However i'd like to see what people think of this and  if it's helped anyone. so far my instructables have been failey short and often with gramatical type mistakes. I feel this is my most complex and hopefully best instuctable yet. so would like to know how i did, and if i made any mistakes so that i can fix them in this and my future instructables.

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Bio: Computer/ electronics guru. Hobbies are: electronics mainly destroying things and then making something new or learning how things work. I have been getting into fixing ... More »
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