- May 23, 2010
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Intro To SCSI (formerly SASI)
After reading this you should know everything needed to setup a simple SCSI system. 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 however it may not work.
When it fails to work it gets tricky to troubleshoot. 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.
Get acquainted with the parts.
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.
Background info
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, 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.
Info on device IDs
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 a 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.
Install hardware
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.
Connect the devices
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.
Firmware setup
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.
Install/configure operating system
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).
Troubleshooting tips and tricks
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.
Your done
If it all worked correctly you should have an OS installed and working and possibly additional storage.
SCSI is not used a lot because it is about the same speed as 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.
After reading this you should know everything needed to setup a simple SCSI system. 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 however it may not work.
When it fails to work it gets tricky to troubleshoot. 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.
Get acquainted with the parts.
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.
Background info
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, 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.
Info on device IDs
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 a 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.
Install hardware
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.
Connect the devices
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.
Firmware setup
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.
Install/configure operating system
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).
Troubleshooting tips and tricks
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.
Your done
If it all worked correctly you should have an OS installed and working and possibly additional storage.
SCSI is not used a lot because it is about the same speed as 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.
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