Questions:
- What does DDS stand for?
- Is DDS different from DAT?
- Can I use a 125m (DDS-3) tape in my tape drive that uses 120m (DDS-2) tape?
- How does one enable or disable compression on a DDS tape drive?
- Can tapes be exchanged between my DDS tape drive and DDS tape drives from other manufacturers?
- My DDS tape is having Read and Write problems, how do I fix it?
- My DDS tape drive won’t response to any SCSI commands.
- I cannot reach full capacity on my DDS tapes, why?
- How do I eject a stuck tape? Why won’t my DDS tape drive accept or recognize tapes?
- Why won’t my DDS tape drive read back-ups made on another system?
- My tape won’t eject. If I hold up the dust flap open while ejecting, the tape will eject OK.
- Why can I do a successful backup on some days, the backup fails on other days?
- Why do I get bad block or bad media errors? What can I do?
- What does it mean when I get a "data mismatch" error"?
- What causes SCSI timeout?
- Why do I get CRC errors on my DDS tape drive?
- How do I set SCSI ID for the DDS tape drive?
- How do I terminate my DDS tape drive?
- Drive termination – Active vs Passive.
- What do I do if my DDS tape drive is not detected?
- My DDS tape drive can’t read back my DDS tapes. Why do I get SCSI error messages?
- What caused my DDS tape drive to snap the end of the tape off the spool?
- Why my DDS tape drive LEDs will not flash upon power up?
- What do the flashing sequences of LED lights on my DDS tape drive indicate?
- How do I increase my DDS tape drive performance?
- Can a LVD tape drive be used in an HVD environment and vice versa?
- Do I need to have all tapes in the magazine in order to use the DDS Autoloader?
- What do I do if my LCD shows an Illegal Magazine Configuration on a DDS Autoloader?
- How do I remove a tape magazine that will not eject from a DDS autoloader drive?
- Does the DDS tape drive include any software or media?
- How often does my DDS tape drive need cleaning?
- How do I determine the firmware revision of my DDS tape drive?
Answers:
What does DDS stand for? DDS is the abbreviation for Digital Data Storage. DDS drives are also called 4 mm tape drives or DAT streamers.
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Is DDS different from DAT? DDS evolved from DAT (Digital Audio Tape) and uses the same recording principle as home video recorders. However, instead of recording analogue video signals, it records digital data. Both use the same type of tape, but computer grade DDS tape must meet strict ANSI standards. This means it has a much lower BER (Bit Error Rate) than most DAT tape and is therefore more reliable. Unlike audio DAT tape, DDS is certified "error free".
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Can I use a 125m (DDS-3) tape in my tape drive that uses 120m (DDS-2) tape? No. DDS2 drives will automatically eject DDS3 tapes. Drives and Media are only backwards compatible. Please refer to your tape drive manual for more specific informations regarding tapes compatibility.
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How does one enable or disable compression on a DDS tape drive? The compression can ONLY be set in the software OR the hardware, not both. If the compression is to be set on the hardware, you will need to set the jumper or dip switch accordingly. The methods to control compression are different depending on the product.
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Can tapes be exchanged between my DDS tape drive and DDS tape drives from other manufacturers? Yes! DDS1, DDS2, DDS3, and DDS4 standard formats allow the use to interchange tapes between different manufacturer drives. However, the user needs to ensure consistency in terms of the format and compression being used. For example, if the tape is written in compressed format, it needs to be read using compression (i.e. drive compression needs to be enabled if it supports compression). If the tape is written in a DDS2 format or DDS3 format, it needs to be read using a DDS2 drive or DDS3 drive. So, tapes written in DDS3 format cannot be read using DDS1 or DDS2 drives. In general DDS3 drives can write and read DDS1, DDS2, and DDS3 media.
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My DDS tape is having Read and Write problems, how do I fix it? The most common cause of this is dirty heads or bad media. Try a cleaning cartridge and then use new media as the old media may be contaminated. Retensioning the tape may also improve performance. The heads should be cleaned with a DDS Cleaning Tape at least every 24 hours of tape drive usage. Heads must be cleaned regularly to ensure reliable performance. If long periods go by without cleaning, foreign material will build up on the heads and a cleaning tape may no longer be effective. In this case the drive will need to be returned to an Authorized Service Center.
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My DDS tape drive won’t response to any SCSI commands.
If a Scsi Bus Reset doesn't cause the drive to reset, check the cabling. If the Scsi Bus Reset works, check for possible ID conflict or improper termination.
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I cannot reach full capacity on my DDS tapes, why? Your tape drive is a streaming device. If the data buffer in the drive becomes empty during the backup process the tape will continue moving thus leaving areas on the tape with no data and reducing the tapes capacity - This can be caused by poor system performance or by backing up over a slow or busy network. Incorrect SCSI configuration can also cause data bottlenecks, for best performance it is recommended to configure the tape drive with a dedicated SCSI controller. Dirty heads and poor media condition can cause write errors, the data will then have to be written again, this also reduces tape capacity - Be sure your drive heads are clean and the media is in good condition. Due to the built in head cleaning mechanism on all AIT drives, only under extreme environmental conditions should it be necessary to clean the heads on an AIT drive. If you are using data compression, remember that some files do not compress very well, ie: MPEG, JPEG, PDF etc. If your drive has built in hardware compression enabled be sure that you do not have the backup applications software compression enabled also.
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How do I eject a stuck tape? First, make sure the correct type of tape is being used. Try issuing a SCSI bus reset or power the drive OFF and back ON to override this condition. Disconnect the data cable from the drive to determine if the cable or connection may be the problem. If this does not work and if it is absolutely mandatory that the tape cassette be removed prior to returning the drive for repair, an emergency cassette removal procedure can be performed. See tape drive manual or contact drive manufacturer technical support for further assistance.
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Why won’t my DDS tape drive accept or recognize tapes? Try different media. Ensure that you have the latest firmware version for your unit. Check that the jumper settings are all set correctly. Make sure your SCSI card is detected and has the latest updates.
Why won’t my DDS tape drive read back-ups made on another system? Ensure that the compression method used to make the tape is the same as the one being used to read it. Make sure the back-up program on the reading computer is the same type or newer than the one which created the tape(s).
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My tape won’t eject. If I hold up the dust flap open while ejecting, the tape will eject OK.
Make sure the face plate is installed correctly. When fitting the face plate the "dust flap" must be held open and the small "dust flap actuator arm" on the side of the drive must be resting forward. If this is not done correctly then the dust flap will not open and allow the tape to eject.
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Why can I do a successful backup on some days, the backup fails on other days? Replace the tapes that fail with known good tapes or new tapes if possible. The particular tapes that are not successfully backing up are most likely defective.
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Why do I get bad block or bad media errors? What can I do?
First of all, make sure to use drive manufacturer recommended media. Try retensioning the tape. This is an important procedure whenever encountering any type of problem with your tapes.
Tape Retensioning the tape cartridge is always recommended for optimal performance, particularly if using a new tape, after exposure to temperature changes or shock. Retensioning restores the proper tape tension to the media and removes unwanted tight spots that develop naturally on tape. If a tape cartridge has not been used for over a month, you should retension the cartridge before using it. If you ever have a problem reading a tape, retensioning may solve the problem. See your software manual, or refer to your software's online help for instructions on tape retensioning. If the tape is dropped, retension before using it.
Note: In some cases, it may be necessary to retension a tape several times. Try another tape after exiting, then re-starting the software. Try initializing the tape through backup software to see if that solves the problem. If not, do a Long Erase (if your backup software permits) of the tape before the next backup is attempted. This will take over 1 hour and will completely wipe the tape. It will leave the format intact. Replace the tapes with new ones, clean drive several times in a row, cold boot the system to reset the drive and check SCSI settings to make sure they are set at the suggested settings for the drive.
CAUTION! A Long Erase or Initializing the media is not an option if you are attempting to restore from the tape in question. Either procedure will remove the tape header and the data will no longer be retrievable from that tape.
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What does it mean when I get a "data mismatch" error"? This is caused due to the file was open and/or changed between the time of the backup and verify.
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What causes SCSI timeout?
SCSI time outs occur when the signal sent from the backup source (through the SCSI card to the tape drive) is lost or greatly diminished in strength. The tape drive does not understand what it is being asked to do and a SCSI time out occurs. To stop SCSI time outs, do the following:
Check your cabling. Make sure both ends of the SCSI cable are firmly fastened in the connector. If the tape drive is the terminating device make sure there are no empty connectors between the tape drive and any other device that may be on the cable.
Make sure you have the latest drivers for your SCSI controller. Drivers are provided by your SCSI card manufacturer.
Check your SCSI settings to make sure they are set to the drive manufacturer suggested settings.
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Why do I get CRC errors on my DDS tape drive?
CRC errors indicate one of a few things:
Dirty drive head.
Bad tape. The tape may have bad sectors or is getting old and the coating material is coming off or has stretched due to high heat and/or use.
Bad tape drive. A bad tape drive can be manifested any number of ways including CRC errors, I/O errors and filling up tape rapidly.
Termination and other cabling problems.
Problem with SCSI controller card and/or transfer rate is set up to fast for the tape drive.
Bad or outdated drivers.
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How do I set SCSI ID for the DDS tape drive? SCSI ID can be set by jumpers or DIP switches. Refer to your tape drive manual for instructions specific to your drive model. For external model, SCSI ID switch is located at the back of the unit.
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How do I terminate my DDS tape drive? Usually through a jumper or a DIP switch. For external model, an external terminator is required. Please refer to your drive manual for instructions specific to your tape drive model.
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Drive termination – Active vs Passive.
Both physical ends of a SCSI bus must be terminated. There are two types of termination, Active and Passive. Depending on tape drive model determines what type of termination is used and how it is set.
Communications along a SCSI bus is conducted via electrical pulses. When a signal reaches the end of an non-terminated bus, it reaches open air. Air has an exceptionally high impedance, thus causing the signal to reflect back into the bus creating an echo effect. Echo noise in the line will cause significant data errors. In order to prevent this, terminators are placed at both physical ends of the SCSI bus. These terminators produce an impedance which matches that of the cable. The presence of matching impedance effectively eliminates signal echo. Passive termination utilizes a terminating resistor pack which reside on the bus to minimize reflections at the end of the cable. The terminator does not regulate the power for termination but relies on the interface card to provide consistent power. A resistor (passively) converts the supplied (+5 volts) to a corresponding amount of impedance.
If there is a fluctuation in the voltage supplied to it, the resistor will consequently send a fluctuation in impedance. A passive terminator simply provides an impedance that's close to the impedance of the cable. If the impedance is not relatively constant, it is likely that data errors will occur. Active termination works to control the impedance at the end of the SCSI bus by using a voltage regulator, not just the power supplied by the interface card. Because it is active, regulating the power that it gets from the interface card, active termination is more stable than passive termination. A voltage regulator has the ability to (actively maintain a constant amount of impedance regardless of fluctuations in the power supplied to it. Although Passive termination is suitable for a standard SCSI-1, or SCSI-2, Active termination was designed for use with a Fast SCSI-2 (10 Mhz) bus or more.
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What do I do if my DDS tape drive is not detected? Verify the drive is running in a supported environment and connected to a supported host adapter. Check your software and hardware documentation for a compatibility listing. If your drive is an external model, confirm that all the cables are plugged in correctly and the power switch is on. Verify that the drive, host adapter and user settings are set correctly according to the respective installation manuals. Make sure that the cables are properly connected and that they are securely attached. Confirm that the drive and host adapter settings do not conflict with other devices installed in your system. Ensure that drive termination is properly set. If your drive is connected to a supported host adapter, be sure you have the appropriate ASPI drivers loaded. Cycle power to the tape drive without a tape cartridge inserted in the drive. Insert a tape into the drive, verify that the "tape inserted" drive light comes on and then eject the tape to ensure it is working properly.
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My DDS tape drive can’t read back my DDS tapes
Poor quality media, worn media or dirty tape drive heads. Insert a cleaning tape, then use brand new media as old media may contaminate the heads again. If long periods go by without the use of a cleaning tape, foreign material will build up on the heads and a cleaning tape may no longer be effective. In this case the drive will need to be returned to an Authorized Service Center for cleaning. If tape was written in a different drive, one of the drives may be incorrectly aligned - Try a back up and restore using the one drive, tape, backup application and operating system. Incorrect SCSI configuration can also cause these types of problems, for best performance it is recommended to configure the tape drive with a dedicated SCSI controller.
Why do I get SCSI error messages? Reset the unit. Ensure that the SCSI card is detected, you have the latest firmware, and the latest updates for the card. This could mean that the SCSI card is not working with the tape drive or is defective. Replace it with a compatible card. Check for proper SCSI termination.
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What caused my DDS tape drive to snap the end of the tape off the spool?
This is a rare issue, usually caused by the following:
Over use of the tape. Tapes have a life expectancy of approximately two to three years.
Usage of the tape may have occurred outside the bounds of the specification. In other words, the recording took place in an environment that was too hot or too humid. Make certain the room is cool and has a low level of humidity. Drive Related Issue. This could be an issue caused by the tape drive not properly sensing or reading the end of the tape. The tape will remain inside the drive when the media has snapped.
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Why my DDS tape drive LEDs will not flash upon power up? Power off the drive, wait five seconds, then power ON again, and check if the LED power on flash sequence is OK. If problems persist, the fuse is probably blown, and the drive needs to be returned for service. Blown fuses are a common problem when power is applied in reverse, or the power supply is out of regulation on the 5V or 12V DC lines.
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What do the flashing sequences of LED lights on my DDS tape drive indicate? The LED lights flashing allow you to view the activities and possible errors on a tape drive. Please refer to the drive manual for informations specific to your tape drive model.
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How do I increase my DDS tape drive performance? Many SCSI controllers have their default BIOS settings optimally configured for hard drives and other types of logical devices. However, tape drives are streaming devices and generally do not use the same settings as these other devices. If configurable, disable the Synchronous Negotiation option for the entire SCSI host adapter or the particular device. Many modern SCSI host adapters have this configurable through the BIOS or via a jumper/switch setting. Also, if possible, set the bus transfer rate to the smallest allowable, working your way back up until the tape drive functions as expected. Many SCSI host adapters can be set to data transfer rates higher than most drives can accurately handle.
Initiate Sync Negotiation - No
Initiate Wide Negotiation - No*
Maximum Transfer Rate - 5 Mbytes/sec*
Enable Disconnection - Yes
Send start unit command - No
*If the tape drive is a Wide device, set Initiate Wide Negotiation to Yes and Maximum Transfer Rate to 20 Mbytes/sec.
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Can a LVD tape drive be used in an HVD environment and vice versa? No. Install an HVD drive only in an HVD environment and an LVD drive only in an LVD environment. Do not mix HVD and LVD devices. Incorrect mixing of device types may result in damage to the device or system. The signals on the interface are incompatible. Look at the label above the drive's SCSI connector to determine if the drive is an HVD or LVD model.
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Do I need to have all tapes in the magazine in order to use the DDS Autoloader? Yes, all tapes must be in the magazine in order for the DDS Autoloader to operate properly.
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What do I do if my LCD shows an Illegal Magazine Configuration on a DDS Autoloader? This error usually occurs when a tape is caught in the magazine, the magazine is not full, a tape is inserted upside down in the magazine or a label or a portion of the label is covering the recognition tabs on the bottom of the cartridge's front side panel.
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How do I remove a tape magazine that will not eject from a DDS autoloader drive? Please check that the Prevent Media Removal has not been enabled. A SCSI Bus reset or power OFF/ON of the autoloader should disable Prevent Media Removal. If a fatal error is displayed on the front panel LCD, the tape magazine may not eject. A SCSI Bus Reset or power cycle may clear the error condition allowing tape magazine removal. If this does not work and if it is absolutely mandatory that the tape magazine be removed from the autoloader, an emergency tape magazine removal procedure can be performed.
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Does the DDS tape drive include any software or media? For details on available software and media, please contact either your local dealer or drive manufacturer.
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How often does my DDS tape drive need cleaning? Proper maintenance is important to keep your DDS drive working properly. A routine of regular cleaning helps reduce errors due to environmental contaminants such as dust, carpet fibers or airborne debris. If excessive dust or debris from the tape media collects at one or more of the tape heads, your drive may not be able to read from or write to tape. To avoid this situation, you must clean the tape heads on your DDS drive in the following circumstances: when using a new data cartridge, clean the drive every four hours of tape movement until the tape has been used from beginning to end. After every 25 hours of read/write operations on a DDS-1, DDS-2, or DDS-3 tape drive. After every 25 hours of read/write operation using DDS-1 or DDS-2 tapes or every 50 hours of operation using DDS-3 or DDS-4 tapes on a DDS–4 tape drive. If the Clean LED lights up or flashes or the Media LED flashes during drive operation.
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How do I determine the firmware revision of my DDS tape drive?
Use your SCSI controller card, the controller card may have a diagnostic utility or switch which will allow you to determine the firmware level of peripherals (including the tape drive) attached to the card. See your controller card documentation for information. Another way is to use tape drive manufacturer’s diagnostic utility which can be downloaded from the manufacturer’s web site. If none of the above is available, try the following methods:
*Windows 9x
From Windows 9x opening screen:
Click START - SETTINGS - CONTROL PANEL
Double click the Systems Icon; choose the Device Manager tab.
Double click on Tape Drives, then highlight the appropriate tape drive name.
Click on Properties, then select the SETTINGS tape. You will see the Firmware Version.
Or
From Windows 9x opening screen:
Click START - RUN- type REGEDIT. Click OK.
Drill down: HKey_Local_Machine- Enum - SCSI - Name of Specific Tape Drive
Note: The Tape category under Enum will not give much information.
Under the Tape Drive there will be a controller designation.
Click the controller entry; look in the right frame for Revision Level. This is the firmware information.
*Windows NT 4.0 / 2000
If the drive is attached to a Windows NT 4.x / 2000 server or workstation:
Click on START - SETTINGS - CONTROL PANEL and select Tape Devices.
From Tape Devices, select PROPERTIES and then the SETTINGS tab.
The firmware revision will be displayed.
OR
Access the Registry Editor.
Click on START | RUN, then type REGEDT32.EXE and click OK.
Select: HKey_Local_Machine on local machine.
Drill down: Hardware - DeviceMap - SCSI - SCSI Port 0 - SCSI Bus 0 - Target ID x
- Logical Unit ID x (usually 0)
Target ID is the SCSI ID of the tape drive.
If there are multiple controller cards in the system, you may need to select an alternate SCSI Port.
Look at the right frame under Identifier to see the firmware.
*Novell Netware
The program BEDIAG.NLM will return firmware information. This may be obtained from the self-
extracting BEDGNLM.EXE file. Load and run this NLM with the switch "/s/w" to get just SCSI bus
information. Running the NLM will create an output file called BEDIAG.FAX. Find the line that lists the
tape drive. The firmware version will be listed at the end of this line.
*Dos or Windows 3.X
The file ASPIINFO.EXE will scan ASPI compliant third party controller cards for firmware and other
information for devices on the SCSI bus. The appropriate ASPI manager must be loaded at bootup in the
config.sys file. Or through the backup software configuration settings.
*Unix
Check your controller card or operating system information for a possible SCSI interrogation utility. If
possible, boot to DOS or any of the previously mentioned operating systems, and use the procedure for that
operating system.
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