I was given two used SCSI DDS-4 tape drives, and I am testing them for use in making backups.
One is an HP DAT40i (aka C5686A, C5683A) and the other is a Compaq SDT-10000 (EOD006, .
I find that each drive can read the tapes that it writes, but that neither drive can read the tapes written by the other.
I have put a cleaning tape through each drive, and the firmware of each drive is up-to-date. Both drives pass the diagnostics in the HP Library & Tape Tool.
Shouldn't these drives be able to read each other's tapes? Do I need to adjust some parameters, or should I assume that at least one of them is defective?
>I was given two used SCSI DDS-4 tape drives, and I am testing them for use >in making backups.
> One is an HP DAT40i (aka C5686A, C5683A) and the other is a Compaq > SDT-10000 (EOD006, .
> I find that each drive can read the tapes that it writes, but that neither > drive can read the tapes written by the other.
> I have put a cleaning tape through each drive, and the firmware of each > drive is up-to-date. Both drives pass the diagnostics in the HP Library & > Tape Tool.
> Shouldn't these drives be able to read each other's tapes? Do I need to > adjust some parameters, or should I assume that at least one of them is > defective?
I'm testing using tar and diff for both. Also using the same SCSI adapter and the same computer for both. I test with only one tape drive installed at a time.
I test whether drive 1 can read the tape it has written, then I shut down, swap drives, and try to read the same tape with drive 2 and find that it can't read it.
Bill wrote: > Are you using the same software to test each?
> "Matt" <m...@themattfella.xxxyyz.com> wrote in message > news:4KWXj.234$Vf.88@fe093.usenetserver.com... >> I was given two used SCSI DDS-4 tape drives, and I am testing them for use >> in making backups.
>> One is an HP DAT40i (aka C5686A, C5683A) and the other is a Compaq >> SDT-10000 (EOD006, .
>> I find that each drive can read the tapes that it writes, but that neither >> drive can read the tapes written by the other.
>> I have put a cleaning tape through each drive, and the firmware of each >> drive is up-to-date. Both drives pass the diagnostics in the HP Library & >> Tape Tool.
>> Shouldn't these drives be able to read each other's tapes? Do I need to >> adjust some parameters, or should I assume that at least one of them is >> defective?
> I'm testing using tar and diff for both. Also using the same SCSI adapter > and the same computer for both. I test with only one tape drive installed > at a time.
> I test whether drive 1 can read the tape it has written, then I shut down, > swap drives, and try to read the same tape with drive 2 and find that it > can't read it.
> Bill wrote: >> Are you using the same software to test each?
>> "Matt" <m...@themattfella.xxxyyz.com> wrote in message >> news:4KWXj.234$Vf.88@fe093.usenetserver.com... >>> I was given two used SCSI DDS-4 tape drives, and I am testing them for >>> use in making backups.
>>> One is an HP DAT40i (aka C5686A, C5683A) and the other is a Compaq >>> SDT-10000 (EOD006, .
>>> I find that each drive can read the tapes that it writes, but that >>> neither drive can read the tapes written by the other.
>>> I have put a cleaning tape through each drive, and the firmware of each >>> drive is up-to-date. Both drives pass the diagnostics in the HP Library >>> & Tape Tool.
>>> Shouldn't these drives be able to read each other's tapes? Do I need to >>> adjust some parameters, or should I assume that at least one of them is >>> defective?
Matt <m...@themattfella.xxxyyz.com> writes: > I was given two used SCSI DDS-4 tape drives, and I am testing them for > use in making backups.
> One is an HP DAT40i (aka C5686A, C5683A) and the other is a Compaq > SDT-10000 (EOD006, .
> I find that each drive can read the tapes that it writes, but that > neither drive can read the tapes written by the other.
> I have put a cleaning tape through each drive, and the firmware of > each drive is up-to-date. Both drives pass the diagnostics in the HP > Library & Tape Tool.
> Shouldn't these drives be able to read each other's tapes? Do I need > to adjust some parameters, or should I assume that at least one of > them is defective?
DDS-4 is DDS-4, but I'm not certain that they would use the same hardware compression technique, if you have that enabled via the jumpers on the drives. You should be able to disable compression using "mt compression 0".
Scott -- Scott Hemphill hemph...@alumni.caltech.edu "This isn't flying. This is falling, with style." -- Buzz Lightyear
Scott Hemphill wrote: > Matt <m...@themattfella.xxxyyz.com> writes:
>> I was given two used SCSI DDS-4 tape drives, and I am testing them for >> use in making backups.
>> One is an HP DAT40i (aka C5686A, C5683A) and the other is a Compaq >> SDT-10000 (EOD006, .
>> I find that each drive can read the tapes that it writes, but that >> neither drive can read the tapes written by the other.
>> I have put a cleaning tape through each drive, and the firmware of >> each drive is up-to-date. Both drives pass the diagnostics in the HP >> Library & Tape Tool.
>> Shouldn't these drives be able to read each other's tapes? Do I need >> to adjust some parameters, or should I assume that at least one of >> them is defective?
> DDS-4 is DDS-4,
I was guessing something like that. I think you are saying that the format is as standardize as say ext3 or fat16.
> but I'm not certain that they would use the same > hardware compression technique, if you have that enabled via the > jumpers on the drives.
Thanks, Scott, I'll try that. So we are expecting/hoping to be able to interchange any non-compressed DDS-4 tapes among DDS-4 drives.
I found the following doc which gives a lot of technical detail on the Compaq (rebadged Sony) drive.
> PRODUCT DESCRIPTION MANUAL > DDS-4 Tape Drive > Model : SDT-10000 > : SDT-11000 > Ver. 1.3 March, 2006 > Sony Corporation > Data Compression For Information Interchange > Adaptive Coding with Embedded Dictionary, DCLZ Algorithm, June 1991 > European Computer Manufacturers Association (ECMA-151)1 > 4. 6 DATA COMPRESSION > The tape capacity is increased by compressing data prior to writing it to the tape. Data compression is a well established > technology for reducing the number of bits used to represent data in order to improve data transfer rate as well as reduce > the amount of storage space consumed by the data. > The SDT-10000/SDT-11000 uses the AK 8320 Data Compression IC from ASAHI KASEI MICROSYSTEMS. This > chip provides a powerful data compression algorithm in a very small package. The data compression used by the chip is > the DCLZ algorithm. DCLZ has been standardized (or is in the process of standardization) with the ANSI, ECMA and > ISO standards organizations. The DDS Manufacturers Group (made up of representatives from active DDS Format > Licensees) has agreed upon the DCLZ algorithm as the standard data compression algorithm for data interchange be- > tween DDS format drives. > The DC control page allows the host computer to enable data compression and also configure the way in which the drive > responds to compressed/uncompressed data boundaries on the tape. > Note: The DDS format allows both compressed and uncompressed data to reside on the same tape. > SDT-10000/SDT-11000 has a Dip switch to disable the Data Compression. > After power-on reset with this jumper set, data compression is disabled. However, a MODE SELECT command can > override the setting of this jumper. > After power-on reset without this Dip switch set, both data compression and data decompression are enabled. (See > 3.1.5) > The more random the data is, the less compression is possible. This is due to the fact that data compression operates on > the principle of reducing the redundancy in the data string and random data has very little redundancy. > Data compression is a very powerful and reliable method increasing data capacity and transfer rate without compromis- > ing data reliability. > Compression Algorithm: > The compression algorithm field indicates the compression algorithm the drive will use to process data sent to it by > the initiator (if the DCE bit is one). > The SDT-10000/SDT-11000 supports the DCLZ data compression algorithm which is identified by the value: 00 00 > 00 20h in the compression algorithm field. A value of zero shall indicate that no compression algorithm is currently > selected. Any other values in this field will cause the drive to return a CHECK CONDITION status the sense key > shall be set to ILLEGAL REQUEST. > Decompression Algorithm: > For MODE SELECT the decompression algorithm field indicates the decompression algorithm selected by the > initiator for use in subsequent decompression of data encountered on the medium. > The SDT-10000/SDT-11000 can decompress data recorded with the DCLZ algorithm therefore this field can be set > to 00 00 00 20h. However, the SDT-10000/SDT-11000 is capable of automatic recognition of the compression > algorithm used to process the data encountered on the medium. Therefore, the drive will override the value in the > decompression field (if is set to zero) for a subsequent read operation when DCLZ compressed data is detected on > the media. > Note: A CHECK CONDITION will occur on the transition from uncompress to compressed if RED = 10b. > For the MODE SENSE command, the decompression algorithm field reflects either the algorithm selected > by the initiator or compression algorithm which was used to process the data most recently encountered on > the medium, during a read operation. > A value of zero shall indicate that the data encountered on the medium during the most recent read operation > was uncompressed.
I haven't found anything definite yet about DCLZ for the DAT40i. More about that later.
Matt wrote: > Scott Hemphill wrote: >> Matt <m...@themattfella.xxxyyz.com> writes:
>>> I was given two used SCSI DDS-4 tape drives, and I am testing them for >>> use in making backups.
>>> One is an HP DAT40i (aka C5686A, C5683A) and the other is a Compaq >>> SDT-10000 (EOD006, .
>>> I find that each drive can read the tapes that it writes, but that >>> neither drive can read the tapes written by the other.
>>> I have put a cleaning tape through each drive, and the firmware of >>> each drive is up-to-date. Both drives pass the diagnostics in the HP >>> Library & Tape Tool.
>>> Shouldn't these drives be able to read each other's tapes? Do I need >>> to adjust some parameters, or should I assume that at least one of >>> them is defective?
>> DDS-4 is DDS-4,
> I was guessing something like that. I think you are saying that the > format is as standardize as say ext3 or fat16.
>> but I'm not certain that they would use the same >> hardware compression technique, if you have that enabled via the >> jumpers on the drives.
> Thanks, Scott, I'll try that. So we are expecting/hoping to be able to > interchange any non-compressed DDS-4 tapes among DDS-4 drives.
> I found the following doc which gives a lot of technical detail on the > Compaq (rebadged Sony) drive.
>> Data Compression For Information Interchange >> Adaptive Coding with Embedded Dictionary, DCLZ Algorithm, June 1991 >> European Computer Manufacturers Association (ECMA-151)1
>> 4. 6 DATA COMPRESSION >> The tape capacity is increased by compressing data prior to writing it >> to the tape. Data compression is a well established >> technology for reducing the number of bits used to represent data in >> order to improve data transfer rate as well as reduce >> the amount of storage space consumed by the data. >> The SDT-10000/SDT-11000 uses the AK 8320 Data Compression IC from >> ASAHI KASEI MICROSYSTEMS. This >> chip provides a powerful data compression algorithm in a very small >> package. The data compression used by the chip is >> the DCLZ algorithm. DCLZ has been standardized (or is in the process >> of standardization) with the ANSI, ECMA and >> ISO standards organizations. The DDS Manufacturers Group (made up of >> representatives from active DDS Format >> Licensees) has agreed upon the DCLZ algorithm as the standard data >> compression algorithm for data interchange be- >> tween DDS format drives. >> The DC control page allows the host computer to enable data >> compression and also configure the way in which the drive >> responds to compressed/uncompressed data boundaries on the tape. >> Note: The DDS format allows both compressed and uncompressed data to >> reside on the same tape. >> SDT-10000/SDT-11000 has a Dip switch to disable the Data Compression. >> After power-on reset with this jumper set, data compression is >> disabled. However, a MODE SELECT command can >> override the setting of this jumper. >> After power-on reset without this Dip switch set, both data >> compression and data decompression are enabled. (See >> 3.1.5) >> The more random the data is, the less compression is possible. This is >> due to the fact that data compression operates on >> the principle of reducing the redundancy in the data string and random >> data has very little redundancy. >> Data compression is a very powerful and reliable method increasing >> data capacity and transfer rate without compromis- >> ing data reliability.
>> Compression Algorithm: >> The compression algorithm field indicates the compression algorithm >> the drive will use to process data sent to it by >> the initiator (if the DCE bit is one). >> The SDT-10000/SDT-11000 supports the DCLZ data compression >> algorithm which is identified by the value: 00 00 >> 00 20h in the compression algorithm field. A value of zero shall >> indicate that no compression algorithm is currently >> selected. Any other values in this field will cause the drive to >> return a CHECK CONDITION status the sense key >> shall be set to ILLEGAL REQUEST.
>> Decompression Algorithm: >> For MODE SELECT the decompression algorithm field indicates the >> decompression algorithm selected by the >> initiator for use in subsequent decompression of data encountered >> on the medium. >> The SDT-10000/SDT-11000 can decompress data recorded with the DCLZ >> algorithm therefore this field can be set >> to 00 00 00 20h. However, the SDT-10000/SDT-11000 is capable of >> automatic recognition of the compression >> algorithm used to process the data encountered on the medium. >> Therefore, the drive will override the value in the >> decompression field (if is set to zero) for a subsequent read >> operation when DCLZ compressed data is detected on >> the media.
>> Note: A CHECK CONDITION will occur on the transition from uncompress >> to compressed if RED = 10b. >> For the MODE SENSE command, the decompression algorithm field >> reflects either the algorithm selected >> by the initiator or compression algorithm which was used to >> process the data most recently encountered on >> the medium, during a read operation. >> A value of zero shall indicate that the data encountered on the >> medium during the most recent read operation >> was uncompressed.
> I haven't found anything definite yet about DCLZ for the DAT40i. More > about that later.
That's the culprit - HW compression chips differ in the compression algorithm used.
Set the drives jumpers to NOT use HW compression, then use software like the commercial BackupEdge (www.microlite.com) with software compression enabled, or pipe the backup through gzip or bzip2.
Pat Welch wrote: > Matt wrote: >> Scott Hemphill wrote: >>> Matt <m...@themattfella.xxxyyz.com> writes: >>>> One is an HP DAT40i (aka C5686A, C5683A) and the other is a Compaq >>>> SDT-10000 (EOD006, .
>>>> I find that each drive can read the tapes that it writes, but that >>>> neither drive can read the tapes written by the other. >>> DDS-4 is DDS-4, >>> but I'm not certain that they would use the same >>> hardware compression technique, if you have that enabled via the >>> jumpers on the drives. > That's the culprit - HW compression chips differ in the compression > algorithm used.
> Set the drives jumpers to NOT use HW compression,
Thank you, Pat.
I have docs for the Compaq drive describing how to do that, but I haven't been able to find good docs on the jumpers (DIP switches actually) for the HP DAT40i. Any specific information about that would be a big help.
Matt wrote: > Pat Welch wrote: >> Matt wrote: >>> Scott Hemphill wrote: >>>> Matt <m...@themattfella.xxxyyz.com> writes:
>>>>> One is an HP DAT40i (aka C5686A, C5683A) and the other is a Compaq >>>>> SDT-10000 (EOD006, .
>>>>> I find that each drive can read the tapes that it writes, but that >>>>> neither drive can read the tapes written by the other.
>>>> DDS-4 is DDS-4,
>>>> but I'm not certain that they would use the same >>>> hardware compression technique, if you have that enabled via the >>>> jumpers on the drives.
>> That's the culprit - HW compression chips differ in the compression >> algorithm used.
>> Set the drives jumpers to NOT use HW compression,
> Thank you, Pat.
> I have docs for the Compaq drive describing how to do that, but I > haven't been able to find good docs on the jumpers (DIP switches > actually) for the HP DAT40i. Any specific information about that would > be a big help.
See if this helps (took me a while to find it on HP's site):
Data compression - Switches 1 and 2 Switches 1 and 2 are used to configure the way in which data compression is set for the drive. The following table shows the available options:
Switch 1 Switch 2 Meaning On On Compression enabled at power-on, with host control
On Off Compression enabled at power-on, no host control
Off On Compression disabled at power-on; the host is allowed to control compression
Off Off Compression disabled at power-on, no host control
* If Switch 1 is ON, data written to the tape will be compressed without the knowledge of the host. * If Switch 2 is ON, data compression can be controlled by the operating system if supported. * By default, the drive will decompress data when reading a compressed tape, regardless of the settings of Switches 1 and 2. Decompression can be turned off through choice of device file, and can be controlled by the operating system if supported.
Bill wrote: > My bet is the HP is not compatible with anything else.
> "Matt" <m...@themattfella.xxxyyz.com> wrote in message > news:EFYXj.1378$ZB5.382@fe087.usenetserver.com... >> I'm testing using tar and diff for both. Also using the same SCSI adapter >> and the same computer for both. I test with only one tape drive installed >> at a time.
>> I test whether drive 1 can read the tape it has written, then I shut down, >> swap drives, and try to read the same tape with drive 2 and find that it >> can't read it.
>> Bill wrote: >>> Are you using the same software to test each?
