make_recovery

[jerry1]

What is the drive/tape capacity of a DDS 1?

DDS 1: ? --2GB?
DDS 2: 4GB
DDS 3: 12GB
DDS 4: 20GB

When I do a make_recovery -Av. I get the
infumus error message:

make_recovery(472): /usr/bin/dd failed,res=512,errno=0

HP-UX 10.20. 4 boxes all started failing
around the same time. I can only assume
that the make_recovery cannot put all the
data on tape.

I can do a diskinfo /dev/rmt/0m
It indicates 2GB.

# diskinfo /dev/rmt/0m
SCSI describe of /dev/rmt/0m:
vendor: HP
product id: HP35480A
type: sequential access
size: 2103247 Kbytes
bytes per sector: 1024


Tape is a DDS 1 tape.
The ignite file is 28 Meg:

28240896 uxinstlf.recovery

[TTr]

It looks like you get the "dd" error during the creation of the bootfile, which means you may be running out of space on the filesystem that the bootfile is created temporarily. Check with bdf and see if /tmp or /var are low on available space.

[jerry1]

Checked space. Plenty.

[Torsten.]

For capacity see

http://en.wikipedia.org/wiki/Digital_Data_Storage#DDS-1

[Steven E. Protter]

Shalom,

Do not assume.

Read the Ignite logs under /var/opt/ignite

2 GB is a significant number. Its the largest file size permitted on a file system unless largefiles is enabled.

DDS2 can handle 8 GB of data
DDS3 Can hanlde 24 GB of data

Both figures are optimistic figures including near perfect compression.

SEP

[Patrick Wallek]

>>Both figures are optimistic figures
>>including near perfect compression.

COMPRESSED tape capacities are always figured with a 2:1 compression ratio, basically compressed to 1/2 its original size. Sometimes you can get better, sometimes not.

The capacities you cite are the correct NATIVE (non-compressed) capacities for those generations of DDS tapes.

Here is a good reference for DDS capacities and speeds:
http://www.supermediastore.com/dds-faq.html

[TTr]

I think the "dd" command is used by make_recovery to put the bootfile on the tape first. After that it changes over to "tar" for the file archive. So the dd error is probably an indication of a problem on the tape drive side. Check for bad tape, clean drive, bad drive, cables etc.

[Bill Hassell]

DDS-1 is really, really old and was the first data standard based on the DAT (Digital Audio Tape). The 60 meter tape was the same form factor as DAT tapes and they were often used interchangeably with poor results. This similarity gave DDS drives and media a bad name because the allowable error rate for DAT tapes was very high, something that was OK for audio (not usually audible) but quite unacceptable for data. DDS1 tape drives have *no* compression capability so for a 60 meter tape, you might get about 1200 MB, or 2000 MB for a 90 meter tape.

Now this format is extremely old (archaic) in computer years so your tapes may also be very old. And tapes do not age well. Sony and HP designed the DDS format in 1989, some 20 years ago. DDS tapes were designed with about a 10 year lifetime.

So are your DDS (not DAT) tapes less than 10 years old? Test your tapes with a simple program like tar:

tar cvf /dev/rmt/0m

If that fails, try different tapes (but only those compatible with your drive). If nothing works, your drive is defective. Good luck finding another DDS1 drive. Be sure to check this compatibility document from HP:

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=lpg50457&locale=en_US&taskId=101&prodSeriesId=81997&prodTypeId=12169

[jerry1]

I will try the tar to verify.
I have noticed that sometimes, 1 out of 10 tries, on one box, it will succeed.

Two drives are bad on two boxes and we
are replacing them with DDS2. They were
hard to find also.