the error message from fbackup

[peterchu]

I use fbackup to backup the file to the DDS tape , it work fine , but today it pop the error "WARNING: unable to read a volume header" , however I can restore all the files from the tape , could suggest what is the error mean ? thx.

[Murat SULUHAN · Accepted solution]

Hi peterchu

Check this doc

http://www4.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&admit=-938907319+1094806340197+28353475&docId=200000062965761


Best Regards
Murat

[Sridhar Bhaskarla]

Hi,

fbackup keeps track of the usage of the tape by writing/updating volume headers to it whenever a tape is used by it.

When a new tape (or non fbackup tape) is used, fbackup will not find any header information on it hence it will print the information.

-Sri

PS: This is perhaps 5th time I am posting this response in this thread. Have been getting "Connection timeout" errors.

[john korterman]

Hi,

fbackup checks if the tape has a fbackup header.
A new tape of course has not, hence the message, which probably has scared a lot of people - dont't worry, you will see it every time you use a new tape.

regards,
John K.

[peterchu]

thx reply ,

but this is not a new tape , I used this tape for many many times , and the tape should have a old backup inside , my backup script will format the tape before start to backup , is it normal ? thx

[Sยภเl Kย๓คг]

This is due a bad tape only.Just track the usage of tape .Recommend you use a new tape at present.
regards
SK

[Darren Prior]

How is your backup script formatting the tape before the backup? If it overwrites fbackup's header (which is how it knows how many times the tape has been used) then it will think the tape is new.

regards,

Darren.

PS: Please don't forget to assign points to those that have given up their time to assist you. It also helps others find good answers when searching the forums.

[Sridhar Bhaskarla]

yep.. If you do a mediainit on it, then the headers will be gone.. So, this is perfectly normal.. But I wouldn't suggest you format it if you are going to use it with fbackup. Tapes are not that costly but the data is. So, after 'n' number of attempts as displayed by fbackup, recycle the tapes to ensure the backup integrity.

-Sri

[peterchu]

this problem sometimes happen, I use the same backup script from long time ago , the script will not erase the volume header of the tape , is it the tape was damage then the drive can't read something from it ?

[peterchu]

what is the use of this header , is it the fbackup write something to the tape when every time to start backup ? thx.

[Darren Prior]

take a look at the man page for frecover, the contents of the header is discussed under the -V option.

[john korterman]

Hi,

an important use of the fbackup header is for instance to keep track of the number of times the tape has been used.

regards,
John K.

[peterchu]

thx replis,
in my case , is it my header is full or in a critical level becuase I hv already use it for too many times,

I hv two more questions:

1. if I can restore the header , can I know how many times I hv use the tape ?

2. to prevent the warning , can I erase the existing header information , so that the warning will not shown again .

thx

[john korterman]

Hi,
1) I do not think that you can restore the header; if the header has been erased I assume a new one will start counting from zero. But it is quite easy to check, e.g. by frecover -V, e.g.:
# frecover -V /tmp/fbheader

# more more /tmp/fbheader
Magic Field:FBACKUP_LABEL
Machine Identification:9000/897
System Identification:HP-UX
Release Identification:B.10.20
Node Identification:kmdstst
User Identification:root
Record Size:32768
Time:Sat Sep 11 10:14:21 2004
Media Use:5
Volume Number:1
Checkpoint Frequency:32
Fast Search Mark Frequency:200
Index Size:1750
Backup Identification Tag:15148 1094890461
Language:
fbheader: END

2) I do not think that you can avoid the warning originating from a new tape, but perhaps others have a way of doing that.

regards,
John K.

[Bill Hassell]

The fbackup header is just the first record written on the tape. If the tape is left unprotected (write tab is left enabled, tape is not put away is a safe place), anyone can pop in the tape, run tar, cpio, dd, dump, pax or simply cat a file to the tape and the fbackup header is gone. If the loss of the header is unexpected, your script should trap this condition by first reding the header with:

MYTAPE=/dev/rmt/whatever
MYLABEL=$(frecover -V - -f $MYTAPE)
if [ ${#MYLABEL} -eq 0 ]
then
echo "tape has no fbackup header"
exit
fi

Naturally this script should send email or otherwise notify you of the problem. Then you can examine the tape to what was written on the tape. Start with the file command:

dd if=/dev/rmt/0m > xx
file xx

file will 'guess' at the taoe format with a table of magic numbers (man file). If file knows the format, you can use the appropriate utility to see what was written to the tape, which in turn might tell you who used the tape inappropriately. file cannot identify random use like a cat command so just cat the xx file to see if you can see something you recognize:

xd -xc xx