fbackup

[Luis Varon]

Hy,

i have a question regarding fbackup and frestore.

A customer from us has an machine running hp-ux 11.00 with an tape device (dlt) installed.

If i scan for the hardware with ioscan -C tape -fun i get the following result:

Class I H/W Path Driver S/W State H/W Type Description
=====================================================================
tape 0 0/0/1/0.2.0 stape CLAIMED DEVICE BNCHMARKDLT1
/dev/rmt/0m /dev/rmt/c0t2d0BEST
/dev/rmt/0mb /dev/rmt/c0t2d0BESTb
/dev/rmt/0mn /dev/rmt/c0t2d0BESTn
/dev/rmt/0mnb /dev/rmt/c0t2d0BESTnb
tape 1 0/0/1/0.4.0 stape NO_HW DEVICE BNCHMARKDLT1

My Problem is that if i start a backup on /dev/rmt/0m with fbackup -f /dev/rmt/0m -i /tmp/backup_test i receive the following message:

fbackup(1004): session begins on Di., 17. Juni 2003, 17:09:51
fbackup(3205): WARNING: unable to read a volume header
fbackup(3024): writing volume 1 to the output file /dev/rmt/0m
fbackup(3055): total file blocks read for backup: 61
fbackup(3056): total blocks written to output file /dev/rmt/0m: 143
fbackup(1030): warnings encountered during backup

If i try to restore the files i must acknowledge many question (in the example i use -y) to restore the files:

frecover(2105): did not find expected file marker
frecover(5418): not an fbackup volume; unable to read volume header
frecover(2105): did not find expected file marker
frecover(5412): Do you wish to try to salvage this volume? (4304): automatic 'yes'
frecover(5413): attempting to read backup following bad volume header
frecover(1003): backup id does not match expected value
frecover(1061): attempt to continue recovery with new backup id? (4304): automatic 'yes'
frecover(1004): backup time does not match expected value
frecover(1062): attempt to continue recovery with new backup time? (4304): automatic 'yes'

My question in particular is: the file are obviously backed up and restored, but i would like to know if a backup could become unusable for recover and how can i verify or write a now volume header to the tape.

Many thanks in advance

Regards

Luis Varon

[David_246]

Hi Luis,

Please notice that you are using the not-rewind device. So therefor if you are reading back a backup you should do the "mt rewind"

If you never rewinded the tape this would be a logical error.
If not please let us know.

Regs David

[Massimo Bianchi]

Hi,
check these thread, they should answer most of your question.

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xe49f44f56197d711abdc0090277a778c,00.html

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x43a5e3ed7640d71190080090279cd0f9,00.html

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x7aa144f56197d711abdc0090277a778c,00.html

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x9a00595fae8bd711abdc0090277a778c,00.html

HTH,
Massimo

[Darren Prior]

Hi Luis,

The volume header is written to the tape the first time that fbackup writes to the tape. Hence the first time the tape is used by fbackup it won't be able to find the volume header. This is more of an informational message than a warning to worry about!

To save the volume header to a file so that you can inspect it you can use frecover -f /dev/rmt/0m -V filename

The volume header contains the number of times the tape has been used by fbackup, the time of the latest backup, etc - see man frecover for full details.

regards,

Darren.

[Michael Steele_2]

Use this command to verify your fbackup tape:

frecover -rNv -f /dev/rmt/0m | more

-or-

frecover -rNv -f /dev/rmt/0m > /tmp/file 2>&1

vi /tmp/file

To read volume header use:

/sbin/frecover -f /dev/rmt/???? -v -

[Luis Varon]

Hello,

first of all i want to thank every for answering and helping solving this problem.

I have tried to verify the header by using the commands you gave me and got an result.

First I want to say that i tried a second time to write on the tape but i received the same warning "WARNING: unable to read a volume header ".

The frecover brings me the following output when i want to verify the header:


Magic Field:
Machine Identification:
System Identification:
Release Identification:
Node Identification:
User Identification:
Record Size:0
Time:
Media Use:0
Volume Number:0
Checkpoint Frequency:0
Fast Search Mark Frequency:0
Index Size:
Backup Identification Tag:0 0
Language:

Tomorrow i want to verify if the tape has been written the first time with another tool than fbackup, maybe this is the problem why the header cannot be written or verified cleanly.

Many thanks.

regards

Luis

[Steven E. Protter]

I don't think you can verify the contents of an fbackup tape with another utility.

You can restore the file to another system. If its usable, thats the best you can do.

I recommend against relying on a tape with these errors on it.

I now segment the backup on my smaller tape systems so they fit on one tape.

Earlier, you thanked the other folks for solving your problem. It is customary in such circumstnaces to aware those people between 8-10 points.

Lastly: fbackup can not back up open databases like oracle. The only way and fbackup of an oracle database is useful in a supported way is if the database is down. Same thing for other databases.

I have gotten away with an fbackup restore of an open oracle database but was extemely lucky. The tape was made an hour after the database was brought up and there had been no transactions. This is called a fuzzy backup and IS NOT supported by Oracle. It was quite hard to recovery from this backup and oracle REFUSED to help me.

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