Tar Problem

[sumedha_1]

Hello,

I have a two fold question.

1) Recently i gave the command
# tar -cv /home
as the size of data was beyond the capacity of the tape , when it came to end of tape it prompted me to insert another tape to continues , where i have pressed enter to come back to the promt ie #.

After this i am not able to do do a tar even with the option of
#tar -cvf test.tar /tmp.

This throws an error theat /tmp/****/sdfsdf is not a file not dumped.

and the option of backing on to the tape too gives a following error
# tar -cv /home
tar: cannot open /dev/rmt/0m
#

I am not able to take backup;s using SAM too after this event.


2) I know my Tape drive supports compression but how do i force my tape with tar to tar usign Compression to save space on my tape and complete the operation using a single tape.

Regards
Sumedha

[Stefan Farrelly · Accepted solution]

Firstly you have a problem with your tape drive. It needs resetting. Try removing the tape and inserting it again, then try a simply test to see if its working;

dd if=/dev/rmt/0m of=/dev/null count=10

Does it come back with 0+0 records in, 0+0 records out ? IF so good, this means your drive is now working. If not you may need to reset the power to your tape drive, if its internal you may need to reboot your server to get it working again.

As for compression (hardware), by default it is on for DDS drives. If you do the command> lssf /dev/rmt/0m
and it comes back with "...best density..." then it has hardware compression already on.

To try to fit your backup on tape try using fbackup, it blocks better and you may be able to squeeze more onto one tape, and it handles asking for a second tape aok. Or use tar and pipe it into dd before it goes to tape, this way you can use a large blocking factor and again try to squeeze more onto a single tape, eg; tar cvf - /home | dd of=/dev/rmt/0m bs=64k

How big is your tape drive ? (what does ioscan -fknCtape show) and what size tapes are you using (60/90/120/125m) ? and how much data are you trying to fit on it ? (du -sk )

[Animesh Chakraborty]

Hi,
when you spcify cvf you have to mention the device file /dev/rmt/0m.
chack the followings:
#ioscan -fnC tape
see the device file is there at /dev/rmt/0m.
#lssf /dev/rmt/0m


Thanks
Animesh

[Robin Wakefield]

Hi Sumedha,

Are you saying you have something on your system called "/tmp/*****/sdfsdf ? If so, I would see what it is and remove it if possible.
The error "not a file:not dumped" normally relates to tar encountering a socket file, or some other non-standard file.

Check if there is a tar session still running, & check if the tape device is in use:

ps -elf|grep tar
fuser /dev/rmt/0m
lsof /dev/rmt/0m (if you have lsof)

Also, check the output of:

lssf /dev/rmt/0m

this should tell you if the device file is already running at best density.

Rgds, Robin.

[Paula J Frazer-Campbell]

Hi

It appears your tar command failed on the tape change and it still has the device file open - hence you cannot connect to it.

Do a ps -ef | grep tar and pick up and kill the ps.

An option on you backup with tar is to gzip the data first and then tar it off.

Paula

[sumedha_1]

Hi,

Thanks a lot for the inputs.

Let me asnwer one by one,

Stefan;
Thanks again, your inputs were valuable .these were something i did not know.
Compression is already enabled.
Its external device, reseting did not help and i had to reboot the workstation.
When it was online again i gave tar -cvf /opt/CCCX and after some 40 mins of backup it gave this

Tar: to continue, enter device/file name when ready or null string to quit.

When i repolaced another tape to continues from where tar had stopped it did not contined , but dd worked.



Animesh,
Thanks again for your inputs. But i think its not necessary to mention "f" with cv if i am backingup on tape as the default is /dev/rmt/0m. Correct if i am wrong.

Robin,
I do not have lsof on HPUX but fuser did not throw any outfut for the device.
Thanks again for your inputs.

Paula,
Actually i had tried that before posting to the group but again that did not throw any outputs.


People,
I have found that restat does correct the problem , but i am sure that you will agree with me that restart is not the solution.

After the restart i ahve landed into the same problem.Now i cannot restart this machine twice in one day, leave alone a week/month.

Stefan , I would like to try the option you gave me of forcing more data on the tape but now i am not able to run tar on that device.

Can you people see an other solution.

Waiting for a response.

Sumedha

[sumedha_1]

Stefan,

Did not mention the output of ioscan.

# ioscan -fknCtape
Class I H/W Path Driver S/W State H/W Type Description
=====================================================================
tape 0 8/16/5.3.0 stape CLAIMED DEVICE HP C1533A
/dev/rmt/0m /dev/rmt/c1t3d0BEST
/dev/rmt/0mb /dev/rmt/c1t3d0BESTb
/dev/rmt/0mn /dev/rmt/c1t3d0BESTn
/dev/rmt/0mnb /dev/rmt/c1t3d0BESTnb

Hope this helps
Sumedha

[Stefan Farrelly]

If youre at the point now where you cant do a rewind (mt -t /dev/rmt/0m rew) without an error, or echo > /dev/rmt/0m then you have to reboot again.

Tar doesnt handle multiple tapes well, dont use it. Use fbackup instead - its much much better and handles multiple tapes.

You have a C1533A - DDS2, which with a 120 metre tape in can handle up to 8 GB with 2:1 compression (4 GB uncompressed). How much data are you trying to backup to it?

[sumedha_1]

Hi,

Its a 4/8 GB DDS2 Tapes on a HP SureStore Drive and on an average i backup arounf 3-5GB of data.

Waiting for your inputs.
Sumedha