How to verify a tape backup?

QNX Newsgroups (Archives) qdn.public.qnx4
1

I am using pax to do a backup to tape on a Qnx 4 system. I can’t find
anything in the manuals that tells how to verify the data after the backup.
Can anyone give me some idea of how this is done, or direct me to the
information? I hate to do blind backups.

Thanks.

–

Joseph F. Muscarella
InfoSight Corporation

2

read the backup from the tape and use pax -v - if data intact should
list all the files

Padraig furlong

Joseph F. Muscarella wrote:

I am using pax to do a backup to tape on a Qnx 4 system. I can’t find
anything in the manuals that tells how to verify the data after the backup.
Can anyone give me some idea of how this is done, or direct me to the
information? I hate to do blind backups.

Thanks.

–

Joseph F. Muscarella
InfoSight Corporation

3

read the backup from the tape and use pax -v - if data intact should
list all the files

Thanks for the reply. How would I automate this as part of my backup
script? Also, I would want errors only to be reported, not all files.
This doesn’t necessarily indicate errors within individual files, does it?

Most tape backup software provides a verify feature to make sure that the
data written to tape is intact. This is what I am looking for. I don’t
think I asking too much since my data is important and I want confidence
that the backups are valid.

Thanks again,

Joseph F. Muscarella
InfoSight Corporation

4

Joseph F. Muscarella wrote:

read the backup from the tape and use pax -v - if data intact should
list all the files


Thanks for the reply. How would I automate this as part of my backup
script? Also, I would want errors only to be reported, not all files.
This doesn’t necessarily indicate errors within individual files, does it?

Are you using pax -w ‘files to be saved’ | vol -w ‘tape device’

if you are, then the reverse vol -r ‘tape device’ | pax -v will read
and check the data written to the tape. If it is successfull then the
archive is OK

Most tape backup software provides a verify feature to make sure that the
data written to tape is intact. This is what I am looking for. I don’t
think I asking too much since my data is important and I want confidence
that the backups are valid.

Thanks again,

Joseph F. Muscarella
InfoSight Corporation

5

We used to back up our systems with a scheme that used tee to hand the
output of pax -w to cksum and the tape. After writing all the files we
had one checksum for all the files. We then did a “tape bot” and
cat $tpdev | cksum.

In every case where an error ocurred, the simpler (and faster)
method similar to what Padraig describes would have also caught the
fact that the backup was bad or incomplete.

The cksum method required a fast cpu or a slow tape drive to maintain
a reasonable level of streaming. It also seems to cause Fsys.sym8scsi
failures with certain chipsets.

One other thing we do in our current script is to make certain the last
file written is read back.

Richard

Padraig Furlong wrote:

Joseph F. Muscarella wrote:

read the backup from the tape and use pax -v - if data intact
should
list all the files

Thanks for the reply. How would I automate this as part of my
backup
script? Also, I would want errors only to be reported, not all
files.
This doesn’t necessarily indicate errors within individual files,
does it?

Are you using pax -w ‘files to be saved’ | vol -w ‘tape device’

if you are, then the reverse vol -r ‘tape device’ | pax -v will read
and check the data written to the tape. If it is successfull then the
archive is OK

Most tape backup software provides a verify feature to make sure
that the
data written to tape is intact. This is what I am looking for. I
don’t
think I asking too much since my data is important and I want
confidence
that the backups are valid.
Thanks again,
Joseph F. Muscarella
InfoSight Corporation

6

“Padraig Furlong” <Padraig.Furlong@rte.ie> wrote in message
news:3D0846D9.9060204@rte.ie…

Are you using pax -w ‘files to be saved’ | vol -w ‘tape device’

if you are, then the reverse vol -r ‘tape device’ | pax -v will read and
check the data written to the tape. If it is successfull >then the archive

is OK

Here is the command line I am currently using:

pax -wv -b60b -x cpio -f /dev/tpr0 /dir1 /dir2 /dir3

I am not using vol, but I will investigate it’s use. Thanks for the idea.

Regards,

Joseph F. Muscarella
InfoSight Corporation

7

Thanks for the idea, although I think I will have speed issues because the
server is 6 years old and rather slow.

Regards,

Joseph F. Muscarella
InfoSight Corporation

8

To check your tapedrive backup the command would be
pax -v -b60b -x cpio -f /dev/tpr0

Padraig

Joseph F. Muscarella wrote:

“Padraig Furlong” <> Padraig.Furlong@rte.ie> > wrote in message
news:> 3D0846D9.9060204@rte.ie> …

Are you using pax -w ‘files to be saved’ | vol -w ‘tape device’

if you are, then the reverse vol -r ‘tape device’ | pax -v will read and

check the data written to the tape. If it is successfull >then the archive
is OK

Here is the command line I am currently using:

pax -wv -b60b -x cpio -f /dev/tpr0 /dir1 /dir2 /dir3

I am not using vol, but I will investigate it’s use. Thanks for the idea.

Regards,

Joseph F. Muscarella
InfoSight Corporation