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remote tape to tape copy

David DaCosta
Occasional Visitor

remote tape to tape copy

Is it possible to copy a tape from one system to a tape on another system without writing to a disk? The systems areon a network and they are running tru64 5.1 and have dlt tape drives.
2 REPLIES
Ralf Puchner
Honored Contributor

Re: remote tape to tape copy

the commands

# rsh remotealpha '/sbin/vdump -0 -u -b 60 -f - /fileset' | dd of=/dev/nrmt0h bs=60k
# rsh dumphost 'dd if=/dev/nrmt0h bs=60k'|vrestore -x -v -f -

allows the remote usage of the tape devices. So modifying the command to use a local tape as input is easy.

But there is a huge performance impact leading to streaming mode (because the data will not be fast enough and tape stops/rewind/seeks the whole time, duplicating the backup time and stresses the tapes).

Using a professional backup tool and use cloning mechanism or remote storage devices is the right choice (e.g. networker).
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Volker Borowski
Honored Contributor

Re: remote tape to tape copy

Hello,

be sure what is on the tape and how it has been written.
You should use the same blocksize of the source tape to write the target tape.

Watch it if you have more than one fileset on the tape, you might need to use the no-rewind device on both ends and do several copy-runs in sequence, otherwise you might not get everything.

I.e. if the tape contains a SAP brbackup run writen with dd, you will have
tape-header, cpio-format 5120 Blocksize
config_A, cpio-format 5120 Blocksize
config_B, cpio-format 5120 Blocksize
datafile_1, dd-format blocksize as customized in initSID.sap
.... one set for each datafile
datafile_n, dd-format blocksize as customized in initSID.sap
logfiles-detail, cpio-format 5120 Blocksize
logfiles-summary, cpio-format 5120 Blocksize

So in this case, you might need n+4 copies with diffrent blocksizes to create a tape that is readable from brrestore.

... it depends on what's on it.

Hope this helps
Volker