Re: Export/Import to tape?

In article 726774727_at_unixg.ubc.ca, bogreen_at_unixg.ubc.ca (Bo Green) writes:
>
> 1) I need to change the tablespace allocation of a large database I am
> working with, so I thought the best way would be to Export, create
> new tablespaces, and then Import the tables. Unfortunately, I don't
> have enough disk space to Export to disk. I figure out how I can Export
> to exabyte tape in a reasonably efficient way. Any ideas?
>>
> Bo Green
> Centre for Health Services
> University of BC
> Vancouver, Canada

---
With Ver 6 I have (with some fiddling) been able to accomplish direct
compressed exports(imports) to tape or disk by using named pipes to
filter the output(input) through unix "compress".  I have achieved
80-90% compression with this method and have not had to use temporary
files since compression is done "on-the-fly".

Essentially, for the export process, I create a named pipe to write
to.  "Export" thinks its a file and will write to it.  In the
background I have a process running  which takes its input from the
named pipe, runs it through "compress" and "dd" and writes to the
tape.  I.e. start

  compress < {namedpipe} | dd obs=5120 of={tapedevice} 2>/dev/null &

and then do export to the named pipe.

Similarly for import, only in reverse.

It's not quite this simple but it does work.  I have a script to deal
with it.

Since the compression is so great it would be nice if export and an
option to do this internally.

___________________________________________________________________________

Jeff.Stander_at_ml.csiro.au        _--_|\        Database Analyst
CISRO Division Of Fisheries    /      \       Pelagic Fisheries Resources
GPO Box 1538, Hobart           \_.--._/       Tasmania 7001, Australia
Aus Tel: 002-206-206                 v        Intl Tel: +61-02-206-206
Aus Fax: 002-240-530                          Intl Fax: +61-02-240-530
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