RE: AIX raw device offset
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <jheinrichdba@xxxxxxxxx>, "'oracle-l'" <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 10 Jul 2008 17:55:59 -0400
dd from an existing raw volume to a regular file on a JFS volume for a file
system you don't care about (possibly created for the purpose). Then od the
file and look for the offset where you see a typical Oracle file header. I'm
pretty sure Oracle's files are 1 database block size bigger than you asked
for as well, so make sure you have at least offset plus file size you think
you have plus 1 db block size available on the raw device you prepare to
receive the new file. (That's for it to work at all. Getting the header
aligned in a good way compared to the underlying physical storage that is
being presented by the volume manager to the OS is another matter.)
I won't even pry into why you're still using 7.3.x.
By the way, unless this is an nth file of a multi file tablespace or a huge
tablespace, I'd think seriously about creating a new tablespace the way you
want it, copying the data you want to keep, and then dropping the old
tablespace including contents. If it is a big tablespace that is probably a
lot of i/o, but if you've got the space to do it it will be a lot safer.
Even the dinosaurs who used to do this stuff frequently are rusty at doing
it by now, and if I recall correctly some OS documents were at a lower
standard of exactness than the general Oracle documentation.
Regards,
mwf
_____
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Jason Heinrich
Sent: Thursday, July 10, 2008 3:13 PM
To: oracle-l
Subject: AIX raw device offset
Oracle 7.3.3
Oracle Parallel Server
A coworker of mine needs to move a datafile that was accidentally created on
a local JFS volume to a shared raw device. He's planning on using dd. Can
anyone tell me what the correct offset is for the start of the datafile on
an AIX raw device? It's my understanding that AIX writes its own info to
the first x bytes of the device, so the Oracle file header needs to start
after that.
Sorry, I don't know what version of AIX this is offhand. If that matters,
let me know and I'll try to find out.
--
Jason Heinrich
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