Re: File Systems vs. Raw Devices

In article <12a.2266.905.0N3E1F88_at_compudata.com>

           barry.roomberg_at_compudata.com "Barry Roomberg" writes:

> -> Raw devices are a complete bitch to recover as well. 'dd' rules the
> -> roost here. If you're planning on shunting databases from machine to
> -> machine they're not a wise idea.
>
> Com'n. I DD across networked machines to copy databases constantly.
> No problems, and great performance.

Gick. I have *never* managed this one perfectly. We used to use 'hot' backups which dd'd stuff onto tape, but problems I had with moving databases was that the control files sometimes didn't let you open your database back up since the DataDictionary's idea of where the files were had to be reassigned via ALTER DATABASE RENAME DATAFILE ... ( or whatever... )

> -> If you're planning to use raw devices on a disk, partition a must be
> -> 1 block in size only. ORACLE needs this. I learned this from bitter
> -> experience.....
>
> Please explain. "1 block in size only" ??? Huh?

Well, in your partition table on each disk with a raw device being used, if partition 'a' isn't at least one block in size, when you begin to create tablespaces on your raw partitions, the disk's partition table resets itself to its previous/default setting......Strange, but true! The solution is to create partition 'a' as being one block in size.

This is on SunOs 4.1.3 SPARC platform, incidentally.....I can't speak of raw devices on other platforms.....

Hope this clears up my previous statement...

-- 
Alligator Descartes
v_at_istellar.demon.co.uk