Re: The old raw devices chestnut.

From: Mark Bole <makbo_at_pacbell.net>
Date: Wed, 14 Apr 2004 04:15:33 GMT
Message-ID: <FV2fc.36686$v_1.29889@newssvr29.news.prodigy.com>

Andrew Hamm wrote:

> Mark Bole wrote:
>

>>I haven't worked with an Oracle raw device since version 7.3 seven
>>years ago, and would never go back.  The administrative overhead is
>>just too much of a headache.

>
>
> [Posting from comp.databases.informix]
>
> I've never understood the "administrative overhead" argument against raw
> spaces. Can you elicidate on the administration you think needs to be
> applied? In my experience, the only admin overhead is making sure that a
> new, naive sysop doesn't try to turn a raw space into a filesystem - I saved
> an engine by SECONDS once, by looking over the shoulder of said sysop as I
> walked past....
>
> Apart from that, I find that admin is slightly simpler simply because you
> don't need to run a mkfs style of command ;-)
>
> I have heard that Solaris (?) is in the habit of re-creating /dev at boot
> time, and I know that DG-UX used to do the same thing. Therefore some sort
> of tool is needed to make sure the raw devs exist after a boot. Is this what
> you mean?
>
>

Gawd, this cross-posting is a little scary... I've touched DB2, administered Sybase for four years in the mid-nineties, otherwise Oracle is it... so take the following for whatever it's worth.

To answer the question above: no, actually my experiences with Oracle raw devices were under DEC Ultrix, SGI Irix, and HP-UX. I've only managed "normal" filesystems under Solaris, Linux, and Windows. To this day the thought of messing with the /dev filesystem stresses me out... --)

Yes, I've had to recover production (Oracle, Sybase) systems in real life disaster situations: Score: raw filesystems, W-1, L-1. cooked filesystems, W-2, L-0. So you can see where I'm heading...

I use "adminstration" in a very tool-oriented sense. With cooked file systems (which I am defining as filesystems the OS is designed for... tautology or no...), there are lots of tools: tools for timestamps, tools for sizes, tools for checksums, tools for copying, tools for finding, tools for checking open handles, and so on. With raw filesystems, I have none of these tools. (OK, wrong if you consider "dd" under Unix to be a tool....)

Your own example serves to make my point: the set of admins, naive or otherwise, who stand a chance of disaster recovery with raw filesystems in the 21st century is an order of magnitude less than those who stand a chance of disaster recovery with "normal" filesystems.

And just to put the skin on the pudding, isn't the stated direction of MSFT to turn the entire filesystem into a database? Whither raw partitions then?

--Mark Bole Received on Tue Apr 13 2004 - 23:15:33 CDT