Re: Backup to NFS

From: Mladen Gogala <mgogala.SPAM_ME.NOT_at_verizon.net>
Date: Wed, 09 May 2007 06:10:12 GMT
Message-ID: <pan.2007.05.09.06.10.12@verizon.net>

On Tue, 08 May 2007 08:30:36 -0700, DA Morgan wrote:

> An important consideration I should have mentioned before. RMAN and a
> temporary NFS mount such as:
>
> # mount -t nfs 192.168.20.160:/vol/stage /mnt
>
> will not work: Mount using FSTAB.

Well, I believe that options are more important then the technique itself. Configuration files like /etc/fstab are also parsed and, eventually, handed to a program that calls "mount" system service - see mount(2) or even the CLI version of the mount. During the startup Unix systems do a horrible patchwork of grepping through /etc/fstab, /etc/hosts and other configuration files. Newer versions of Linux even have Mother's little helper like this:

[root_at_medo ~]# which fstab-decode
/sbin/fstab-decode
[root_at_medo ~]#
[root_at_medo ~]# file /sbin/fstab-decode
/sbin/fstab-decode: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.9, stripped
[root_at_medo ~]#
[root_at_medo ~]# man fstab-decode

fstab-decode(8)                                                fstab-

decode(8)

NAME
       fstab-decode - run a command with fstab-encoded arguments

SYNOPSIS
        fstab-decode COMMAND [ARGUMENT]...

DESCRIPTION
       fstab-decode decodes escapes in the specified ARGUMENTs and uses them

       to run COMMAND. The argument escaping uses the same rules as path

       escaping in /etc/fstab, /etc/mtab and /proc/mtab.

EXIT STATUS
       fstab-decode exits with status 127 if COMMAND can’t be run. Otherwise

       it exits with the status returned by COMMAND.

EXAMPLES
       fstab-decode umount $(awk ’$3 == vfat { print $2 }’ /etc/fstab)

This program is clearly intended for being used within the sysinit script. My only gripe is that nobody thought of using Perl for that purpose. The only thing missing in /etc/init.d/rc.sysyinit is Perl. In other words, the effect of writing a monstrous command line like:

mount -t nfs -o
rw,bg,hard,nointr,rsize=32768,wsize=32768,tcp,vers=3,timeo=600 lap:/ export/fs /mnt

and putting it in /etc/fstab will be exactly the same, as far as oracle is concerned.

-- 
http://www.mladen-gogala.com

Received on Wed May 09 2007 - 01:10:12 CDT