Disk mapping for oracle ASM (Matty Sarro)

[Geofrey Rainey]

Using the device node file names such as /dev/sda isn't encouraged
because the device mappings may not persist across reboots. For
instance, /dev/sda might be enumerated to /dev/sdb upon reboot then
you're in all kinds of trouble and this why one must setup multi-pathing
and reference the device names as /dev/mapper/<device>.

-----Original Message-----
From: redhat-list-bounces at redhat.com
[mailto:redhat-list-bounces at redhat.com] On Behalf Of raj sourabh
Sent: Tuesday, 7 December 2010 5:04 p.m.
To: General Red Hat Linux discussion list
Subject: Re: Disk mapping for oracle ASM (Matty Sarro)

Hi Matt,

Correct.. Its better to check it whether oracleasm service affects the
DB
:)  However in all my current deployments I have used raw devices ..

I have another doubt in this regard(may sound silly).. but Why can't the
direct devices (soft links .. eg /dev/sdc, /dev/sdd) could be used for
asm
disks..????

Regards,

Raj



On Mon, Dec 6, 2010 at 8:07 PM, Matty Sarro <msarro at gmail.com> wrote:

> Please correct me if I am wrong, but I think you may be confusing the
the
> kernel library used to access the disks and the separate utilities
used to
> manage/configure the disks. They're separate things :) The management
> utility marks the disks to be read/written to by the library, so it
can die
> and you should still have no problem accessing your data. Sort of like
> fdisk
> could die, but you'd still be able to access your SATA and IDE drives
> without any problem. It'd be easy to play with if you have a few
minutes;
> just kill the ASM service and see if your db dies or not :) I think
you'll
> be pleasantly surprised. Again, this is just with my cursory knowledge
of
> ASM so I could be wrong.
> -Matty
>
>
> On Mon, Dec 6, 2010 at 1:45 AM, raj sourabh <rajsourabh1 at gmail.com>
wrote:
>
> > Hi,
> >
> > Thanks for the information.
> >
> > But dont you think if oracleasm deamon/service is hung or stoppedon
> > nodes then your whole database comes down. This was't the case with
raw
> > devices. Even though there is entry for it in /etc/init.d/rawdevices
but
> in
> > RHEL 5.5 you can not stop or start it :)
> >
> > Regards,
> >
> > Raj
> >
> > On Mon, Dec 6, 2010 at 6:35 AM, Yong Huang <yong321 at yahoo.com>
wrote:
> >
> > > Regarding kernel upgrade and ASMlib upgrade, there may be an
annoyance
> > > to some people finding the correct ASMlib on Oracle OTN web site.
It's
> > > better to always go to
> > >
>
www.oracle.com/technetwork/topics/linux/index-101839.html#oracleasm_2_0
> > > instead of search at otn.oracle.com. The search result may list
> multiple
> > > pages that appear to have the libraries. But the first link points
to
> > > a page that may be missing the libraries while the page I showed
above
> > > has it.
> > >
> > > Once you installed with rpm, do:
> > > /etc/init.d/oracleasm enable
> > >
> > > ASM is the future. Raw is deprecated.
> > >
> > > Yong Huang
> > >
> > >
> > >
> > >
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