How to verify a raw partition contains Oracle data - thanksGeofrey

Thu May 15 22:47:53 UTC 2008

Okay so you have multiple paths to a single partition, it sounds like
you
Need to setup multi-pathing, you only want to be dealing with a single
Device node file otherwise it's going to be very confusing for you.

Having said that, you said " I guess I have to use /dev/mapper/mpathx
in all references to avoid using duplicated paths", so I presume you're 
Presenting a total of 6 partitions to you OS, or is it 3?

Also, I'm not familiar with the /dev/mapper/mpathx construct - I'm guess
this the location that your HBA device driver places the device node
files
To refer to the partitions, do you know?

Regards,

Geofrey Rainey
Systems Engineer
D. 64 9 916 7178
M. 64 21 563 106
geofrey.rainey at tvnz.co.nz

-----Original Message-----
From: redhat-list-bounces at redhat.com
[mailto:redhat-list-bounces at redhat.com] On Behalf Of sunhux G
Sent: Thursday, 15 May 2008 9:48 p.m.
To: General Red Hat Linux discussion list
Subject: Re: How to verify a raw partition contains Oracle data -
thanksGeofrey

Hi Thomas,

We use Emulex.

Hi Geofrey

 "I don't quite understand what you mean when you say "/dev/sdv ...
fdisk
-l will not show them properly ...", or "/dev/mpath ...", presumably the
/dev/mpath/ directory is associated with the HBA driver and if so, you
might find the device node files within that directory refer to the
partitions
on the SAN"

Well, to elaborate, /dev/sdj & /dev/sdx may be two different device
files
but using different paths to get to the same disk partition on the SAN.
Somehow, after reboot, I found /dev/mapper/mpath[0-5]
- 6 of them altogether.

I guess I have to use /dev/mapper/mpathx  in all references to avoid
using duplicated paths to the same disk partition.  Did I make any
sense?

BTW, if I accidetanlly did "mkfs -t ext3 /dev/mapper/mpath0" but I
actually wanted it to remain as raw partition, how can I undo it so
that mpath0 is back to raw partition?

Thanks
U

On 5/15/08, Geofrey Rainey <Geofrey.Rainey at tvnz.co.nz> wrote:
>
> Hi,
>
> You can't see what's on a raw partition using standard file-system
tools
> such as "ls", because by definition a raw partition is "not cooked",
ie
> There is no file-system.
>
> The command "raw -qa" will only see raw partitions that have been
mapped
> To a raw device file in /dev/raw/, so that won't work either,
> furthermore
> The "raw" command only lists the raw devices, it doesn't see any data
> that
> Might be on those devices.
>
> Certainly the command "fdisk -l" will print out any partitions that
the
> System can see on any attached bus, if you don't see them then firstly
> I would try executing the "partprobe" command (which reloads the
> partition
> Table), then try "fdisk -l",  or reboot the box then try "fdisk -l".
If
> you
> Still don't see the SAN partitions, then there is something wrong with
> either the HBA (ensure you've got the driver sorted out), or the SAN
> config.
>
> I don't think one can easily see the data on a raw partition like one
> can
> On a file-system.
>
> I don't quite understand what you mean when you say "/dev/sdv ...
fdisk
> -l will not show them properly ...", or "/dev/mpath ...", presumably
the
> /dev/mpath/ directory is associated with the HBA driver and if so, you
> might
> Find the device node files within that directory refer to the
partitions
> on
> The SAN. In my experience with HBAs, vendor documentation is critical
> because their configuration can be quite arcane if it is all new to
> someone.
>
> Regards,
>
> Geofrey Rainey
> Systems Engineer
> D. 64 9 916 7178
> M. 64 21 563 106
> geofrey.rainey at tvnz.co.nz
>
>
>
>
> ---------------------------
>
> We have just presented quite a few SAN disk partitions to a couple of
of
> our Redhat servers.
>
> However, since the SAN is a shared resource, we need a way to verify
> that there's certainly no data in the raw SAN partitions, in
particular
> Oracle data/database.
>
> "/usr/bin/raw -qa "  returns nothing.
>
> Is there some sort of Oracle or tools that I can use?
> As it's raw partition, "ls /partiton_name"  won't help
>
> THanks
> U
>
>
> ----------------------------
>
>
>
> -----Original Message-----
> From: redhat-list-bounces at redhat.com
> [mailto:redhat-list-bounces at redhat.com] On Behalf Of sunhux G
> Sent: Wednesday, 14 May 2008 7:59 p.m.
> To: General Red Hat Linux discussion list
> Subject: Re: How to verify a raw partition contains Oracle data
>
> Just to add on a couple more questions :
>
>
> The SAN partitions are "/dev/sdh, /dev/sdv ... " & "fdisk -l"
> will not quite show them properly.
>
> Two other side questions :
> 1) A colleague who has left told me to let the DBA (an outsourced
>    vendor) to use /dev/mpath/mpath0   or  have I misquoted my
>    colleague
>
> 2) Do I need to reboot the Linux servers before the raw partitions
>    can be used?
>
> Thanks
> U
>
>
> >
> >
> >
> >
> >
> >
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