dmesg Error (PE-6850, RedHat 4 AS, EMC CX-300, QLA2340)

[Matias Oberti]

Florencio,
  Something important that you didn't explicitly say is if you're actually
seeing the LUN(s) you need besides getting that error or not. You just said
everything works fine, but....
  So, assuming that you see and use the LUN and that you have paths to both
SPs that behavior is normal. Why is it normal? because LUNs are presented to
hosts through only one SP at a time but it is possible that they need to be
failed over to the other SP in the event of a path or SP failure. So, the SP
that's not owning that LUN at that time will present a "LUN" which is not
real to the OS in order to reserve a "slot" for that LUN if it has to be
accessed by the other SP. As it's not a "real" LUN, by the time Linux tries
to get information of the LUN such as the partition table it will throw an
error saying it couldn't, which is ok.
  If you were using Windows and didn't have PowerPath installed yet a single
LUN would appear twice within the Disk Admin and one of them would be marked
as "unreadable" (that's the ghost LUN).
  In Linux, however, this "error" will not disappear when you install
PowerPath. Keep in mind that you'll have to use the /dev/emcpowera..b...c...
etc. devices in order to be using the PowerPath features.

  Now, if your host actually can't see you LUN(s). Check the pdf file within
the downloads section in the qlogic website to make sure you have everything
well configured. Or easier, call Dell TechSupport.

Regards and good luck.
Matias.


On 6/9/06, Ahmadz S. Taneo <ahmadz at amti.com.ph> wrote:
>
> Hi there;
>
> Good day!
> Am not sure but in my experience this error is cause when the CX300 fails
> to
> scan LUN 0. This can be fixed if you re-create your initrd image for multi
> LUN supports and your kernel parameter to enable "PROBE ALL LUNS"
>
> HTH
>
> ahmadz
>
> -----Original Message-----
> From: linux-poweredge-bounces at dell.com
> [mailto:linux-poweredge-bounces at dell.com]On Behalf Of Florencio Queiroz
> Sent: Friday, May 19, 2006 9:18 PM
> To: linux-poweredge at dell.com
> Subject: dmesg Error (PE-6850, RedHat 4 AS, EMC CX-300, QLA2340)
>
>
> Dear Sirs,
>
> I have an error at start-up of my server and CX-300.
>
> Hardware:
> Server: PE-6850
> Storage: EMC CX-300
> Fiber Controler: QLA2340
>
> Software:
> O.S.: RedHat 4 AS Update 3
> NaviAgentCli
> PowerPath 4.5.0
>
> Everything is working but the file dmesg shows an error.
>
> SCSI device sdc: 665156543 512-byte hdwr sectors (340560 MB)
> sdc: asking for cache data failed
> sdc: assuming drive cache: write through
> SCSI device sdc: 665156543 512-byte hdwr sectors (340560 MB)
> sdc: asking for cache data failed
> sdc: assuming drive cache: write through
> sdc:<6>Device sdc not ready.
> end_request: I/O error, dev sdc, sector 0
> Buffer I/O error on device sdc, logical block 0
> Buffer I/O error on device sdc, logical block 1
> Buffer I/O error on device sdc, logical block 2
> Buffer I/O error on device sdc, logical block 3
> Buffer I/O error on device sdc, logical block 4
> Buffer I/O error on device sdc, logical block 5
> Buffer I/O error on device sdc, logical block 6
> Buffer I/O error on device sdc, logical block 7
> Device sdc not ready.
>
> I think the error is occourring because the NaviAgentCli and PowerPath
> is not up yet, so the server doesn't reach the storage CX-300 and the
> device /dev/sdc is not ready yet.
>
> Is it true? Any advice?
>
> Thanks
>
> --
> Florencio Queiroz
> Coordenação de T.I.
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>
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