Re: Direct disk access on IBM Server

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On 19/04/2011 17:41, Mathias BurÃn wrote:
On 19 April 2011 16:12, David Brown<david@xxxxxxxxxxxxxxx>  wrote:
On 19/04/2011 16:07, Mathias BurÃn wrote:

On 19 April 2011 15:04, David Brown<david@xxxxxxxxxxxxxxx>    wrote:

On 19/04/2011 15:25, Mathias BurÃn wrote:

On 19 April 2011 14:21, David Brown<david@xxxxxxxxxxxxxxx>      wrote:

I have recently got an IBM x3650 M3 server, which has a "Serveraid
M5014"
raid controller.  Booting from a Linux CD (system rescue CD) and
running
lspci identifies this raid controller as:

LSI Logic/Symbus Logic Megaraid SAS 2108 [Liberator] (rev 03)

The controller works fine for hardware raid - I can open its bios setup
utility, and set up a RAID5 (or whatever) with the disks I have.  The
OS
then just sees a single virtual disk.

But I would like direct access to the sata drives - I want to set up
mdadm
raid, under my own control.  As far as I can see, there is no way to
put
this controller into "JBOD" or "direct access" mode of any sort.

Does anyone here have experience with this card, or can give me any
hints?

The only idea I have at the moment is to put each disk within its own
single-disk RAID 0 set, but then I don't get sata hot-swap
functionality,
SMART, hddtemp, etc.

Thanks for any clues or hints,

David


Regarding SMART, could you try (after loading the appropriate
megaraid/megasas module) hdparm -a -d megaraid,$I /dev/sda , where $I
is a number between 0 and 31 IIRC (depending on the HDD in the array).


Are you sure about the syntax for that command?  Trying that with "0" for
$I
just gives me "megaraid,0: No such file or directory".  As far as I can
see,
the megaraid module is loaded (lsmod shows "megaraid_sas" in the modules
list).

Thanks anyway,

David



  From the smartctl man page:

          Under Linux , to look at SCSI/SAS disks behind LSI MegaRAID
controllers, use syntax such as:
               smartctl -a -d megaraid,2 /dev/sda
               smartctl -a -d megaraid,0 /dev/sdb
               where  in the argument megaraid,N, the integer N is the
physical disk number within the MegaRAID controller.  This interface
will also work for Dell PERC controllers.  The followâ
               ing /dev/XXX entry must exist:
               For PERC2/3/4 controllers: /dev/megadev0
               For PERC5/6 controllers: /dev/megaraid_sas_ioctl_node

Maybe you can experiment some with that. Regards,
M

Ah, it was "smartctl" - you first wrote "hdparm".  I should have thought of
smartctl myself.

Still no luck as yet - the smartctl on my test installation (Centos 5.6)
doesn't seem to support megaraid devices.  But maybe that's just because it
is an older version of smartctl - Centos 5.6 is not exactly "bleeding edge".


Opps, sorry! I blame the medicine. You could try compile a version of
smartctl yourself if you have the proper packages installed.


The CentOs installation is only temporary. I was doing some testing with IBM's software, which will only work on certain very specific Linux versions, such as various RHEL versions. Since I like to use Debian on servers (it's what I'm used to), I didn't fancy buying RHEL just to try out the software - CentOS was a simple and convenient way to test the software. Once I get my "real" installation in place, I can make sure I have up-to-date tools.

Thanks for your help and pointers,

David

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