Re: Direct disk access on IBM Server

[David Brown <david@westcontrol.com>]

On 19/04/2011 16:07, Mathias Burén wrote:
> On 19 April 2011 15:04, David Brown<david@westcontrol.com>  wrote:
>> On 19/04/2011 15:25, Mathias Burén wrote:
>>>
>>> On 19 April 2011 14:21, David Brown<david@westcontrol.com>    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 follow‐
>                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".


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