[CentOS] Poor RAID performance new Xeon server?

[John R Pierce]

Stewart Williams wrote:
> John R Pierce wrote:
>   
>> Stewart Williams wrote:
>>     
>>> The block I/O is the thing that concerns me as mostly I am serving a 
>>> 650MB file via samba to 5 clients and I think this is where I need the 
>>> speed.
>>>       
>> is this a sequential or random access application thats using this 
>> file?   is it read only/mostly, or is it random update?
>>     
>
> I'm not sure, how can I find this out?
>   

well, what is the nature of the application thats using this file?     
do you really mean just a single 650MB (sub 1GB) file?
is this something like a quickbooks file? (thats kind of what it sounds 
like from your other answers).

given what you have now, and what information we've been given, I would

    A) disable BIOS raid, configuring it for JBOD w/ ACHI enabled
    B) mdadm mirror disks 0 and 1, and put the OS on that
    C) mdadm mirror disks 2 and 3, and put your shared SMB filesystem on 
that