Hardware RAID or software for ZFS

[Warren Block]

On Tue, 18 Nov 2014, Matthew Seaman wrote:

> On 11/18/14 15:28, bsd at todoo.biz wrote:
>> I would need your help in order to figure out which will be the best in order to setup a server which will be used as a Poudriere server.
>>
>> My question is related to the usage of hardware RAID controller (JBOD) or software based controller (graid)
>>
>> Server we are targeting is a SuperMicro 1018R-WC0R - 1U
>>
>> I used to build my server using an HBA such as LSI SAS 9207-8i or LSI SAS 9201-16i
>> Then I?ll configure the HBA as JBOD so that disks can be presented correctly to the system so that we can build our ZFS FS on top of that.
>>
>>
>> My sysadmin suggested me to get rid of the HBA and use direct connectivity and Graid.
>>
>>
>> I would like to have some feedback on various aspects :
>>
>> 1. performance
>> 2. usability
>> 3. problem one might have encountered
>>
>
> OK -- Your sysadmin is correct about the direct connectivity thing, but
> graid?  Seriously?  That's an option for really cheap and some might say
> quite nasty pseudo-raid things you get on some desktop hardware.

The implementations from different vendors no doubt vary in quality 
quite a bit.  However, if a motherboard has a "software RAID device" 
(the euphemism we picked for the Handbook), those additional ports can 
almost certainly be used as plain non-RAID ports also.  Essentially, 
it's the same as JBOD mode on a real RAID controller.

So one way to look at this is based on how many ports are available on 
the motherboard.  If there are not enough ports for the drive array, 
another controller is needed anyway.  If there are enough ports, and the 
onboard controller can be set to non-RAID, then the option to use just 
the motherboard is available.