Hardware RAID or software for ZFS

[Andrei Brezan]

On 11/18/14 16:28, bsd at todoo.biz wrote:
> Hi,
>
>
> 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.

If your disks are SATA you can use the disks in a similar fashion as 
JBOD from a PCI-E controller as the onboard controller and backplane 
should recognize them. If they are SAS than you need a controller for 
them. For ZFS I don't think that anything than exposing the disk as is 
to ZFS gives any benefits, ZFS is designed to write directly on disk 
without any raid between it and the hardware layer. The caching 
algorithm of a raid system might tell ZFS that data was written to disk 
when data is still in the controller's cache for example.

I've never heard of a setup with ZFS on top of gmirror or gstripe but my 
gut feeling is that they might not play well together as they try to 
address similar, if not identical, issues.

>
> I would like to have some feedback on various aspects :
>
> 1. performance
> 2. usability
> 3. problem one might have encountered
>
>
>
> Thanks for your feedback.
>
> G.B.

Regards,

Andrei