CentOS - Aug 2015 - [OFFTOPIC] integrated LSI 3008 :: number of hdd support

Hi guys! Unfortunately there is no offtopic list but the subject
is somehow related to centos as the OS is/will be centos :) 
So, under this thin cover i ask :
Is it possible that for a SAS controler like LSI 3008 that in specs
says that : "This high-performance I/O controller supports T-10 
data protection model and optical support, PCIe hot plugging, 
and up to 1,000 connected devices" in a vendor implementation
(motherboard integrated) to support only 8 (or 16) devices?
The technical support from the OEM told me that "the onboard 
SAS controller maximum amount of supported harddrives is 16pcs" 
and "if you are planning on using more than 16 drives then you
have to use a PCI-E card based SAS controller with external ports
(which Supermicro does not sell)"
and both statements sound insane to me!
First, because the specs for 3008 says something else and i dont know
how one can artificially reduce the number of supported hdds 
(beside the firmware - but why would one do that?) and
the second statement is just hogwash as the externl/internal status of
the ports have nothing to do with the sas cascading and the number of 
devices supported!! (and of course is really cheap to convert an internal 
port to an external port with a bracket)
So, i ask you guys that have more knowledge and expertise: was this 
Senior Application Engineer that answered me a total incompetent? 

Thank you!
Adrian

In my experience the mass market HBAs and RAID cards typically do support
only 8 or 16 drives.  For the internal variety in a standard rack-mount
server you'll usually see either 2 or 4 iPass cables (each of which support
4 drives) connected to the backplane.  The marketing material you've
referenced has a white lie in it: supporting more than 16 drives on a
single card is very likely only possible with an additional SAS expander
board.  I believe Supermicro does sell some pre-configured systems with
such hardware, but expect the throughput to fall through the floor if you
use such hardware.

Bottom line: the Supermicro application engineer knows what he's talking
about.

On Sun, Aug 30, 2015 at 1:13 AM, Adrian Sevcenco <Adrian.Sevcenco at
cern.ch>
wrote:
> Hi guys! Unfortunately there is no offtopic list but the subject
> is somehow related to centos as the OS is/will be centos :)
> So, under this thin cover i ask :
> Is it possible that for a SAS controler like LSI 3008 that in specs
> says that : "This high-performance I/O controller supports T-10
> data protection model and optical support, PCIe hot plugging,
> and up to 1,000 connected devices" in a vendor implementation
> (motherboard integrated) to support only 8 (or 16) devices?
> The technical support from the OEM told me that "the onboard
> SAS controller maximum amount of supported harddrives is 16pcs"
> and "if you are planning on using more than 16 drives then you
> have to use a PCI-E card based SAS controller with external ports
> (which Supermicro does not sell)"
> and both statements sound insane to me!
> First, because the specs for 3008 says something else and i dont know
> how one can artificially reduce the number of supported hdds
> (beside the firmware - but why would one do that?) and
> the second statement is just hogwash as the externl/internal status of
> the ports have nothing to do with the sas cascading and the number of
> devices supported!! (and of course is really cheap to convert an internal
> port to an external port with a bracket)
> So, i ask you guys that have more knowledge and expertise: was this
> Senior Application Engineer that answered me a total incompetent?
>
> Thank you!
> Adrian
>
>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos
>
>

On 08/30/2015 12:02 PM, Mike Mohr wrote:
> In my experience the mass market HBAs and RAID cards typically do support
> only 8 or 16 drives.  For the internal variety in a standard rack-mount
> server you'll usually see either 2 or 4 iPass cables (each of which
support
> 4 drives) connected to the backplane.  The marketing material you've
> referenced has a white lie in it: supporting more than 16 drives on a
> single card is very likely only possible with an additional SAS expander
> board.  I believe Supermicro does sell some pre-configured systems with
ok, then i should give a little detail : the purpose was to have an 1U
server as a head of a JBOD chassis that have 2 SAS backplanes.
The connection would be a simple SAS cascade to the backplanes.
> such hardware, but expect the throughput to fall through the floor if you
> use such hardware.
why? what is the difference between the silicon from a HBA card and the same
silicon
on motherboard?

The reason of my post is also to understand why is/is not possible..

Thank you,
Adrian
> Bottom line: the Supermicro application engineer knows what he's
talking
> about.
> 
> On Sun, Aug 30, 2015 at 1:13 AM, Adrian Sevcenco <Adrian.Sevcenco at
cern.ch>
> wrote:
> 
>> Hi guys! Unfortunately there is no offtopic list but the subject
>> is somehow related to centos as the OS is/will be centos :)
>> So, under this thin cover i ask :
>> Is it possible that for a SAS controler like LSI 3008 that in specs
>> says that : "This high-performance I/O controller supports T-10
>> data protection model and optical support, PCIe hot plugging,
>> and up to 1,000 connected devices" in a vendor implementation
>> (motherboard integrated) to support only 8 (or 16) devices?
>> The technical support from the OEM told me that "the onboard
>> SAS controller maximum amount of supported harddrives is 16pcs"
>> and "if you are planning on using more than 16 drives then you
>> have to use a PCI-E card based SAS controller with external ports
>> (which Supermicro does not sell)"
>> and both statements sound insane to me!
>> First, because the specs for 3008 says something else and i dont know
>> how one can artificially reduce the number of supported hdds
>> (beside the firmware - but why would one do that?) and
>> the second statement is just hogwash as the externl/internal status of
>> the ports have nothing to do with the sas cascading and the number of
>> devices supported!! (and of course is really cheap to convert an
internal
>> port to an external port with a bracket)
>> So, i ask you guys that have more knowledge and expertise: was this
>> Senior Application Engineer that answered me a total incompetent?
>>
>> Thank you!
>> Adrian
>>
>>
>> _______________________________________________
>> CentOS mailing list
>> CentOS at centos.org
>> https://lists.centos.org/mailman/listinfo/centos
>>
>>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos
>