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

[Adrian Sevcenco]

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
>