svn commit: r204648 - head/sys/dev/ciss

[Attila Nagy]

Alexander Motin wrote:
> Attila Nagy wrote:
>   
>> Alexander Motin wrote:
>>     
>>> Author: mav
>>> Date: Wed Mar  3 17:58:41 2010
>>> New Revision: 204648
>>> URL: http://svn.freebsd.org/changeset/base/204648
>>>
>>> Log:
>>>   Several changes to fix livelock under high load, introduced by r203489:
>>>   - change the way in which command queue overflow is handled;
>>>   - do not expose to CAM two command slots, used for driver's internal purposes;
>>>   - allow driver to use up to 1024 command slots, instead of 256 before.
>>>   
>>>       
>> Thank you for hunting this bug down. Do you plan to increase the maximum
>> logical device limit as well?
>>     
>
> Not sure. I just have no idea why this limitation was enforced. Even if
> I personally don't see problems from increasing it, it would be nice if
> somebody more aware of this driver tell whether it is correct for all
> supported hardware. I just don't have any. Thank you for provided
> access. If nobody responds, we may try our luck in CURRENT.
>   
>From the VCS history it seems this limit is there from the very first
revision, which was made for the Compaq SmartRAID 5* line. Those were
parallel SCSI controllers, so 15 was a sane value there (you couldn't
attach more than 15 devices to the bus).
The change came with the new SAS controllers, which can have external
connectors, so a lot of drives (and logical drives) can be attached to them.

I use SAS (P800) controllers with increased limit without any ill
effects, but can try older ones (SCSI: 5i, 6i) too if needed.