From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: md question re: max_hw_sectors_kb Date: Wed, 04 May 2011 13:58:05 -0400 Message-ID: References: <4DC0639E.1070707@sgi.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <4DC0639E.1070707@sgi.com> (Michael Reed's message of "Tue, 03 May 2011 15:20:46 -0500") Sender: linux-raid-owner@vger.kernel.org To: Michael Reed Cc: linux-raid@vger.kernel.org, neilb@suse.de, Jeremy Higdon , Hannes Reinecke List-Id: linux-raid.ids >>>>> "Michael" == Michael Reed writes: Michael> There is code in blk_queue_make_request() which lowers the Michael> default value from INT_MAX to BLK_SAFE_MAX_SECTORS, which is Michael> 255. This is generally lower than all the underlying devices Michael> with which I use md. Yeah, the SAFE value is there to appease legacy low-level drivers. Michael> As md appears to be a stacking driver, i.e., it calls Michael> disk_stack_limits() for each member of a volume, it would seem Michael> reasonable for md to use the, INT_MAX setting for Michael> max_hw_sectors_kb instead of BLK_SAFE_MAX_SECTORS. Your fix is functionally correct. However, another case just popped up this week where we need to distinguish between stacking driver and LLD defaults. So I think we should try to handle this at the block layer instead of explicitly tweaking this knob in MD. I'll get this fixed up and will CC: you on the patch. -- Martin K. Petersen Oracle Linux Engineering