On 05/04/2011 07:58 PM, Martin K. Petersen wrote:
"Michael" == Michael Reed<mdr@xxxxxxx> 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.
Could you please CC me or linux-raid as well? I have a similar patch for
raid1 and while I'm not working on Lustre anymore, I know that Lustre
also always has a another kernel patch for raid5...
Thanks,
Bernd
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