[gpfsug-discuss] mmfsd write behavior

[Aaron Knister]

Hi Everyone,

This is something that's come up in the past and has recently resurfaced 
with a project I've been working on, and that is-- it seems to me as 
though mmfsd never attempts to flush the cache of the block devices its 
writing to (looking at blktrace output seems to confirm this). Is this 
actually the case? I've looked at the gpl headers for linux and I don't 
see any sign of blkdev_fsync, blkdev_issue_flush, WRITE_FLUSH, or 
REQ_FLUSH. I'm sure there's other ways to trigger this behavior that 
GPFS may very well be using that I've missed. That's why I'm asking :)

I figure with FPO being pushed as an HDFS replacement using commodity 
drives this feature has *got* to be in the code somewhere.

-Aaron

-- 
Aaron Knister
NASA Center for Climate Simulation (Code 606.2)
Goddard Space Flight Center
(301) 286-2776