Re: [HPDD-discuss] OSC and buffer cache throttling

Richard, Patrick The more I look at this, the more bizarre it gets. Now when I run this iozone test, I also track *cached_mb* for each OSC. This plot has the file position activity plot overlayed with the value of cached_mb for the 16 OST's that the file was stripped across. Things are predictable until the size of the file being written exceeds the amount of memory that Lustre can use for caching ( during the first write). After that, the competition for buffer memory by the OSC's starts. Further comment on the plot image. I still have not determined why *cached_mb* for any OSC never exceeds 8GB in the test cases where I stripe across 2,3,4,5,6,or 7 OSTs. In those cases the sum of the cached_mb for the used OSTs never exceeds the 50% of system memory limit. John On 2/3/2015 4:47 PM, Mohr Jr, Richard Frank (Rick Mohr) wrote: