Hi Leigh, On Thu, Feb 17, 2011 at 3:49 PM, Leigh Orf <[email protected]> wrote:
> 3. There is a command (lfs) on kraken which controls striping patterns. > Could I perhaps see better performance by mucking with striping? I have > looked through http://www.nics.tennessee.edu/io-tips "I/O Tips - Lustre > Striping and Parallel I/O" but did not come back with any clear message > about how I should modify the default settings. Yes, this is the first thing you should check. I don't have an account on Kraken and can't verify, but my guess is that the default is only a few a stripes out of hundreds of available OSTs (= Lustre I/O servers). For large paralel I/O you want as many stripes as possible, since this will aggregate the bandwidth of the individual OSTs. There is a hard limit of 160 stripes in Lustre, even though some I/O systems (like the one serving JaguarPF at ORNL) have hundreds of OSTs. So I would start by setting your striping to 160 (I'm assuming Kraken has >=160 OSTs). You may also see some benefit to increasing the stripe size from 1mb (default on most Lustre file systems) to 4mb or 8mb. I will try to respond to your other questions later tonight... Mark _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
