On Wed, Sep 29, 2010 at 12:58 PM, Peter Kjellstrom <cap at nsc.liu.se> wrote: > On Wednesday 29 September 2010, Boris Epstein wrote: >> On Wed, Sep 29, 2010 at 11:53 AM, James A. Peltier <jpeltier at sfu.ca> wrote: >> > | However, given the size of the device I assume that this is a raid of >> > | some >> > | sort. You'll want to make sure to run mkfs.xfs with the proper stripe >> > | parameters to get the alignment right. Also, you may want to make sure >> > | your >> > | LVM or partition table is properly aligned. > ... >> I am wondering if I need to worry about stripe and width though as >> mine resides on a logical volume residing on a hardware-controlled >> RAID 6 device (i.e., one slice as far as the OS is concerned). > > That is why you need to consider it. If the device is aligned on stripe size > (chunk size * (number of drives - 2 for raid6 parity)) and the filesystem is > made aware it can put stuff (files, metadata, etc.) so that a minimum of > stripes are touched (less I/O done). > > /Peter > >> Boris. > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > > Well, you are interfering with the hardware RAID controller which copies around and stripes data as it sees fit. I am not sure with this many levels of abstraction I can gain any measurable performance improvement by adjusting the XFS to the controller's hypothetical behaviour. Boris.