On Fri, Jul 13, 2007 at 03:36:46PM -0400, Justin Piszcz wrote: > On Fri, 13 Jul 2007, Jon Collette wrote: > > >Wouldn't Raid 6 be slower than Raid 5 because of the extra fault tolerance? > > http://www.enterprisenetworksandservers.com/monthly/art.php?1754 - 20% > >drop according to this article > > > >His 500GB WD drives are 7200RPM compared to the Raptors 10K. So his > >numbers will be slower. > >Justin what file system do you have running on the Raptors? I think thats > >an interesting point made by Joshua. > > I use XFS: When it comes to bandwidth, there is good reason for that. > >>>Trying to stick with a supported config as much as possible, I need to > >>>run ext3. As per usual, though, initial ext3 numbers are less than > >>>impressive. Using bonnie++ to get a baseline, I get (after doing > >>>'blockdev --setra 65536' on the device): > >>>Write: 136MB/s > >>>Read: 384MB/s > >>> > >>>Proving it's not the hardware, with XFS the numbers look like: > >>>Write: 333MB/s > >>>Read: 465MB/s > >>> Those are pretty typical numbers. In my experience, ext3 is limited to about 250MB/s buffered write speed. It's not disk limited, it's design limited. e.g. on a disk subsystem where XFS was getting 4-5GB/s buffered write, ext3 was doing 250MB/s. http://oss.sgi.com/projects/xfs/papers/ols2006/ols-2006-paper.pdf If you've got any sort of serious disk array, ext3 is not the filesystem to use.... > >>>How many folks are using these? Any tuning tips? Make sure you tell XFS the correct sunit/swidth. For hardware raid5/6, sunit = per-disk chunksize, swidth = number of *data* disks in array. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
