Ah, one more thing. With XFS there is an online defragmenter -- it runs every night on my cluster. Performance on a fresh, empty system will not match a used one that has become fragmented.
On Apr 22, 2010, at 1:02 AM, stephen mulcahy wrote: > Hi, > > I've been tweaking our cluster roll-out process to refine it. While > doing so, I decided to check if XFS gives any performance benefit over EXT4. > > As per a comment I read somewhere on the hbase wiki - XFS makes for > faster formatting of filesystems (it takes us 5.5 minutes to rebuild a > datanode from bare metal to a full Hadoop config on top of Debian > Squeeze using XFS) versus EXT4 (same bare metal restore takes 9 minutes). > > However, TeraSort performance on a cluster of 45 of these data-nodes > shows XFS is slower (same configuration settings on both installs other > than changed filesystem), specifically, > > mkfs.xfs -f -l size=64m DEV > (mounted with noatime,nodiratime,logbufs=8) > gives me a cluster which runs TeraSort in about 23 minutes > > mkfs.ext4 -T largefile4 DEV > (mounted with noatime) > gives me a cluster which runs TeraSort in about 18.5 minutes > > So I'll be rolling our cluster back to EXT4, but thought the information > might be useful/interesting to others. > > -stephen > > > XFS config chosen from notes at > http://everything2.com/index.pl?node_id=1479435 > > -- > Stephen Mulcahy, DI2, Digital Enterprise Research Institute, > NUI Galway, IDA Business Park, Lower Dangan, Galway, Ireland > http://di2.deri.ie http://webstar.deri.ie http://sindice.com
