[cc [email protected]] On Mon, Apr 21, 2014 at 10:58:53PM +0200, Speedy Milan wrote: > I want to report very slow deletion of 24 50GB files (in total 12 TB), > all present in the same folder.
total = 1.2TB? > OS is CentOS 6.4, with upgraded kernel 3.13.1. > > The hardware is a Supermicro server with 15x 4TB WD Se drives in MD > RAID 6, totalling 52TB of free space. > > XFS is formated directly on the RAID volume, without LVM layers. > > Deletion was done with rm -f * command, and it took upwards of 1 hour > to delete the files. > > File system was filled completely prior to deletion. Oh, that's bad. it's likely you fragmented the files into millions of extents? > rm was mostly waiting (D state), probably for kworker threads, and No, waiting for IO. > iostat was showing big HDD utilization numbers and very low throughput > so it looked like a random HDD workload was in effect. Yup, smells like file fragmentation. Non-fragmented 50GB files should be removed in a few milliseconds. but if you've badly fragmented the files, there could be 10 million extents in a 50GB file. A few milliseconds per extent removal gives you.... Cheers, Dave. -- Dave Chinner [email protected] -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
