30.03.2011 19:20, Louis-David Mitterrand wrote: [] > /dev/mapper/cmd1 / xfs defaults,inode64,delaylog,logbsize=262144 0 0 > /dev/mapper/cmd1 / xfs defaults,inode64,delaylog,logbsize=262144 0 0 > >> [root@vault t]# dd if=/dev/zero of=/backup/t/big.file bs=32k count=32000 > > 1048576000 octets (1,0 GB) copiés, 0,870001 s, 1,2 GB/s > 1048576000 bytes (1.0 GB) copied, 9.11934 s, 115 MB/s Are you sure your LVM volumes are aligned to raid stripe size correctly? Proper alignment for raid levels with parity is _critical_, and with 8-drive raid6 you'll have 6 data disks in eash stripe, but since LVM can only align volumes to a power of two, you'll have 2 unaligned volumes after each aligned... Verify that the volume starts at the raid stripe boundary, maybe create new volume and recheck -- there should be quite dramatic speed difference like the above when you change from aligned to misaligned. /mjt -- 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
