Dne 30.12.2011 0:28, Michele Codutti napsal(a): > Hi all, I'm writing to this mailing list because I cannot figure out why I had some performance issues with my three WD20EARS (2TB Western Digital "Green" 4K/AF drive). > These drives has a (sequential) write throughput around 100MB/s. When I combine them in a RAID0 configuration the throughput is around 300 MB/s and in a RAID1 configuration they preserve a single drive performance of 100MB/s. > When I combine all three drives in a RAID5 configuration the (individual) performance falls around 40MB/s. > I get the same performance level when I do individual misaligned writes (ex: dd if=/dev/zero bs=6K of=/dev/sda). > The drives are not partitioned. I'm using the default chunk size (512K) and the default metadata superblock version (1.2). > I had not formatted the RAID or any single drive during my test i had directly used the raw devices. > I'm using a 11.10 ubuntu with 3.0.0 linux kernel and 3.1.4 mdadm. > The hardware is a HP microserver. > > Could you give me some advice? > Thanks in advance. > > Michele-- > 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 There must be some misalignment somewhere :( Do all drives really report as 4K to the OS - physical_block_size, logical_block_size under /sys/block/sdX/queue/ ?? NB: how does it perform with partitions starting at sector 2048 (check all disks with fdisk -lu /dev/sdX). HTH, Z. -- 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
