Justin Piszcz wrote:
Hardware: 1. Utilized (6) 400 gigabyte sata hard drives. 2. Everything is on PCI-e (965 chipset & a 2port sata card) Used the following 'optimizations' for all tests. # Set read-ahead. echo "Setting read-ahead to 64 MiB for /dev/md3" blockdev --setra 65536 /dev/md3 # Set stripe-cache_size for RAID5. echo "Setting stripe_cache_size to 16 MiB for /dev/md3" echo 16384 > /sys/block/md3/md/stripe_cache_size # Disable NCQ on all disks. echo "Disabling NCQ on all disks..." for i in $DISKS do echo "Disabling NCQ on $i" echo 1 > /sys/block/"$i"/device/queue_depth done
Given that one of the greatest benefits of NCQ/TCQ is with parity RAID, I'd be fascinated to see how enabling NCQ changes your results. Of course, you'd want to use a single SATA controller with a known good NCQ implementation, and hard drives known to not do stupid things like disable readahead when NCQ is enabled.
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