Messages in this thread | | | Date | Wed, 28 May 2008 11:40:24 -0400 | From | Chris Snook <> | Subject | Re: Performance Characteristics of All Linux RAIDs (mdadm/bonnie++) |
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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.
-- Chris
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