mdadm - RAID6 Tweaks

Apr 24, 2016

After reconfiguring a server to use RAID6 with LUKS instead of RAID10 I noticed the sequential performance was abysmal. This is mostly due to the fact that the strip_cache_size is set to 512 by default.

md0 is the RAID array with 4 disks.

# Read ahead
blockdev --setra 65536 /dev/md0

# Stripe cache
echo 32768 > /sys/block/md0/md/stripe_cache_size

# Disable NCQ
echo 1 > /sys/block/sda/device/queue_depth
echo 1 > /sys/block/sdb/device/queue_depth
echo 1 > /sys/block/sdc/device/queue_depth
echo 1 > /sys/block/sdd/device/queue_depth

# Deadline scheduler can help with multi-threaded work loads
echo 'deadline' > /sys/block/sda/queue/scheduler
echo 'deadline' > /sys/block/sdb/queue/scheduler
echo 'deadline' > /sys/block/sdc/queue/scheduler
echo 'deadline' > /sys/block/sdd/queue/scheduler

Before: 79 MB/s writes After: 179 MB/s writes

That’s a big improvement!

linux Related

• Linux 4G LTE Failover

  Aug 22, 2020

• Backing Up VM Images to Wasabi (or S3, B2, etc.)

  May 20, 2020

• Headless Fluxbox / TightVNC

  Apr 21, 2019

• Backup Disks Using Netcat

  Nov 3, 2018

• Benchmarking KVM/ZFS on Ubuntu 18.04 (raidz2)

  Oct 29, 2018

• EZ Arch Encrypted Installation

  Sep 1, 2018

• Hiding Symbols in ELF Binaries

  Jul 4, 2018

Comments