errors=remount-ro,noatime,nouser_xattr,barrier=0
(Replace sdXY with your partition name)
sudo tune2fs -l /dev/sdXY | fgrep has_journal
Unmount filesystem (If root filesystem then mount read-only) and then:
tune2fs -O ^has_journal /dev/sdXY
noatime,nodiratime,logbufs=8,logbsize=256k,nobarrier
(Replace sdX with your device name)
####
## IO Scheduler
####
# First, set an appropriate IO scheduler for file servers:
echo deadline > /sys/block/sdX/queue/scheduler
# Now give the IO scheduler more flexibility by increasing the number of schedulable requests:
echo 4096 > /sys/block/sdX/queue/nr_requests
# To improve throughput for sequential reads, increase the maximum amount of read-ahead data.
# The actual amount of read-ahead is adaptive,
# so using a high value here won't harm performance for small random access.
echo 4096 > /sys/block/sdX/queue/read_ahead_kb
####
## Virtual memory settings
####
# To avoid long IO stalls (latencies) for write cache flushing
# in a production environment with very different workloads,
# you will typically want to limit the kernel dirty (write) cache size:
echo 5 > /proc/sys/vm/dirty_background_ratio
echo 10 > /proc/sys/vm/dirty_ratio
# Assigning slightly higher priority to inode caching helps
# to avoid disk seeks for inode loading:
echo 50 > /proc/sys/vm/vfs_cache_pressure
# Decrease swappiness to prevent swapping as much as possible
echo 1 > /proc/sys/vm/swappiness
# Buffering of file system data requires frequent memory allocation.
# Raising the amount of reserved kernel memory will enable faster and more reliable
# memory allocation in critical situations.
# Raise the corresponding value to 64MB if you have less than 8GB of memory,
# otherwise raise it to at least 256MB:
echo 262144 > /proc/sys/vm/min_free_kbytes
# For RHEL 7.x and other distributions, it is recommended to have transparent huge pages enabled:
echo always > /sys/kernel/mm/transparent_hugepage/enabled
echo always > /sys/kernel/mm/transparent_hugepage/defrag
####
## Process scheduler
####
# There's a kernel parameter that determines how long a migrated process has to be running
# before the kernel will consider migrating it again to another core.
# The sysctl name is sched_migration_cost_ns, default value 50000 (that's ns so 0.5 ms).
# Forking servers, like PostgreSQL or Apache, scale to much higher levels of concurrent
# connections if this is made larger, by at least an order of magnitude:
echo 5000000 > /proc/sys/kernel/sched_migration_cost_ns
# Another parameter that can dramatically impact forking servers is sched_autogroup_enabled.
# This setting groups tasks by TTY, to improve perceived responsiveness on an interactive system.
# On a server with a long running forking daemon, this will tend to keep child processes from
# migrating away as soon as they should.
# It can be disabled like so:
echo 0 > /proc/sys/kernel/sched_autogroup_enabledsudo /etc/rc.local or reboot
Giving CouchDB IO priority with ionice: sudo ionice -p $(pidof beam.smp) -c 1 -n 0.
This can also be done in a systemd unit:
IOSchedulingClass=1
IOSchedulingPriority=0