Administrator Guide

Appendix A Storage array cabling
22 Dell EMC Ready Solutions for HPC BeeGFS High Capacity Storage | ID 424
4.4 Performance tuning
Multiple parameters can be configured to achieve optimal system performance depending on intended
workload patterns. This section shows the tuning parameters that we configured on the BeeGFS testbed
system in the Dell HPC and AI Innovation lab.
• Set the number of processes for the superuser to 50000 in order to improve performance.
• Tuned the IO scheduler settings for the storage block devices on the storage servers by adding the
following lines to /etc/rc.local and make /etc/rc.local executable afterwards:
for mdev in /dev/mapper/storage* ; do
dev=$(basename $(readlink -f "$mdev"))
echo "$dev"
echo deadline > /sys/block/${dev}/queue/scheduler
echo 2048 > /sys/block/${dev}/queue/nr_requests
echo 4096 > /sys/block/${dev}/queue/read_ahead_kb
echo 256 > /sys/block/${dev}/queue/max_sectors_kb
done
$ chmod +x /etc/rc.local
• Tuned the IO scheduler settings for the metadata block devices on the metadata servers by adding
the following lines to /etc/rc.local and make /etc/rc.local executable afterwards:
for mdev in /dev/mapper/storage* ; do
dev=$(basename $(readlink -f "$mdev"))
echo "$dev"
echo deadline > /sys/block/${dev}/queue/scheduler
echo 128 > /sys/block/${dev}/queue/nr_requests
echo 128 > /sys/block/${dev}/queue/read_ahead_kb
echo 256 > /sys/block/${dev}/queue/max_sectors_kb
done
$ chmod +x /etc/rc.local
• Disabled transparent huge pages by creating /etc/tmpfiles.d/90-beegfs-hugepages.conf
file with the following content:
# Recommended configuration for BeeGFS servers
# Disable transparent hugepages
# Type Path Mode UID GID Age
Argument w /sys/kernel/mm/transparent_hugepage/khugepaged/defrag - -
- - 0
w /sys/kernel/mm/transparent_hugepage/defrag - - - -
never
w /sys/kernel/mm/transparent_hugepage/enabled - - - -
never
• Tuned virtual memory settings by adding the following lines to /etc/sysctl.d/90-beegfs.conf:
# VM ratios recommended for BeeGFS
vm.dirty_background_ratio = 5
vm.dirty_ratio = 20
vm.min_free_kbytes = 262144x
vm.vfs_cache_pressure = 50