DRBD Slow Performance - 99.99 % [jbd2/drbd0-8] highiowait solution

Tired of checking iotop and seeing that your drbd partition is using 99.99% of io all the time and finding your drbd device performs slow in general?

This is especially an issue in versions of DRBD in the 8.3 tree in particular one documented case is on "8.3.13" but it likely applies to other devices.

The symptoms are that resyncing is fine and normal but any reasonable amount of activity is very slow and lagged and creates a high server load and consequently high io wait.  You may not notice it though until you apply a reasonable load or usage to the server and DRBD device.

In some kernels and some versions you may get the following error in dmesg

block drbd0: [drbd0_worker/1670] sock_sendmsg time expired, ko = 4294967295

*But we have seen many cases where the above error is not present (perhaps an older kernel or module does not recognize it is being blocked).

Here are some quick sysctl.conf kernel tuning tips that have changed a server's load from 10-18, to less than 1.

Add or edit these in sysctl.conf to solve the issue

net.ipv4.tcp_rmem = 131072  131072  10485760
net.ipv4.tcp_wmem = 131072  131072  10485760
vm.dirty_ratio = 10
vm.dirty_background_ratio = 4

 

This is a preferable way rather than hacking or changing DRBD settings by upgrading the userland or kernel manually or while it runs (results can be unpredictable) whereas this kernel tuning has virtually no risk or impact on DRBD except a positive one.


Tags:

drbd, jbd, highiowait, solutiontired, iotop, partition, io, performs, versions, documented, quot, applies, devices, resyncing, lagged, creates, server, consequently, usage, kernels, dmesg, _worker, sock_sendmsg, expired, ko, kernel, module, blocked, sysctl, conf, tuning, edit, ipv, tcp_rmem, tcp_wmem, vm, dirty_ratio, dirty_background_ratio, preferable, hacking, settings, upgrading, userland, manually, unpredictable, whereas, virtually,

Latest Articles

  • ImageMagick Convert PDF Not Authorized
  • ImageMagick Converted PDF to JPEG some files have a black background solution
  • Linux Mint Mate Customize the Lock screen messages and hide username and real name
  • Ubuntu/Gnome/Mint/Centos How To Take a partial screenshot
  • ssh how to verify your host key / avoid MIM attacks
  • Cisco IP Phone CP-8845 8800/8900 Series How To Reset To Factory Settings Instructions
  • ls how to list ONLY directories
  • How to encrypt your SSH private key file id_rsa
  • Linux Mint 18 Disable User Name List from showing on Login Screen
  • Firefox Cannot Hit Enter Key In Address Bar and Location History Not Working
  • Cisco Unified Communications Manager / CUCM IP 8.6,10,12 Install Error Solution
  • Ubuntu Debian Mint Linux SSHD OpenSSH Server Not Starting After Reboot Solution
  • nmap how to scan for all ports and not just the 1000 most common ports
  • Windows 7,8,10 and Server 2008, 2012, 2016, 2019 Read Only Attribute Won't Go Away
  • bind / named how to make a wildcard record and retain defined A records
  • Cisco Unified Communications Manager 12 Install Errors on Proxmox/KVM
  • Local Vs Universally Administered MAC Address NIC Refuses to come up
  • Cisco Unified Communications Manager 12 CUCM 12 - How To Enable Video Calling
  • Windows 7, 8, 10, Windows Server 2008, 2012, 2016, 2019 How To AC97 Audio Drivers and Other Unsigned Drivers
  • Cisco Unified Communications Manager / CUCM IP Telephony Definitions