[gpfsug-discuss] GPFS systemd and gpfs.gplbin

[Jonathan Buzzard]

So you need to apply a kernel update and that means a new gpfs.gplbin 
:-( So after going around the houses with several different approaches 
on this I have finally settled on what IMHO is a most elegant method of 
ensuring the right gpfs.gplbin version is installed for the kernel that 
is running and thought I would share it.

This is assuming you don't like the look of the compile it option IBM 
introduced. You may well not want compilers installed on nodes for 
example, or you just think compiling the module on hundreds of nodes is 
suboptimal.

This exact version works for RHEL and it's derivatives. Modify for your 
preferred distribution. It also assumes you have a repository setup with 
the relevant gpfs.gplbin package.

The basics are to use the "ExecStartPre" option of a unit file in 
systemd. So because you don't want to be modifying the unit file 
provided by IBM something like the following

mkdir -p /etc/systemd/system/gpfs.service.d
echo -e "[Service]\nExecStartPre=-/usr/bin/yum --assumeyes install 
gpfs.gplbin-%v" >/etc/systemd/system/gpfs.service.d/install-module.conf
systemctl daemon-reload

How it works is that the %v is a special systemd variable which is the 
same as "uname -r". So before it attempts to start gpfs, it attempts to 
install the gpfs.gplbin RPM for the kernel you are running on. If 
already installed this is harmless and if it's not installed it gets 
installed.

How you set that up on your system is up to you, xCAT postscript, RPM 
package, or a configuration management solution all work. I have gone 
for a very minimal RPM I call gpfs.helper

We then abuse the queuing system on the HPC cluster to schedule a 
"admin" priority job that runs as soon as the node becomes free, which 
does a yum update and then restarts the node.


JAB.

-- 
Jonathan A. Buzzard                         Tel: +44141-5483420
HPC System Administrator, ARCHIE-WeSt.
University of Strathclyde, John Anderson Building, Glasgow. G4 0NG