During pureScale instance creation, you might run into instance creation failed condition. Under some circumstances, it is possible that db2icrt does not perform a proper clean-up for GPFS and it may fail next time complaining that the disk is already a GPFS disk. When NSDs are created, GPFS writes the inode table at several places for recovery purposes and by simply using dd command to wipe out first few KB at starting of the disk may not be sufficient at times and GPFS signatures are still there.
What is the easiest way to clean / remove GPFS signatures from the disk?
You can use the following commands to first create a GPFS cluster, start it and then create NSD and then delete it. This will remove the disk cleanly.
#!/bin/bash
DOMAIN=zinox.com
NODE=db2test01
PEERDOMAIN=gpfs
DISK=/dev/sdc
mmcrcluster -N $NODE:manager-quorum -p $NODE \
-R /usr/bin/scp -r /usr/bin/ssh -C $PEERDOMAIN -U $DOMAIN
mmchlicense server --accept -N $NODE
mmstartup -a
mmgetstate -a
sleep 10
cat << EOF | tee disk.txt
%nsd:
device=$DISK
nsd=nsd01
usage=dataAndMetadata
EOF
mmcrnsd -F disk.txt -v no
mmdelnsd -F disk.txt
mmshutdown
mmdelnode $NODE
mmlscluster
The most important commands are mmcrnsd -F disk.txt -v no using -v switch to no and then mmdelnsd -F disk.txt.