GPFS Tuning Parameters

This section is taken from IBM GPFS Tuning Parameters

Option 1: To view GPFS Configuration Parameters

# mmlsconfig
Configuration data for cluster nsd-nas:
----------------------------------------
myNodeConfigNumber 1
clusterName nsd1-nas
clusterId 111111111111
autoload yes
minReleaseLevel 3.4.0.7
dmapiFileHandleSize 32
maxMBpS 2000
maxblocksize 4m
pagepool 1000m
adminMode allToAll

File systems in cluster nsd1-nas:
---------------------------------
/dev/gpfs1

Option 2: Detailed Dump of configuration

# mmfsadm dump config
afmAsyncDelay 15
afmAtimeXattr 0
afmDirLookupRefreshInterval 60
afmDirOpenRefreshInterval 60
afmDisconnectTimeout 60
afmExpirationTimeout disable
afmFileLookupRefreshInterval 30
afmFileOpenRefreshInterval 30
afmLastPSnapId 0
afmMode 1
afmNumReadGWs 0
afmNumReadThreads 1
afmParallelReadChunkSize 134217728
afmParallelReadThreshold disable
afmReadBufferSize 33554432
afmReadPrefetchThreshold 2
.....
.....

Option 3: Change Configuration Parameters

# mmchconfig pagepool=256M

Use -i to make the change permanent and affect the running GPFS daemon immediately.
Use -I to affect the GPFS daemon only (reverts to saved settings on restart)

Parameters
(For more information, see GPFS Tuning Parameters)

leaseRecoveryWait
logfile size
GPFSCmdPortRange
maxBufferDescs
maxFilesToCache
maxMBpS
maxMissedPingTimeout
maxReceiverThreads
maxStatCache
minMissedPingTimeout
nfsPrefetchStrategy
nsdMaxWorkerThreads
numaMemoryInterleave
pagepool
opensslLibName
prefetchPct
prefetchThreads
readReplicaPolicy
seqDiscardThreshold
sharedMemLimit
socketMaxListenConnections
socketRcvBufferSize
socketSndBufferSize
verbsLibName
verbsrdmasperconnection
verbsrdmaspernode
worker1Threads
worker3Threads
writebehindThreshold

Total Reconfiguration of GPFS from scratch again

If you have messed things up in the configuration and wish to redo the entire setup again, you have to do the following. From our training at GPFS, there are 2 advisable ways. The first one is the recommended way. The latter one is the “nuclear” option

Step 1: Unmount the GPFS file system

# mmumount /gpfs1 -a

Step 2: Delete GPFS file system. Deleting the file system and descriptors are important so that will not create issues during the subsequent file creation attempt

# mmdelfs /gpfs1

Step 3: Delete GPFS NSDs. Deleting the NSDs are important so that they will not create issues during the subsequent NSD creation.

# mmdelnsd nsd1-nas
# mmdelnsd nsd2-nas

Step 4: Shutdown GPFS daemons

# mmshutdown -a

Step 5: Delete the GPFS cluster

# mmdelnode -a

The “nuclear” option

Step 1: Unmount the GPFS file system
(Caution: GPFS cluster will be  erased and data will be lost)

# mmunmount /gpfs1 -a
# mmfsadm cleanup

Step 2: Delete selected configuration files on all nodes

# rm -f /var/mmfs/etc/mmfs.cfg
# rm -f /var/mmfs/gen/*
# rm -f /var/mmfs/tmp/*