Adding the space or disks in GPFS Filesystem

          Steps to add the disks to the filesystem

step 1 : Before adding a disks in the GPFS ,take the details of GPFS disks .

      # mmlsnsd  and also verify using the command


       # mmlsnsd
         File system   Disk name    NSD servers
         --------------------------------------------------------------------------
          gpfs0         nsd08        (directly attached)

          gpfs0         nsd09        (directly attached)


      #mmlsnsd -m  >> this gives details of the corresponding disk and ID .
 

Step 2 : Before adding the disk in GPFS filesystem ,we need to create the 
         GPFS Disk using the command mmcrnsd.
       
         For creating a nsd we need to create a disk descriptor file . The format of the file is as follows .
         it is not necessary to to define all fields.
     

         disk-Name:Primaryserver:backupserver:diskusage:failuregroup:desiredname:storagepool
       
  I am going to add hdisk1,hdisk2,hdisk3,hdisk4,hdisk5,hdisk6 to the filesystem gpfs0 .


    Create the file /tmp/abhi/gpfs-disks.txt .

hdisk1:::dataAndMetadata::nsd01::
hdisk2:::dataAndMetadata::nsd02::
hdisk3:::dataAndMetadata::nsd03::
hdisk4:::dataAndMetadata::nsd04::
hdisk5:::dataAndMetadata::nsd05::
hdisk6:::dataAndMetadata::nsd06::



#mmcrnsd -F /tmp/abhi/gpfs-disks.txt

mmcrnsd: Processing disk hdisk1
mmcrnsd: Processing disk hdisk2
mmcrnsd: Processing disk hdisk3
mmcrnsd: Processing disk hdisk4
mmcrnsd: Processing disk hdisk5
mmcrnsd: Processing disk hdisk6
mmcrnsd: Propagating the cluster configuration data to all
  affected nodes.  This is an asynchronous process.

Once the command is sucessful ,we can see that NSD names corresponding to the disks in lspv output.



# lspv
hdisk0          00c334b6af00e77b                    rootvg          active
hdisk1          none                                nsd01
hdisk2          none                                nsd02
hdisk3          none                                nsd03
hdisk4          none                                nsd04
hdisk5          none                                nsd05
hdisk6          none                                nsd06
hdisk8          none    nsd08
hdisk9          none      nsd09


Also  we need to verify using the mmlsnsd command .

# mmlsnsd
 File system   Disk name    NSD servers
--------------------------------------------------------------------------
 gpfs0         nsd08        (directly attached)

 gpfs0         nsd09        (directly attached)

(free disk)   nsd01        (directly attached)

(free disk)   nsd02        (directly attached)

(free disk)   nsd03        (directly attached)

(free disk)   nsd04        (directly attached)

(free disk)   nsd05        (directly attached)

(free disk)   nsd06        (directly attached)


step 3 -- after this we need to add the disks to the filesystems

Before adding the disk to the GPFS filesystems ,we need to create a disk descriptor file .
since while creating the NSD ,we have already defined some of the parameters so no need to define it again here .
                  Below fields "diskname",datausage ,failure group,storagepool should be defined

by default GPFS Cluster will have one storage pool that is "system" but we can define many storage pools as per our requirement.

diskname:::diskusage:failuregroup::storagepool:

    cat /tmp/abhi/gpfs-disk.txt
nsd01:::dataAndMetadata:-1::system
nsd02:::dataAndMetadata:-1::system
nsd03:::dataAndMetadata:-1::system

#mmadddisk gpfs -F /tmp/cg/gpfs-disk.txt -r  >>>-r option is used here for re-balancing the data on all the new disks

Note: Rebalancing of data is I/O intensive job . it is not preferred to use this option during peak load .

Once added verify the disk size using the df -gt and also the output of #mmlsnsd.

# mmlsnsd
 File system   Disk name    NSD servers
--------------------------------------------------------------------------
 gpfs0         nsd08        (directly attached)

 gpfs0         nsd09        (directly attached)

 gpfs0         nsd01        (directly attached)

 gpfs0         nsd02        (directly attached)

 gpfs0         nsd03        (directly attached)

 gpfs0         nsd04        (directly attached)

 gpfs0         nsd05        (directly attached)

 gpfs0         nsd06        (directly attached)