Suboptimal performance due to file system being fully utilized
As a file system nears full utilization, it becomes difficult to find free space for new blocks. This impacts the performance of the write, append, and create operations.
Problem identification
On the GPFS node, issue the mmdf <fs> command to determine the available space.
disk disk size failure holds holds free KB free KB
name in KB group metadata data in full blocks in fragments
--------------- ------------- -------- ---------- -------- -------------------- -------------------
Disks in storage pool: system (Maximum disk size allowed is 18 TB)
DMD_NSD01 1756094464 101 Yes Yes 1732298752 ( 99%) 18688 ( 0%)
DMD_NSD09 1756094464 101 Yes Yes 1732296704 ( 99%) 13440 ( 0%)
DMD_NSD03 1756094464 101 Yes Yes 1732304896 ( 99%) 17728 ( 0%)
DMD_NSD07 1756094464 101 Yes Yes 1732300800 ( 99%) 14272 ( 0%)
DMD_NSD05 1756094464 101 Yes Yes 1732298752 ( 99%) 13632 ( 0%)
DMD_NSD06 1756094464 102 Yes Yes 1732300800 ( 99%) 13632 ( 0%)
DMD_NSD04 1756094464 102 Yes Yes 1732300800 ( 99%) 15360 ( 0%)
DMD_NSD08 1756094464 102 Yes Yes 1732294656 ( 99%) 13504 ( 0%)
DMD_NSD02 1756094464 102 Yes Yes 1732302848 ( 99%) 18688 ( 0%)
DMD_NSD10 1756094464 102 Yes Yes 1732304896 ( 99%) 18560 ( 0%)
------------- -------------------- -------------------
(pool total) 17560944640 17323003904 ( 99%) 157504 ( 0%)
============= ==================== ===================
(total) 17560944640 17323003904 ( 99%) 157504 ( 0%)
Inode Information
-----------------
Number of used inodes: 4048
Number of free inodes: 497712
Number of allocated inodes: 501760
Maximum number of inodes: 17149440The UNIX command df also can be used to determine the use percentage (Use%) of a file system. The following sample output displays a file system with 2% capacity used.
Filesystem Size Used Avail Use% Mounted on
/dev/gpfs1b 17T 227G 17T 2% /mnt/gpfs1bProblem resolution and verification
Use the mmadddisk command to add new disks or NSDs to increase the GPFS file system capacity. You can also delete unnecessary files from the file system by using the rm command in UNIX environments to free up space.
In the sample output below, the df –h and mmdf commands show the file system use percentage to be around 2%. This indicates that the file system has sufficient capacity available.
Filesystem Size Used Avail Use% Mounted on
/dev/gpfs1b 17T 211G 17T 2% /mnt/gpfs1b
disk disk size failure holds holds free KB free KB
name in KB group metadata data in full blocks in fragments
--------------- ------------- -------- ----------- ------ ------------------- -------------------
Disks in storage pool: system (Maximum disk size allowed is 18 TB)
DMD_NSD01 1756094464 101 Yes Yes 1734092800 ( 99%) 12992 ( 0%)
DMD_NSD09 1756094464 101 Yes Yes 1734094848 ( 99%) 14592 ( 0%)
DMD_NSD03 1756094464 101 Yes Yes 1734045696 ( 99%) 15360 ( 0%)
DMD_NSD07 1756094464 101 Yes Yes 1734043648 ( 99%) 10944 ( 0%)
DMD_NSD05 1756094464 101 Yes Yes 1734053888 ( 99%) 11584 ( 0%)
DMD_NSD06 1756094464 102 Yes Yes 1734103040 ( 99%) 11584 ( 0%)
DMD_NSD04 1756094464 102 Yes Yes 1734096896 ( 99%) 10048 ( 0%)
DMD_NSD08 1756094464 102 Yes Yes 1734053888 ( 99%) 14592 ( 0%)
DMD_NSD02 1756094464 102 Yes Yes 1734092800 ( 99%) 13504 ( 0%)
DMD_NSD10 1756094464 102 Yes Yes 1734062080 ( 99%) 13632 ( 0%)
------------- -------------------- -------------------
(pool total) 17560944640 17340739584 ( 99%) 128832 ( 0%)
============= ==================== ===================
(total) 17560944640 17340739584 ( 99%) 128832 ( 0%)
Inode Information
-----------------
Number of used inodes: 4075
Number of free inodes: 497685
Number of allocated inodes: 501760
Maximum number of inodes: 17149440