Setting a value for the number of inodes

ECM systems often store a very large number of files in a File Storage Area.

The system under test had more than 5 million files in the File Storage Area and required a large number of filesystem inodes to manage the files. Spectrum Scale has a default inode limit that can become a threshold for the filesystem and lead to filesystem full conditions. There are a couple of indications that point to an inode full condition (for example, df command, mmdf command, GPFS™ and Linux™ log files).

This example shows an error indication on a tar restore operation:

... 
tar: content/79: Cannot mkdir: No space left on device

This example shows how the df, mmlsfs, and mmdf commands can be used:

# df -h
Filesystem                           Size  Used Avail Use% Mounted on
/dev/FSData                          600G   45G  556G   8% /data/FSData

# df -i
Filesystem                            Inodes  IUsed    IFree IUse% Mounted on
/dev/FSData                           614464 614464        0  100% /data/FSData

# mmlsfs FSData --inode-limit
flag                value                    description
------------------- ------------------------ -----------------------------------
 --inode-limit      614464                   Maximum number of inodes

# mmdf FSData -F
Inode Information
-----------------
Number of used inodes:          614464
Number of free inodes:               0
Number of allocated inodes:     614464
Maximum number of inodes:       614464

This example shows a GPFS log entry:

Tue Dec  8 10:14:57.454 2015: [W] Inode space 0 in file system FSData is 
approaching the limit for the maximum number of inodes.

This example shows a Linux log entry:

Dec  8 10:14:57 le2ep223 mmfs: Error=MMFS_SYSTEM_WARNING, ID=0x4DC797C6, 
Tag=6725521:   File system warning. Volume FSData. Reason: [W] Inode space 0 in 
file system FSData is approaching the limit for the maximum number of inodes.

Although the file system seems to have plenty of space left (df command reports only 8% usage), the inode information reveals that the file system runs out of inodes.

The solution for the problem is straightforwards - simply increase the inode limit for the Spectrum Scale filesystem. There is no need to recreate the file system.

This example shows how to increase the inode limit:

# mmchfs FSData --inode-limit 15M
Set maxInodes for inode space 0 to 15728640
Fileset root changed.

# mmdf FSData -F
Inode Information
-----------------
Number of used inodes:            4039
Number of free inodes:          610425
Number of allocated inodes:     614464
Maximum number of inodes:     15728640

For information about how to calculate a meaningful inode limit in the Spectrum Scale mmchfs command, proceed to this URL at the IBM® Knowledge Center:

https://www.ibm.com/docs/en/storage-scale/4.2.0

Then search for the mmchfs command.