[gpfsug-discuss] How to prove that data is in inode

Billich Heinrich Rainer (ID SD) heinrich.billich at id.ethz.ch
Wed Jul 17 12:41:54 BST 2019


How can I prove that data of a small file is stored in the inode (and not on a data nsd)?

We have a filesystem with 4k inodes on Scale 5.0.2 , but it seems there is no file data in the inodes?

I would expect that 'stat' reports 'Blocks: 0'  for a small file, but I see 'Blocks:1'.



I tried

[]# rm -f test; echo hello > test
[]# ls -ls test
1 -rw-r--r-- 1 root root 6 Jul 17 13:11 test
[root at testnas13ems01 test]# stat test
  File: ‘test’
  Size: 6         	Blocks: 1          IO Block: 1048576 regular file
Device: 2dh/45d	Inode: 353314      Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2019-07-17 13:11:03.037049000 +0200
Modify: 2019-07-17 13:11:03.037331000 +0200
Change: 2019-07-17 13:11:03.037259319 +0200
 Birth: -
[root at testnas13ems01 test]# du test
1	test
[root at testnas13ems01 test]# du -b test
6	test
[root at testnas13ems01 test]#


# mmlsfs f****
flag                value                    description
------------------- ------------------------ -----------------------------------
 -f                 32768                    Minimum fragment (subblock) size in bytes
 -i                 4096                     Inode size in bytes
 -I                 32768                    Indirect block size in bytes
 -m                 1                        Default number of metadata replicas
 -M                 2                        Maximum number of metadata replicas
 -r                 1                        Default number of data replicas
 -R                 2                        Maximum number of data replicas
 -j                 cluster                  Block allocation type
 -D                 nfs4                     File locking semantics in effect
 -k                 nfs4                     ACL semantics in effect
 -n                 32                       Estimated number of nodes that will mount file system
 -B                 1048576                  Block size
 -Q                 user;group;fileset       Quotas accounting enabled
                    user;group;fileset       Quotas enforced
                    user;group;fileset       Default quotas enabled
 --perfileset-quota Yes                      Per-fileset quota enforcement
 --filesetdf        Yes                      Fileset df enabled?
 -V                 20.01 (          Current file system version
                    15.01 (          Original file system version
 --create-time      ***** 2017 File system creation time
 -z                 No                       Is DMAPI enabled?
 -L                 33554432                 Logfile size
 -E                 Yes                      Exact mtime mount option
 -S                 relatime                 Suppress atime mount option
 -K                 whenpossible             Strict replica allocation option
 --fastea           Yes                      Fast external attributes enabled?
 --encryption       No                       Encryption enabled?
 --inode-limit      1294592                  Maximum number of inodes in all inode spaces
 --log-replicas     0                        Number of log replicas
 --is4KAligned      Yes                      is4KAligned?
 --rapid-repair     Yes                      rapidRepair enabled?
 --write-cache-threshold 0                   HAWC Threshold (max 65536)
 --subblocks-per-full-block 32               Number of subblocks per full block
 -P                 system;data              Disk storage pools in file system
 --file-audit-log   No                       File Audit Logging enabled?
 --maintenance-mode No                       Maintenance Mode enabled?
 -d                 ******
-A                 yes                      Automatic mount option
 -o                 nfssync,nodev            Additional mount options
 -T                 /****                  Default mount point
 --mount-priority   0                        Mount priority

Heinrich Billich
ETH Zürich
Tel.: +41 44 632 72 56
heinrich.billich at id.ethz.ch

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