[gpfsug-discuss] Biggest file that will fit inside an inode? 3876!

[Marc A Kaplan]

Pretty easy to determine experimentally, with a few trials....
And the answer is 3876 for an simple file with just a selinux EA which is 
apparently created by default on my test system.
So apparently there are actually only 220 bytes of metadata in this case 
(4096-3876=220).
As they say YMMV ;-)

[root at bog-wifi cmvc]# mmlsfs yy -i
flag                value                    description
------------------- ------------------------ 
-----------------------------------
 -i                 4096                     Inode size in bytes

[root at bog-wifi isize]# stat i387[67]
  File: ‘i3876’
  Size: 3876            Blocks: 0          IO Block: 262144 regular file

  File: ‘i3877’
  Size: 3877            Blocks: 16         IO Block: 262144 regular file


[root at bog-wifi isize]# ls -ild i3876
19406 -rw-r--r--. 1 root root 3876 Oct  3 10:39 i3876


tsdbfs yy

inode 19406
Inode 19406 [19406] snap 0 (index 14 in block 303):
  Inode address: 1:511600 size 4096 nAddrs 323
  indirectionLevel=INODE status=USERFILE
  objectVersion=2 generation=0x7C5599C4 nlink=1
  owner uid=0 gid=0 mode=0200100644: -rw-r--r--
  ...
  Data [3876]:
0000000000000000: 136D7B1F 1D29CA0C B59BC917 D9AE0220  *.m{..)..........*
0000000000000010: F18512CF 998AC02E DC6926FA 3FDC3EAF  *.........i&.?.>.*
 ...
0000000000000F20: EFF02209 00000000 05077365 6C696E75  *..".......selinu*
  trailer: 0x20005993FD8 diskAddrs 323 xattrLen 48 (free 3856/3904) res 
0,0,0
  overflow pri 0 vers 0 nsub 0 repl 1/2 DA Null
  [0] id 0x5 prefLen 8 keyLen 7 key security.selinux len 37 val 
'756E636F6E66696E65645F753A6F626A6563745F723A756E6C6162656C65645F743
A733000'



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