[gpfsug-discuss] du --apparent-size and quota

[Ulrich Sibiller]

On 6/1/21 6:08 PM, Kumaran Rajaram wrote:
>>> If I'm not mistaken even with SS5 created filesystems, 1 MiB FS block size implies 32 kiB sub blocks (32 sub-blocks).
> 
> Just to add: The /srcfilesys seemed to have been created with GPFS version 4.x which supports only 32 sub-blocks per block.
> 
> -T                 /srcfilesys              Default mount point
> -V                 16.00 (4.2.2.0)          Current file system version
>                     14.10 (4.1.0.4)          Original file system version
> --create-time      Tue Feb  3 11:46:10 2015 File system creation time
> -B                 1048576                  Block size
> -f                 32768                    Minimum fragment (subblock) size in bytes
> --subblocks-per-full-block 32               Number of subblocks per full block
> 
> 
> The /dstfilesys was created with GPFS version 5.x which support greater than 32 subblocks per block. /dstfilesys does have 512 subblocks-per-full-block with 8KiB subblock size since file-system blocksize is 4MiB.
> 
> 
> -T                 /dstfilesys              Default mount point
> -V                 23.00 (5.0.5.0)          File system version
> --create-time      Tue May 11 16:51:27 2021 File system creation time
> -B                 4194304                  Block size
> -f                 8192                     Minimum fragment (subblock) size in bytes
> --subblocks-per-full-block 512              Number of subblocks per full block
> 

Well, from the higher flexibility in terms of the number of subblocks I'd expect a lower disk usage 
instead of a higher one. Is this a wrong assumption? From 400G to 457G it's a ~13% increase!

> Beside the overhead, hard-links in the source FS (which, if I'm not mistaken, are not handled by "rsync" unless you specify "-H") and in some cases spare files can also explain the differences.

My rsync is using -AHS, so this should not be relevant here.

Uli

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