[gpfsug-discuss] sublocks per block in GPFS 5.0

[Marc A Kaplan]

Apparently, a small mistake in that developer works post.
I always advise testing of new features on a scratchable system...
Here's what I see on my test system:

#mmcrfs mak -F /vds/mn.nsd -A no -T /mak -B 16M -f 1K -i 1K
Value '1024' for option '-f' is out of range.  Valid values are 4096 
through 524288.

# mmcrfs mak -F /vds/mn.nsd -A no -T /mak -B 16M -f 4K -i 1K
(runs okay)
# mmlsfs mak
flag                value                    description
------------------- ------------------------ 
-----------------------------------
 -f                 4096                     Minimum fragment (subblock) 
size in bytes
 -i                 1024                     Inode size in bytes
 -I                 32768                    Indirect block size in bytes
   ...
 -B                 16777216                 Block size
  ...
 -V                 18.00 (5.0.0.0)          File system version
  ...
 --subblocks-per-full-block 4096             Number of subblocks per full 
block
 ...




From:   valleru at cbio.mskcc.org
To:     gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:   03/30/2018 12:21 PM
Subject:        [gpfsug-discuss] sublocks per block in GPFS 5.0
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



Hello Everyone, 

I am a little bit confused with the number of sub-blocks per block-size of 
16M in GPFS 5.0.

In the below documentation, it mentions that the number of sub-blocks per 
block is 16K, but "only for Spectrum Scale RAID"

https://developer.ibm.com/storage/2018/01/11/spectrum-scale-variant-sub-blocks/

However, when i created the filesystem “without” spectrum scale RAID. I 
still see that the number of sub-blocks per block is 1024.

mmlsfs <filesystem> --subblocks-per-full-block
flag                value                    description
------------------- ------------------------ 
-----------------------------------
 --subblocks-per-full-block 1024             Number of subblocks per full 
block

So May i know if the sub-blocks per block-size really 16K? or am i missing 
something?

Regards,
Lohit_______________________________________________
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