In released GPFS, we only support one subblocks-per-fullblock in one file
system, like Sven mentioned that the subblocks-per-fullblock is derived by
the smallest block size of metadata and data pools, the smallest block size
decides the subblocks-per-fullblock and subblock size of all pools.
There's an enhancement plan to have pools with different block sizes and/or
subblocks-per-fullblock.
Thanks,
Yuan, Zheng Cai
From: "Andrew Beattie" <abeat...@au1.ibm.com>
To: gpfsug-discuss@spectrumscale.org
Date: 2018/08/02 09:10
Subject: Re: [gpfsug-discuss] Sub-block size not quite as expected on
GPFS 5 filesystem?
Sent by: gpfsug-discuss-boun...@spectrumscale.org
Stephen,
Sorry your right, I had to go back and look up what we were doing for
metadata.
but we ended up with 1MB block for metadata and 8MB for data and a 32k
subblock based on the 1MB metadata block size, effectively a 256k subblock
for the Data
Andrew Beattie
Software Defined Storage - IT Specialist
Phone: 614-2133-7927
E-mail: abeat...@au1.ibm.com
----- Original message -----
From: Stephen Ulmer <ul...@ulmer.org>
Sent by: gpfsug-discuss-boun...@spectrumscale.org
To: gpfsug main discussion list <gpfsug-discuss@spectrumscale.org>
Cc:
Subject: Re: [gpfsug-discuss] Sub-block size not quite as expected on GPFS
5 filesystem?
Date: Thu, Aug 2, 2018 11:00 AM
On Aug 1, 2018, at 8:11 PM, Andrew Beattie <abeat...@au1.ibm.com>
wrote:
[…]
which is probably why 32k sub block was the default for so many
years ....
I may not be remembering correctly, but I thought the default block size
was 256k, and the sub-block size was always fixed at 1/32nd of the block
size — which only yields 32k sub-blocks for a 1MB block size.
I also think there used to be something special about a 16k block size…
but I haven’t slept well in about a week, so I might just be losing it.
--
Stephen
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