[gpfsug-discuss] Sub-block size wrong on GPFS 5 filesystem?
Marc A Kaplan
makaplan at us.ibm.com
Wed Aug 1 19:47:31 BST 2018
I guess that particular table is not the whole truth, nor a specification,
nor a promise, but a simplified summary of what you get when there is just
one block size that applies to both meta-data and data-data.
You have discovered that it does not apply to systems where metadata has a
different blocksize than data-data.
My guesstimate (speculation!) is that the deployed code chooses one
subblocks-per-full-block parameter and applies that to both. Which would
explain the results we're seeing. Further is seems the the mmlsfs command
assumes at least in some places that there is only one subblocks-per-block
parameter...
Looking deeper into code, is another story for another day -- but I'll say
that there seems to be sufficient flexibility that if this were deemed a
burning issue, there could be futher "enhancements..." ;-)
From: "Buterbaugh, Kevin L" <Kevin.Buterbaugh at Vanderbilt.Edu>
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date: 08/01/2018 02:24 PM
Subject: Re: [gpfsug-discuss] Sub-block size wrong on GPFS 5
filesystem?
Sent by: gpfsug-discuss-bounces at spectrumscale.org
Hi Marc,
Thanks for the response … I understand what you’re saying, but since I’m
asking for a 1 MB block size for metadata and a 4 MB block size for data
and according to the chart in the mmcrfs man page both result in an 8 KB
sub block size I’m still confused as to why I’ve got a 32 KB sub block
size for my non-system (i.e. data) pools? Especially when you consider
that 32 KB isn’t the default even if I had chosen an 8 or 16 MB block
size!
Kevin
?
Kevin Buterbaugh - Senior System Administrator
Vanderbilt University - Advanced Computing Center for Research and
Education
Kevin.Buterbaugh at vanderbilt.edu - (615)875-9633
On Aug 1, 2018, at 12:21 PM, Marc A Kaplan <makaplan at us.ibm.com> wrote:
I haven't looked into all the details but here's a clue -- notice there is
only one "subblocks-per-full-block" parameter.
And it is the same for both metadata blocks and datadata blocks.
So maybe (MAYBE) that is a constraint somewhere...
Certainly, in the currently supported code, that's what you get.
From: "Buterbaugh, Kevin L" <Kevin.Buterbaugh at Vanderbilt.Edu>
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date: 08/01/2018 12:55 PM
Subject: [gpfsug-discuss] Sub-block size wrong on GPFS 5
filesystem?
Sent by: gpfsug-discuss-bounces at spectrumscale.org
Hi All,
Our production cluster is still on GPFS 4.2.3.x, but in preparation for
moving to GPFS 5 I have upgraded our small (7 node) test cluster to GPFS
5.0.1-1. I am setting up a new filesystem there using hardware that we
recently life-cycled out of our production environment.
I “successfully” created a filesystem but I believe the sub-block size is
wrong. I’m using a 4 MB filesystem block size, so according to the mmcrfs
man page the sub-block size should be 8K:
Table 1. Block sizes and subblock sizes
+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
| Block size | Subblock size |
+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
| 64 KiB | 2 KiB |
+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
| 128 KiB | 4 KiB |
+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
| 256 KiB, 512 KiB, 1 MiB, 2 | 8 KiB |
| MiB, 4 MiB | |
+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
| 8 MiB, 16 MiB | 16 KiB |
+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
However, it appears that it’s 8K for the system pool but 32K for the other
pools:
flag value description
------------------- ------------------------
-----------------------------------
-f 8192 Minimum fragment (subblock)
size in bytes (system pool)
32768 Minimum fragment (subblock)
size in bytes (other pools)
-i 4096 Inode size in bytes
-I 32768 Indirect block size in bytes
-m 2 Default number of metadata
replicas
-M 3 Maximum number of metadata
replicas
-r 1 Default number of data
replicas
-R 3 Maximum number of data
replicas
-j scatter Block allocation type
-D nfs4 File locking semantics in
effect
-k all ACL semantics in effect
-n 32 Estimated number of nodes
that will mount file system
-B 1048576 Block size (system pool)
4194304 Block size (other pools)
-Q user;group;fileset Quotas accounting enabled
user;group;fileset Quotas enforced
none Default quotas enabled
--perfileset-quota No Per-fileset quota enforcement
--filesetdf No Fileset df enabled?
-V 19.01 (5.0.1.0) File system version
--create-time Wed Aug 1 11:39:39 2018 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 101095424 Maximum number of inodes
--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 128 Number of subblocks per full
block
-P system;raid1;raid6 Disk storage pools in file
system
--file-audit-log No File Audit Logging enabled?
--maintenance-mode No Maintenance Mode enabled?
-d
test21A3nsd;test21A4nsd;test21B3nsd;test21B4nsd;test23Ansd;test23Bnsd;test23Cnsd;test24Ansd;test24Bnsd;test24Cnsd;test25Ansd;test25Bnsd;test25Cnsd
Disks in file system
-A yes Automatic mount option
-o none Additional mount options
-T /gpfs5 Default mount point
--mount-priority 0 Mount priority
Output of mmcrfs:
mmcrfs gpfs5 -F ~/gpfs/gpfs5.stanza -A yes -B 4M -E yes -i 4096 -j scatter
-k all -K whenpossible -m 2 -M 3 -n 32 -Q yes -r 1 -R 3 -T /gpfs5 -v yes
--nofilesetdf --metadata-block-size 1M
The following disks of gpfs5 will be formatted on node testnsd3:
test21A3nsd: size 953609 MB
test21A4nsd: size 953609 MB
test21B3nsd: size 953609 MB
test21B4nsd: size 953609 MB
test23Ansd: size 15259744 MB
test23Bnsd: size 15259744 MB
test23Cnsd: size 1907468 MB
test24Ansd: size 15259744 MB
test24Bnsd: size 15259744 MB
test24Cnsd: size 1907468 MB
test25Ansd: size 15259744 MB
test25Bnsd: size 15259744 MB
test25Cnsd: size 1907468 MB
Formatting file system ...
Disks up to size 8.29 TB can be added to storage pool system.
Disks up to size 16.60 TB can be added to storage pool raid1.
Disks up to size 132.62 TB can be added to storage pool raid6.
Creating Inode File
8 % complete on Wed Aug 1 11:39:19 2018
18 % complete on Wed Aug 1 11:39:24 2018
27 % complete on Wed Aug 1 11:39:29 2018
37 % complete on Wed Aug 1 11:39:34 2018
48 % complete on Wed Aug 1 11:39:39 2018
60 % complete on Wed Aug 1 11:39:44 2018
72 % complete on Wed Aug 1 11:39:49 2018
83 % complete on Wed Aug 1 11:39:54 2018
95 % complete on Wed Aug 1 11:39:59 2018
100 % complete on Wed Aug 1 11:40:01 2018
Creating Allocation Maps
Creating Log Files
3 % complete on Wed Aug 1 11:40:07 2018
28 % complete on Wed Aug 1 11:40:14 2018
53 % complete on Wed Aug 1 11:40:19 2018
78 % complete on Wed Aug 1 11:40:24 2018
100 % complete on Wed Aug 1 11:40:25 2018
Clearing Inode Allocation Map
Clearing Block Allocation Map
Formatting Allocation Map for storage pool system
85 % complete on Wed Aug 1 11:40:32 2018
100 % complete on Wed Aug 1 11:40:33 2018
Formatting Allocation Map for storage pool raid1
53 % complete on Wed Aug 1 11:40:38 2018
100 % complete on Wed Aug 1 11:40:42 2018
Formatting Allocation Map for storage pool raid6
20 % complete on Wed Aug 1 11:40:47 2018
39 % complete on Wed Aug 1 11:40:52 2018
60 % complete on Wed Aug 1 11:40:57 2018
79 % complete on Wed Aug 1 11:41:02 2018
100 % complete on Wed Aug 1 11:41:08 2018
Completed creation of file system /dev/gpfs5.
mmcrfs: Propagating the cluster configuration data to all
affected nodes. This is an asynchronous process.
And contents of stanza file:
%nsd:
nsd=test21A3nsd
usage=metadataOnly
failureGroup=210
pool=system
servers=testnsd3,testnsd1,testnsd2
device=dm-15
%nsd:
nsd=test21A4nsd
usage=metadataOnly
failureGroup=210
pool=system
servers=testnsd1,testnsd2,testnsd3
device=dm-14
%nsd:
nsd=test21B3nsd
usage=metadataOnly
failureGroup=211
pool=system
servers=testnsd1,testnsd2,testnsd3
device=dm-17
%nsd:
nsd=test21B4nsd
usage=metadataOnly
failureGroup=211
pool=system
servers=testnsd2,testnsd3,testnsd1
device=dm-16
%nsd:
nsd=test23Ansd
usage=dataOnly
failureGroup=23
pool=raid6
servers=testnsd2,testnsd3,testnsd1
device=dm-10
%nsd:
nsd=test23Bnsd
usage=dataOnly
failureGroup=23
pool=raid6
servers=testnsd3,testnsd1,testnsd2
device=dm-9
%nsd:
nsd=test23Cnsd
usage=dataOnly
failureGroup=23
pool=raid1
servers=testnsd1,testnsd2,testnsd3
device=dm-5
%nsd:
nsd=test24Ansd
usage=dataOnly
failureGroup=24
pool=raid6
servers=testnsd3,testnsd1,testnsd2
device=dm-6
%nsd:
nsd=test24Bnsd
usage=dataOnly
failureGroup=24
pool=raid6
servers=testnsd1,testnsd2,testnsd3
device=dm-0
%nsd:
nsd=test24Cnsd
usage=dataOnly
failureGroup=24
pool=raid1
servers=testnsd2,testnsd3,testnsd1
device=dm-2
%nsd:
nsd=test25Ansd
usage=dataOnly
failureGroup=25
pool=raid6
servers=testnsd1,testnsd2,testnsd3
device=dm-6
%nsd:
nsd=test25Bnsd
usage=dataOnly
failureGroup=25
pool=raid6
servers=testnsd2,testnsd3,testnsd1
device=dm-6
%nsd:
nsd=test25Cnsd
usage=dataOnly
failureGroup=25
pool=raid1
servers=testnsd3,testnsd1,testnsd2
device=dm-3
%pool:
pool=system
blockSize=1M
usage=metadataOnly
layoutMap=scatter
allowWriteAffinity=no
%pool:
pool=raid6
blockSize=4M
usage=dataOnly
layoutMap=scatter
allowWriteAffinity=no
%pool:
pool=raid1
blockSize=4M
usage=dataOnly
layoutMap=scatter
allowWriteAffinity=no
What am I missing or what have I done wrong? Thanks…
Kevin
?
Kevin Buterbaugh - Senior System Administrator
Vanderbilt University - Advanced Computing Center for Research and
Education
Kevin.Buterbaugh at vanderbilt.edu- (615)875-9633
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