Disable AFM by using disable-online feature

Describes how to disable AFM by using disbale-online feature.

An AFM fileset can be disabled by using online disable feature and converted to an independent fileset. Online disable feature can be used runtime and there is no need to unlink the fileset or take any downtime for applications. After the fileset is disabled, files and directories in that fileset will no longer sync with the target or remote cluster. The online disable feature is available only on AFM read only (RO) and Local updates (LU) mode filesets. After the fileset is AFM disabled by using online disable features, the fileset cannot be converted to an AFM fileset.

To dissociate home or target and cache relationship of an AFM fileset, you can convert the AFM fileset to an independent fileset by using mmchfileset fsname filesetname -p afmTarget=disable-online. Thereafter, the fileset is an IBM Storage Scale independent fileset and file operations are not queued to home. An example is the case of NFS migration, where AFM fileset must be disabled after migration for local usage.

Note: Before you disable AFM by using disable-online feature ensure that all the files are cached (read completely) from the home or target fileset. Or, follow the interactive command to find the uncached files that needs to be prefetched.

The mmchfileset fsname filesetname -p afmTarget=disable-online command is interactive and provides an option to check weather files from home or remote fileset are cached into the AFM cache fileset. It is recommended that system administrators first verify the files that are ingested from home by providing “yes” input to verification of files and orphans prompt. After all the files are cached, the recommended step can be skipped and disable online can be run.

Example

Rotest1 is cache fileset

[root@cacheNode1 ~]# mmlsfileset fs1 rotest1 --afm -L


Filesets in file system 'fs1':
Attributes for fileset rotest1:
================================
Status                                  Linked
Path                                    /gpfs/fs1/rotest1
Id                                      52
Root inode                              3407875
Parent Id                               0
Created                                 Mon Jan 30 01:03:14 2023
Comment                                 
Inode space                             26      
Maximum number of inodes                100352
Allocated inodes                        100352
Permission change flag                  chmodAndSetacl
afm-associated                          Yes
Permission inherit flag                 inheritAclOnly
Target                                  nfs://homeNode1/gpfs/fs1/rotest
Mode                                    read-only
File Lookup Refresh Interval            30 (default)
File Open Refresh Interval              60 (default)
Dir Lookup Refresh Interval             60 (default)
Dir Open Refresh Interval               60 (default)
Async Delay                             disable
Expiration Timeout                      disable (default)
Last pSnapId                            0
Display Home Snapshots                  no (default)
Number of Gateway Flush Threads         4
Prefetch Threshold                      0 (default)
Eviction Enabled                        yes (default)
IO Flags                                0x0 (default)
IO Flags2                               0x0 (default)

Data in rotest1 fileset

[root@cacheNode1 ~]# ls -lR /gpfs/fs1/rotest1

/gpfs/fs1/rotest1:
total 16
drwxr-xr-x. 2 root root 8192 Jan 30 01:00 dir1
drwxr-xr-x. 2 root root 8192 Jan 30 01:00 dir2
-rw-r--r--. 1 root root    7 Jan 30 01:00 file1
-rw-r--r--. 1 root root    7 Jan 30 01:00 file2
-rw-r--r--. 1 root root    7 Jan 30 01:00 file3
-rw-r--r--. 1 root root    7 Jan 30 01:00 file4
-rw-r--r--. 1 root root    7 Jan 30 01:00 file5

/gpfs/fs1/rotest1/dir1:
total 0
-rw-r--r--. 1 root root 7 Jan 30 01:00 file1
-rw-r--r--. 1 root root 7 Jan 30 01:00 file2
-rw-r--r--. 1 root root 7 Jan 30 01:00 file3

/gpfs/fs1/rotest1/dir2:
total 0
-rw-r--r--. 1 root root 7 Jan 30 01:00 file1
-rw-r--r--. 1 root root 7 Jan 30 01:00 file2
-rw-r--r--. 1 root root 7 Jan 30 01:00 file3

Reading files as below (These files are cached)

[root@CacheNode1 ~]# cat /gpfs/fs1/rotest1/file* > /dev/null
[root@CacheNode1 ~]# 
[root@CacheNode1 ~]# cat /gpfs/fs1/rotest1/dir1/file* > /dev/null

Note: The files are not read from (as an example) /gpfs/fs1/rotest/dir2. These files are uncached.

Perform disable-online

[root@CacheNode1 ~]# mmchfileset fs1 rotest1 -p afmTarget=disable-online


Warning! Once disabled, AFM cannot be re-enabled on this fileset. Do you wish to continue? (yes/no) yes
Warning! Fileset should be verified for uncached files and orphans. If already verified, then skip this step.
Do you wish to verify same? (yes/no) yes
Verifying if all the data is cached. This may take a while...
mmchfileset: [E] Uncached files present, run prefetch first
Files list file: /var/mmfs/tmp/cmdTmpDir.mmchfileset.1152157/list-file.mmchfileset.1152157

Verification of cached files shows the files (uncached) in the list file


[root@CacheNode1 ~]# cat  /var/mmfs/tmp/cmdTmpDir.mmchfileset.1152157/list-file.mmchfileset.1152157
%2Fgpfs%2Ffs1%2Frotest1%2Fdir2%2Ffile2
%2Fgpfs%2Ffs1%2Frotest1%2Fdir2%2Ffile1
%2Fgpfs%2Ffs1%2Frotest1%2Fdir2%2Ffile3

Use the list that is provided by the above command for prefetching as below

[root@CacheNode1 ~]# mmafmctl fs1 prefetch  -j rotest1 --list-file  /var/mmfs/tmp/cmdTmpDir.mmchfileset.1152157/list-file.mmchfileset.1152157

mmafmctl: Performing prefetching of fileset: rotest1 
     Queued         ( Processed/     Total)         Failed                TotalData
                                                                  (approx in Bytes)
         3         (         3/         3)              0                       21

prefetch successfully queued at the gateway.
[root@CacheNode1 ~]# 

[root@CacheNode1 ~]# mmchfileset fs1 rotest1 -p afmTarget=disable-online
Warning! Once disabled, AFM cannot be re-enabled on this fileset. Do you wish to continue? (yes/no) yes
Warning! Fileset should be verified for uncached files and orphans. If already verified, then skip this step.
Do you wish to verify same? (yes/no) yes
Verifying if all the data is cached. This may take a while...
All the data is cached, rerun the command to disable AFM.
mmchfileset: Command failed. Examine previous error messages to determine cause.

Above command make sure that all the data is cached. Proceed to disable without verification

[root@CacheNode1 ~]# mmchfileset fs1 rotest1 -p afmTarget=disable-online

Warning! Once disabled, AFM cannot be re-enabled on this fileset. Do you wish to continue? (yes/no) yes
Warning! Fileset should be verified for uncached files and orphans. If already verified, then skip this step.
Do you wish to verify same? (yes/no) no
Fileset rotest1 changed.

After fileset is disabled, it will no longer associate to AFM target or home fileset

[root@CacheNode1 ~]# mmlsfileset fs1 rotest1 --afm -L


Filesets in file system 'fs1':

Attributes for fileset rotest1:
================================
Status                                  Linked
Path                                    /gpfs/fs1/rotest1
Id                                      52
Root inode                              3407875
Parent Id                               0
Created                                 Mon Jan 30 01:03:14 2023
Comment                                 
Inode space                             26      
Maximum number of inodes                100352
Allocated inodes                        100352
Permission change flag                  chmodAndSetacl
afm-associated                          No
Permission inherit flag                 inheritAclOnly