Your one pool is more occupied than the other pools and you want to migrate a few tdevs around. Or you want to retier the tdevs from FC to SATA pool or vice versa. Whatever is the reason, activity involves migrating tdevs and associated data from one pool to another. This is achieved by VLUN migration which requires SYMM_VMAX_OPTIMIZER license.
CAVEATS
Device ID remains same, just the data is transferred from one pool to another. So, in the end you will have X number of extra TDEVs bound to target pool and X number TDEVs unbound from source pool. After several such migration, source pool will be undersubscribed and targetpool will be oversubscribed. You might need to either unbind unused tdevs from target pool and bind them to source pool, or create new tdevs and bind them to source pool to get correct balancing. Also, the migration doesn’t take target pool’s subscription into account. If because of the migration target pool will become oversubscribed, it will still proceed. so be careful about the amount of free space.
PROCEDURE
I prefer to group the devices to be migrated in a text file instead of using device group because of the issues I’d with device groups.
1. All the devices in a dg should be of same type – either non-RDF or R1s or R2s. Extra work is needed in order to separate out the devices.
2. If devices are R1s or R2s, dg has to be created of that type, else it will give error while trying to add the devices to dg (default dg type is standard devices).
3. If the device is part of another device group on management host, then it can’t be added to new dg being created for VLUN migration.
To make this more difficult, the error messages displayed when attempting to do above don’t relate to the exact cause, and give no clue as to the actual reason. No such problems arise when using a flat file containing the list of device ids to be migrated. You can mix all types of devices in a single file and migrate them. Also no clean up is needed at the end such as deleting the device group.
In the example given below, three tdevs 0123,0124,0125 are being migrated from source_pool to dest_pool. The steps are as mentioned below:
1. Add the device ids to a flat file – one device id per line
# cat devids
0123
0124
01252. Choose a name for migration sessions (keep less than 25 chars) and validate the migration
# symmigrate -sid 1234 -name vlun_migration -f devids -tgt_pool -pool dest_pool validate -nop
'Validate' operation execution is in progress for
the device list in device file 'devids'. Please wait...
Validate Migration..............................................Started.
Validate Migration..............................................Done.
'Validate' operation successfully executed for
the device list in device file 'devids'.
3. Establish the migration session
# symmigrate -sid 1234 -name vlun_migration -f devids -tgt_pool -pool dest_pool establish -nop
'Establish' operation execution is in progress for
the device list in device file 'devids'. Please wait...
Validate Migration..............................................Started.
Validate Migration..............................................Done.
'Establish' operation successfully executed for
the device list in device file 'devids'.
4. Check the status of migration. Output shows status during migration and after completion
# symmigrate -sid 1234 -name vlun_migration query
Symmetrix ID: 000292601234
Invalid Status Done Flags
Src Tgt Tracks SRC => TGT (%) T Session Name
---- ---- -------- ------------ ---- ----- ----------------
0123 N/A 152208 SyncInProg 18 V vlun_migration
0124 N/A 152208 SyncInProg 18 V vlun_migration
0125 N/A 152208 SyncInProg 18 V vlun_migration
Total --------
Tracks 456624
MB(s) 38052.0
Done(%) 18
Flags:
(T)ype: V = The session is a Virtual Provisioning migration session.
C = The session is a configured migration session.
U = The session is an unconfigured migration session.
# symmigrate -sid 1234 -name vlun_migration query
Symmetrix ID: 000292601234
Invalid Status Done Flags
Src Tgt Tracks SRC => TGT (%) T Session Name
---- ---- -------- ------------ ---- ----- ----------------
0123 N/A 0 Migrated 100 V vlun_migration
0123 N/A 0 Migrated 100 V vlun_migration
0123 N/A 0 Migrated 100 V vlun_migration
Total --------
Tracks 0
MB(s) 0.0
Done(%) 100
Flags:
(T)ype: V = The session is a Virtual Provisioning migration session.
C = The session is a configured migration session.
U = The session is an unconfigured migration session.5. Verify the devices have been migrated
# symmigrate -sid 1234 -name vlun_migration verify -migrated -nop
All session(s) with name 'vlun_migration' are in 'Migrated' state.
6. Terminate the migration after it is complete
# symmigrate -sid 1234 -name vlun_migration terminate -nop
'Terminate' operation execution is in progress for
the session named 'vlun_migration'. Please wait...
Terminate Migration.............................................Started.
Terminate Migration.............................................Done.
'Terminate' operation successfully executed for
the session named 'vlun_migration'.
If you still want to use device group instead of flat file, then the commands would modify slightly as below:
# symdg create migrate_0123
# symld -sid 1234 -g migrate_0123 addall -range 0123:0125 (for non-RDF tdevs)
# symdg -sid 1234 -g migrate_0123 addall -devs 0123:0125 (for RDF tdevs)
# symmigrate -name vlun_migration -g migrate_0123 -tgt_pool -pool dest_pool validate -nop
# symmigrate -name vlun_migration -g migrate_0123 -tgt_pool -pool dest_pool establish -nop
# symmigrate -sid 1234 -name vlun_migration query
# symmigrate -sid 1234 -name vlun_migration verify -migrated -nop
# symmigrate -sid 1234 -name vlun_migration terminate -nop
Error when adding the device to device group
Group type mismtach
# symld -sid 1234 -g migrate_1234 add dev 0123
Group type is not valid for this operationThis means the device type and device group type don’t match. Check device group type using symdg show migrate_1234 and looking at the value for “Group Type”. Check the device type using symdev -sid 1234 show 1AA6 and lokking at the value for “RDF Type”. The value will be one of regular/rdf1/rdf2/rdf21. Change the device group type or device type or create a new device group and add the devices in.
symmgrate.exe crashes after running estabish on Windows management host with Solution Enabler 7.6.1
When session name being used is more than 25 characters, symmigrate crashes on SE761. Solution is to use SE762 or session name less than 25 chars.
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