The information about how much sync is required and how much has been done will only be populated when a sync is actually in progress. You should see these fields populated shortly after restarting the partnership.
Original Message:
Sent: Fri May 02, 2025 08:24 AM
From: T Masteen
Subject: PBHA Establishing duration
Hello Chris Canto,
I'm testing with PBHA. Have a host generating load on a ESX datastore. On PBHA FS5300, I see load (writes) on one of the Flashsystems. After stopping the Partnership I seen de load move to the other Flashsystem. Volumes and Vdisks stay online.
Now I would like to see the Sync_Required and Sync_Remaining values, but the output is blank
IBM_FlashSystem:FS5300_Noord:superuser>lsvolumegroupreplication -bytes 0
id 0
name FS5300_Noord_VG01
replication_policy_id
replication_policy_name
ha_replication_policy_id 0
ha_replication_policy_name FS5300_HA-Policy
local_location 1
location1_system_id
location1_system_name
location1_replication_mode production
location1_status healthy
location1_running_recovery_point
location1_fixed_recovery_point
location1_within_rpo
location1_volumegroup_id 0
location1_sync_required
location1_sync_remaining
location1_previous_replication_mode
location1_last_write_time
location2_system_id
location2_system_name
location2_replication_mode disconnected
location2_status disconnected
location2_running_recovery_point
location2_fixed_recovery_point
location2_within_rpo
location2_volumegroup_id 1
location2_sync_required
location2_sync_remaining
location2_previous_replication_mode
location2_last_write_time
link1_status disconnected
partition_id 0
partition_name FS5300_Partition
checkpoint_achieved
I know there is data to sync, and it takes a while before Partition is good again.
Any ideas?
Thanks.
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TMasteen
Original Message:
Sent: Thu May 01, 2025 01:32 PM
From: Chris Canto
Subject: PBHA Establishing duration
...And if you were looking to script something to generate a partition-level summary, you could specify the -bytes parameter on the command to make it easier to sum the numbers together for multiple volume groups in a partition, rather than the human-readable units that are displayed by default.
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Chris Canto
Software Developer
IBM
Hursley
Original Message:
Sent: Thu May 01, 2025 01:28 PM
From: Chris Canto
Subject: PBHA Establishing duration
On 870, there isn't a partition-level view with this information. However, you can use the CLI to view the amount of data remaining to sync for a volume group, so you could use that, looping over each volume group in a particular partition. This won't give you the estimated time remaining, but will at least allow you to monitor progress and calculate a percentage etc.
See https://www.ibm.com/docs/en/sanvolumecontroller/8.7.0?topic=commands-lsvolumegroupreplication
There are a pair of "sync_required" and "sync_remain" fields for each location, e.g.
- location1_sync_required - Indicates the total amount of data that must be copied to update the recovery point for the volume group in location 1 of the replication policy.
- location1_sync_remaining - Indicates the remaining amount of data that must be copied to update the recovery point for the volume group in location 1 of the replication policy. This value can be subtracted from the location1_sync_required value to obtain the amount of data that has already been copied.
Hope that helps.
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Chris Canto
Software Developer
IBM
Hursley
Original Message:
Sent: Thu May 01, 2025 12:26 PM
From: T Masteen
Subject: PBHA Establishing duration
Hello Chris, Thank you for your reply.
The SV3 clusters are running 8.7.0.x. We are a kind of a LTS shop.
Is it possible to retrieve the information (via scripts) from the system and/or (change)volumes or something similar with the existing 8.7.0 code?
We will also run the test without any load on the system to see the difference.
Thanks.
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TMasteen
Original Message:
Sent: Thu May 01, 2025 09:30 AM
From: Chris Canto
Subject: PBHA Establishing duration
The time taken will depend on the size of the configuration, in terms of the number of resources that need to be created on the remote system (think number of volume groups, volumes, hosts, host mappings) and the amount of data that needs to be copied to sync the new volumes (i.e. the size of the volumes). Typically, the time taken to sync the configuration is small compared to the time taken to sync the data.
The 8.7.3 release (release note here) added:
- Enhancements for monitoring high availability and disaster recovery, showing progress and estimated completion time for volume group and partition synchronization.
Are you testing on 8.7.3, or something earlier?
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Chris Canto
Software Developer
IBM
Hursley
Original Message:
Sent: Thu May 01, 2025 09:25 AM
From: T Masteen
Subject: PBHA Establishing duration
Hello all,
We are working on some test scenarios with PBHA. What we notice is that it takes quite a while before the HA status goes from estabishing to normal.
Can we find out (with the CLI for example) what the progress is of the establising? Is there a guideline for how long this can take? Or what the process depends on?
Thanks,
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TMasteen
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