topic Re: Snapmirror Synchronous isn't synching immediately in ONTAP Discussions

Snapmirror Synchronous isn't synching immediately

Stormont — Wed, 04 Jun 2025 10:56:42 GMT

We have two clusters that are both running 9.7P5. On Cluster A, we have a volume that has a CIFS share associated with it. We then have a Snapmirror Sync relationship with Cluster B. For some reason, when a user updates a file in the original volume, the changes aren't replicated to Cluster B until 5 minutes after the hour (or a manual update). Our understanding is that a write to the source volume would be written immediately to the source and destination?

Below is the information for the relationship in case it helps:

Oriole::> snapmirror show -destination-path oriole-svm:sm_s_prj004_NTFS

Source Path: cardinal-svm:prj004_NTFS

Destination Path: oriole-svm:sm_s_prj004_NTFS

Relationship Type: XDP

Relationship Group Type: none

SnapMirror Schedule: -

SnapMirror Policy Type: sync-mirror

SnapMirror Policy: Sync

Tries Limit: -

Throttle (KB/sec): unlimited

Mirror State: Snapmirrored

Relationship Status: InSync

File Restore File Count: -

File Restore File List: -

Transfer Snapshot: -

Snapshot Progress: -

Total Progress: -

Network Compression Ratio: -

Snapshot Checkpoint: -

Newest Snapshot: snapmirror.477874a4-49e1-11e6-934f-00a098a22fa1_2153295841.2020-08-18_110500

Newest Snapshot Timestamp: 08/18 11:05:00

Exported Snapshot: snapmirror.477874a4-49e1-11e6-934f-00a098a22fa1_2153295841.2020-08-18_110500

Exported Snapshot Timestamp: 08/18 11:05:00

Healthy: true

Unhealthy Reason: -

Destination Volume Node: Oriole-01

Relationship ID: 60d303d6-db52-11ea-9aa3-90e2ba9be160

Current Operation ID: -

Transfer Type: -

Transfer Error: -

Current Throttle: -

Current Transfer Priority: -

Last Transfer Type: resync

Last Transfer Error: -

Last Transfer Size: 2.97KB

Last Transfer Network Compression Ratio: 1:1

Last Transfer Duration: 0:0:12

Last Transfer From: cardinal-svm:prj004_NTFS

Last Transfer End Timestamp: 08/10 17:57:43

Progress Last Updated: -

Relationship Capability: 8.2 and above

Lag Time: 0:0:0

Identity Preserve Vserver DR: -

Volume MSIDs Preserved: -

Is Auto Expand Enabled: -

Number of Successful Updates: 187

Number of Failed Updates: 0

Number of Successful Resyncs: 1

Number of Failed Resyncs: 0

Number of Successful Breaks: 0

Number of Failed Breaks: 0

Total Transfer Bytes: 15879

Total Transfer Time in Seconds: 12

Re: Snapmirror Synchronous isn't synching immediately

Sergey_Osipov — Wed, 19 Aug 2020 08:39:40 GMT

This is expected behavior. User reads to a SnapMirror Synchronous (SM-S)
destination volume are redirected to the latest exported Snapshot for the SnapMirror
Synchronous relationship

If the SnapMirror Synchronous relationship is healthy and "InSync", writes to the source
volume are still being replicated synchronously and will be available in case of a
disaster recovery scenario.

https://www.netapp.com/us/media/tr-4733.pdf

Chapter 3.12

Here is a KB as well

https://kb.netapp.com/Advice_and_Troubleshooting/Data_Protection_and_Security/SnapMirror/SnapMirror_Synchronous_doesn't_show_changes_on_destination_volume

Re: Snapmirror Synchronous isn't synching immediately

Stormont — Wed, 19 Aug 2020 12:58:56 GMT

That is unfortunate, as our understanding was that we would be able to instantly see the file in location A and B immediately after a change was made. We have an application that needs to be able to read from the secondary copy, but it sounds like we can't make the sync happen more often than 30 minutes.

Re: Snapmirror Synchronous isn't synching immediately

paul_stejskal — Thu, 20 Aug 2020 15:58:44 GMT

The technology was designed for as close to possible RTO, not DR type file mirroring. You may want to look at Flexcache for your solution needs. It seems like the network is close so that should offer good performance.

We also have a cloud based product GFC that can be used in physical environments (from Talon). Perhaps this may meet your needs?

If you're unsure, a discussion with the account team is definitely a possibility to ensure you are getting the products that meet your needs.