Here is a summary of this week’s conference call. A few brief reminders:
- Conference calls are every Tuesday and open to all using either the FreeConferenceCall.com VoIP app or via a dial-in number: https://www.freeconferencecall.com/wall/zetalliance
- Each week’s call agenda can be found at: https://docs.google.com/document/d/1uUUDJpwp2CAylU6lxtbEdVcUX_qSbciyes6gLTWw2fY/edit
- Constructive feedback on these call summaries is always welcome.
August 4, 2020 Conference Call Summary
Migrating Zimbra Backup Data For A Data Center Migration
Noah P. shared that he is moving his Zimbra servers between data centers. He said he has found that 1-2 of his Zimbra mail stores are not able to complete the move within a scheduled maintenance window due to their large disk size, so he is using rsync to perform an initial online copy of each mail store’s disk to the new data center location outside of the maintenance window, so that a final rsync delta copy can be performed within the maintenance window for a fast cut-over. He asked if he should disable the real-time backup feature in Zimbra while the initial rsync & final delta copy is running, or if he should keep the real-time backups enabled. Cine recommended leaving the real-time scanner in Zimbra disabled until the final rsync delta copy is complete. He explained that leaving it enabled is likely to lead to concurrency or corruption issues in the backup data.
Unusual Mobile NG Sync Issues
Mark S. asked if anyone has seen unusual situations lately with Mobile NG. He described an issue he encountered while doing a search for a contact on his phone, which is setup to use EAS (Exchange ActiveSync) version 16.1, where the contact could not be found, but he confirmed the contact was definitely on his phone. Mark said he collected logs for Zimbra Support and opened a support case.
Mark shared another issue one of his customers reported, where the customer’s phone is setup to use ActiveSync and it repeatedly requests the mailbox folder list from the Zimbra server during synchronization, according to the Zimbra server logs. This results in the phone never completing a synchronization. He said he noticed this issue seems to have started in 8.8.15 Patch 11 and that it seems to be affecting both Android and iOS native email apps. He reported that he opened Zimbra Support case # 01043365.
Noah P. shared that since upgrading to EAS 16.1 in Zimbra 8.8.15 Patch 11, that he has seen an issue where message downloading seems to takes an extended amount of time to complete.
Cine said one possible reason for the issues that Mark and Noah shared may be due to EAS phone clients that seem to have an undocumented internal time out limit for ActiveSync to complete a synchronization. If an EAS client does not receive the complete mailbox folder list within the EAS client’s time out limit from the Zimbra server, the EAS client seems to unexpectedly abort the request, then the client restarts the synchronization again, even while the Zimbra server continues to send the mailbox folder list. This makes the situation worse when the EAS client self aborts the synchronization process. This problem is particularly apparent when an EAS client attempts to synchronize a Zimbra mailbox with a large number of folders. Noah said one of his customers that is experiencing this issue has 1,600 folders in their mailbox, while another has 400 folders.
Mark S. suggested that someone should create a list of all of the limits that apply to ActiveSync sessions, such as the maximum number of mailbox folders supported, maximum number of characters allowed in a folder name, and so on. Cine said the challenge in writing a document describing the limits in ActiveSync, is that ActiveSync is a client-driven protocol, where each phone manufacturer sets their own arbitrary limits. He also explained that it is very difficult to tell which Android versions support which EAS versions. To illustrate the differences in EAS implementations, he shared that Google has 900 lines for code for their ActiveSync implementation while Samsung has 1,800 lines of code, with both implementations seeming to accomplish the same functionality. He said this is puzzling as to why one implementation is twice the size of the other.
Native Zimbra 9 App For Phones/Tablets
John E. asked everyone on the call if having a native Zimbra 9 app for phones/tablets would make a positive difference for this customers experiencing issues with native ActiveSync implementations on their customers’ phones. John explained that the Modern UI in Zimbra 9 is packaged as a PWA (Progressive Web App; https://en.wikipedia.org/wiki/Progressi ... pplication) which should be installable on phones/tablets, although with some limited capabilities. Mark S. said that asking customers to login to their email with a web browser on their phones is usually a non-starter. John E. explained that a PWA allows the app to function either in disconnected or connected mode and that it looks and functions just like a native phone app. PWAs have limitations related to notifications, and running in the background, as compared to native apps. Randy L. mentioned that this sounds very similar to the Adobe PhoneGap project, where it is possible to write phone apps in HTML code, which PhoneGap can then compile in to an installable app that essentially runs as a chromeless web browser on a phone. John also described some of the restrictions that apply to app distribution through the Google and Apple app stores.