I’ve been experimenting with interrupting the mender client during an OTA system update (deployment) instigated from our Mender Enterprise Server.
Essentially the experiment compared the time taken for updates with no interruption to the client versus update time taken when the client is interrupted (power reset).
The power reset interrupts were instigated when the progress indicator was at greater than 50%.
Mender version 2.5.1
System File Sizer : 400 MB
Probably as you would expect:-
The number of retries had to be increased to greater than zero to achieve a successful update when the Client was interrupted,.
The update time increased significantly when a power reset interrupted the client during an update, inferring that if a power interrupt occurs any part of the system file that has been uploaded to the client is lost and the file update has to transfer the whole file on the retry.
Which is not a good outcome in our situation where system updates would be to multiple clients over a possible limited bandwidth.
Can you confirm these results are as expected - that the mender file is not fragmented during file transfer and so any part of the file transferred is lost if the client is reset during this process?
Can you advise whether there are any options presently available, or planned for the future, which will cater for interruptions to the client device during a system update, i.e. have a file transfer history so only the remaining part of the system file needs to be sent after the interruption?