Very slow downloading of images and studies using zip download

General
1

Hello, if any recommendations please send our way

. We are experiencing slow retrieving of images. using windows server 2025 . ver. Orthanc 25.7.0 while downloading zip for the study from orthanc expl 2 download option.
This is a new vm server hosted on azure , due to we ran out of space on old the on prem server.

we moved imaging storage folder and index files and loaded new version of Orthanc. also sending to another pacs (Nuance Powershare) takes a very long time, not sure if i have something incorrect or something on the server 2025 thats is causing the slowness.

I’ve tried adjusting the config but still not very good, the cpu and drives and ram seems to be very stable and not peaking very much so it doesn’t seem to be a hardware resource issue.

It was working pretty well on the on prem setup. we are currently using the sql Lite that comes built in we have 3.5 tb of images stored, so moving to another db may take a bit. Please let me know if any other info is needed.

I’ll add the config and log files

Thanks for any help
,
orthanc1.json (48.2 KB)
Orthanc.log.20250820-.txt (147.4 KB)

2

Hi

As soon as you transfer or download studies, Orthanc needs to read hundreds or thousands of files. Therefore, you are probably very quickly hitting the VM IOPS limit and then your disk bandwidth probably gets throttled.

You may check the logs in verbose mode, they show the reading throughput of each file…

Best,

Alain

3

Thank you @alainmazy appreciate that insight , looking into that issue.

is it possible for your thoughts on another ticket i raised out migration to postgre also.

Thanks again.