Challenges after upgrade to 3.5 from 2.7

Change-Id: I8f1b51b8c89d250a48a2f04daf754747dd8f94ec
diff --git a/schedule.md b/schedule.md
index b4b0366..e7390e5 100644
--- a/schedule.md
+++ b/schedule.md
@@ -47,6 +47,7 @@
 | 08:30     | Breakfast / Check-in
 | 09:30     | [Tracking Git Repository Health with Metrics: Insights and Challenges](lightning-talks/what-s-up-in-your-repo.md)
 | 09:45     | [Creating Quotas using Task Parker](lightning-talks/quotas-using-task-parker.md)
+| 10:00     | [Challenges after Qualcomm's upgrade to 3.5 from 2.7](sessions/challenges-after-upgrading-to-3.5-from-2.7.md)
 | 12:30     | Lunch & Networking
 | TBD       | [Q&A with the Gerrit maintainers](sessions/maintainers-qa.md)
 | 17:00     | End of the day
diff --git a/sessions/challenges-after-upgrading-to-3.5-from-2.7.md b/sessions/challenges-after-upgrading-to-3.5-from-2.7.md
new file mode 100644
index 0000000..083b813
--- /dev/null
+++ b/sessions/challenges-after-upgrading-to-3.5-from-2.7.md
@@ -0,0 +1,16 @@
+# Challenges after upgrade to 3.5 from 2.7
+
+Last year, Qualcomm migrated its largest Gerrit instance from 2.7 to
+3.5. In a previous talk, we discussed our optimizations to schema
+upgrades, NoteDB migration, and offline reindexing. In this talk,
+I’ll delve into the challenges we faced close to the upgrade date and
+after going live. I’ll focus mainly on the issues we encountered with
+our multi-primary setup, repositories on NFS, and JGit, as well as our
+solutions. Also, I’ll explore the performance problems we faced and how
+we overcame them.
+
+I’ll also share some positives, such as what worked well after the
+upgrade, including our use of Elasticsearch as the index backend
+and some updates we made to the Elasticsearch module to meet our needs.
+
+*[Kaushik Lingarkar, Engineer / Qualcomm Technologies, Inc](../speakers.md#kaushikl)*