From 1513fe1c6cb4fc562b7d260a5d1556a3f2f8dc50 Mon Sep 17 00:00:00 2001
From: DavidCroftDKFZ <46788708+DavidCroftDKFZ@users.noreply.github.com>
Date: Thu, 22 May 2025 18:01:43 +0200
Subject: [PATCH] Added section relating to clearing data from Blaze (#303)

---
 README.md | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/README.md b/README.md
index 0e8131a..6c3cd6d 100644
--- a/README.md
+++ b/README.md
@@ -340,6 +340,24 @@ The storage space on your hard drive will depend on the number of FHIR resources
 
 For more information on Blaze performance, please refer to [import performance](https://github.com/samply/blaze/blob/master/docs/performance/import.md).
 
+### Clearing data
+
+The Bridgehead's FHIR store, Blaze, saves its data in a Docker volume. This means that the data will persist even if you stop the Bridgehead. You can clear existing data from the FHIR store by deleting the relevant Docker volume.
+
+First, stop the Bridgehead:
+```shell
+sudo systemctl stop bridgehead@<PROJECT>.service
+```
+Now remove the volume:
+```shell
+docker volume rm <PROJECT>_blaze-data
+```
+Finally, restart the Bridgehead:
+```shell
+sudo systemctl start bridgehead@<PROJECT>.service
+```
+You will need to do this for example if you are using a VM as a test environment and you subsequently want to use the same VM for production.
+
 #### ETL for BBMRI and GBA
 
 Normally, you will need to build your own ETL to feed the Bridgehead. However, there is one case where a short cut might be available: