From 76608a503484d096c653b7d093ba4988ee42022c Mon Sep 17 00:00:00 2001
From: Junwei Deng <35031544+TheaperDeng@users.noreply.github.com>
Date: Mon, 27 Jun 2022 11:10:24 +0800
Subject: [PATCH] Orca: add dashboard.log error in known issue (#4943)

* add dashboard.log error

* add title

* typo fix
---
 .../source/doc/Orca/Overview/known_issues.md  | 22 ++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/docs/readthedocs/source/doc/Orca/Overview/known_issues.md b/docs/readthedocs/source/doc/Orca/Overview/known_issues.md
index c6d82120..c7454f02 100644
--- a/docs/readthedocs/source/doc/Orca/Overview/known_issues.md
+++ b/docs/readthedocs/source/doc/Orca/Overview/known_issues.md
@@ -18,4 +18,24 @@ You could follow below steps:
    If you are using `init_orca_context(cluster_mode="spark-submit")`:
    ```
    spark-submit --conf "spark.executorEnv.ARROW_LIBHDFS_DIR=/opt/cloudera/parcels/CDH-5.15.2-1.cdh5.15.2.p0.3/lib64"
-   ```
\ No newline at end of file
+   ```
+
+## **Orca Context Issues**
+
+### **Exception: Failed to read dashbord log: [Errno 2] No such file or directory: '/tmp/ray/.../dashboard.log'**
+
+This error occurs when initialize an orca context with `init_ray_on_spark=True`. We have not locate the root cause of this problem, but it might be caused by an atypical python environment.
+
+You could follow below steps to workaround:
+
+1. If you only need to use functions in ray (e.g. `bigdl.orca.learn` with `backend="ray"`, `bigdl.orca.automl` for pytorch/tensorflow model, `bigdl.chronos.autots` for time series model's auto-tunning), we may use ray as the first-class.
+
+   1. Start a ray cluster by `ray start --head`. if you already have a ray cluster started, please direcetly jump to step 2.
+   2. Initialize an orca context with `runtime="ray"` and `init_ray_on_spark=False`, please refer to detailed information [here](./orca-context.html).
+   3. If you are using `bigdl.orca.automl` or `bigdl.chronos.autots` on a single node, please set:
+      ```python
+      ray_ctx = OrcaContext.get_ray_context()
+      ray_ctx.is_local=True
+      ```
+
+2. If you really need to use ray on spark, please install bigdl-orca under a conda environment. Detailed information please refer to [here](./orca.html).
\ No newline at end of file