Add section about download failures
@@ -96,6 +96,24 @@ Here are some examples. ::
opt/spack/cray-sles15-zen2/gcc-11.2.0/hdf5-1.8.22-c3djozhlmrvy7wpu46f36qeakemiactw
opt/spack/cray-sles15-zen2/gcc-11.2.0/cmake-3.14.7-nnahgnkkl2d2ty2us46we75pnjepci35
+Working around recurring download failures
+------------------------------------------
+
+Depending on context, recurring issues downloading a particular *dependent* package may arise.
+When this happens, SSL certificate handling may be the cause.
+A quick work-around is to disable this `security checking feature <https://spack.readthedocs.io/en/latest/config_yaml.html?highlight=ssl%20certificates#verify-ssl>`_ in Spack by adding the ``--insecure`` command-line option as the second option *just* after ``spack``.
+Alternatively, you may be able to manually download the needed files and place them in a directory for Spack to use as a `mirror <https://spack.readthedocs.io/en/latest/mirrors.html?highlight=mirror#mirrors-mirrors-yaml>`_.
+For example, starting from the point of having successfully downloaded the ``Python-3.7.13.tgz`` file somewhere, here are the Spack steps... ::
+
+ spack mirror add my_local_mirror file://`pwd`/my_local_mirror
+ mkdir -p my_local_mirror/python
+ cp Python-3.7.13.tgz my_local_mirror/python/python-3.7.13.tgz
+
+Note that change in case of the file name.
+Doing this will cause Spack to go get the file you manually downloaded.
+The first step to add the mirror is only needed once.
+To add additional files for which recurring download failures are occurring, just copy them into the mirror following the Spack naming conventions for packages.
+
The spack environment files
---------------------------
