diff --git a/Admin/components/README b/Admin/components/README
--- a/Admin/components/README
+++ b/Admin/components/README
@@ -1,78 +1,72 @@
 Notes on maintaining the Isabelle component repository at TUM
 =============================================================
 
 Quick reference
 ---------------
 
-  * ensure that Isabelle/Scala/SSH can connect to the host specified via
-    system option `isabelle_components_server`; this may require to install
-    an unencrypted ssh host key as follows:
-
-      $ ssh-keyscan -t rsa lxbroy10.informatik.tu-muenchen.de >> ~/.ssh/known_hosts
-
   * local setup (and test) of component directory, e.g. in
 
       screwdriver-3.14/
 
   * packaging (with associated SHA1 digest), e.g.
 
       $ isabelle build_components screwdriver-3.14
 
   * publishing, e.g.
 
       $ isabelle build_components -P screwdriver-3.14.tar.gz
 
   * manual editing of Admin/components/main: screwdriver-3.14
 
 
 Unique names
 ------------
 
 Component names are globally unique over time and space: names of
 published components are never re-used.  If some component needs to be
 re-packaged, extra indices may be added to the official version number
 like this:
 
   screwdriver-3.14    #default packaging/publishing, no index
   screwdriver-3.14-1  #another refinement of the same
   screwdriver-3.14-2  #yet another refinement of the same
 
 There is no standard format for the structure of component names: they
 are compared for equality only, without any guess at an ordering.
 
 Components are registered in Admin/components/main (or similar) for
 use of that particular Isabelle repository version, subject to regular
 Mercurial history.  This allows to bisect Isabelle versions with full
 record of the required components for testing.
 
 
 Authentic archives
 ------------------
 
 Isabelle components are managed as authentic .tar.gz archives in
 /home/isabelle/components from where they are made publicly available
 on https://isabelle.in.tum.de/components/.
 
 Visibility on the HTTP server depends on local Unix file permission:
 nonfree components should omit "read" mode for the Unix group/other;
 regular components should be world-readable.
 
 The file `Admin/components/components.sha1` contains SHA1 identifiers
 within the Isabelle repository, for integrity checking of the archives
 that are exposed to the public file-system.  The command-line tool
 `isabelle build_components` maintains these hash-keys automatically.
 
 
 Unpacked copy
 -------------
 
 A second unpacked copy is provided in `/home/isabelle/contrib/`. This allows
 users and administrative services within the TUM network to activate arbitrary
 snapshots of the repository with all standard components being available,
 without extra copying or unpacking of the authentic archives. The
 isabelle_cronjob does this routinely: it will break if the unpacked version is
 omitted.
 
 The command-line tool `isabelle build_components -P` takes care of uploading
 the .tar.gz archive and unpacking it, unless it is a special component (e.g.
 for multiplatform application bundling).
diff --git a/Admin/cronjob/README b/Admin/cronjob/README
--- a/Admin/cronjob/README
+++ b/Admin/cronjob/README
@@ -1,59 +1,55 @@
 Administrative Isabelle cronjob
 ===============================
 
 - main server: virtual machine with cronjob and build_log database
 - backup file-system (for cumulative log files): i21isatest@lxbroy10:cronjob
 - backup identify job: i21isatest@lxcisa0
 
 - jobs: manual installation on target directory:
     cp "$ISABELLE_HOME/Admin/cronjob/self_update "$HOME/cronjob/self_update"
     cp "$ISABELLE_HOME/Admin/cronjob/plain_identify "$HOME/cronjob/plain_identify"
 
 - crontab: manual update on target machine
     crontab -l
     crontab -e
 
 - $HOME/cronjob/run/ -- run-time state
 
 - $HOME/cronjob/log/ -- cumulative log area
 
 
 Build Log Database Server
 =========================
 
 - Ubuntu 20.04 LTS Linux Server standard installation
   https://help.ubuntu.com/lts/serverguide
 
 - apt install unattended-upgrades
 
 - special user account:
   useradd -m -s /bin/bash isatest
 
-- SSH access for jsch (on each client):
-  LOCALHOST$ ssh-keyscan -t rsa DBSERVER
-  >> ~/.ssh/known_hosts
-
 - PostgreSQL:
 
   $ apt install postgresql
   $ apt install postgresql-client
 
   $ sudo -u postgres psql template1
   ALTER USER postgres with encrypted password '***';
 
   $ edit /etc/postgresql/10/main/pg_hba.conf
   local all postgres md5
   local all all md5
 
   $ systemctl restart postgresql.service
 
   $ createuser -U postgres --interactive isatest
   ALTER USER isatest with encrypted password '***';
 
   $ createdb -E UTF8 -T template0 --locale=en_US.utf8 -U postgres -O isatest isatest
 
 - Database backup or migration:
   https://www.postgresql.org/docs/9.5/static/backup-dump.html
 
      pg_dump -U postgres -Fc -v -d isatest > db.dump
   pg_restore -U postgres -Fc -v -d isatest < db.dump