From c7a2886198b7273165d90d5054e7da669ba97843 Mon Sep 17 00:00:00 2001
From: Andreas Dilger <adilger@whamcloud.com>
Date: Tue, 9 Feb 2021 08:55:39 -0700
Subject: [PATCH] LU-7668 admin: remove OST from config logs

When deactivating an OST permanently, the configuration records can
also be removed from the MGS to avoid the OSC device being configured
on the clients at all using "lctl llog_print" and "lctl llog_cancel".

Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I7d76b092b1ae3fc7abc2759651f246a9b03ebbe5
Reviewed-on: https://review.whamcloud.com/41453
Tested-by: jenkins <devops@whamcloud.com>
---
 LustreMaintenance.xml | 39 +++++++++++++++++++++++++++++++++++----
 1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/LustreMaintenance.xml b/LustreMaintenance.xml
index a9b2c5d..5efcffc 100644
--- a/LustreMaintenance.xml
+++ b/LustreMaintenance.xml
@@ -625,14 +625,45 @@ client$ lfs getstripe --mdt-index /mnt/lustre/local_dir0
             </listitem>
             <listitem>
               <para>If there is not expected to be a replacement for this OST in
-              the near future, permanently deactivate it on all clients and
-	      the MDS by running the following command on the MGS:
-              <screen>mgs# lctl conf_param <replaceable>ost_name</replaceable>.osc.active=0</screen></para>
+                the near future, permanently deactivate it on all clients and
+	        the MDS by running the following command on the MGS:
+                <screen>mgs# lctl conf_param <replaceable>ost_name</replaceable>.osc.active=0</screen></para>
               <note><para>A deactivated OST still appears in the file system
-                configuration, though a replacement OST can be created using the
+                configuration, though a replacement OST can be created that
+                re-uses the same OST index with the
                 <literal>mkfs.lustre --replace</literal> option, see
                 <xref linkend="lustremaint.restore_ost"/>.
               </para></note>
+              <para>To totally remove the OST from the filesystem configuration,
+                the OST configuration records should be found in the startup
+                logs by running the command
+                "<literal>lctl --device MGS llog_print <replaceable>fsname</replaceable>-client</literal>"
+                on the MGS (and also
+                "<literal>... <replaceable>$fsname</replaceable>-MDT<replaceable>xxxx</replaceable></literal>"
+                for all the MDTs) to list all <literal>attach</literal>,
+                <literal>setup</literal>, <literal>add_osc</literal>,
+                <literal>add_pool</literal>, and other records related to the
+                removed OST(s).  Once the <literal>index</literal> value is
+                known for each configuration record, the command
+                "<literal>lctl --device MGS llog_cancel <replaceable>llog_name</replaceable> -i <replaceable>index</replaceable> </literal>"
+                will drop that record from the configuration log
+                <replaceable>llog_name</replaceable> for each of the
+                <literal><replaceable>fsname</replaceable>-client</literal> and
+                <literal><replaceable>fsname</replaceable>-MDTxxxx</literal>
+                configuration logs so that new mounts will no longer process it.
+                If a whole OSS is being removed, the<literal>add_uuid</literal>
+                records for the OSS should similarly be canceled.
+                <screen>
+mgs# lctl --device MGS llog_print testfs-client | egrep "192.168.10.99@tcp|OST0003"
+- { index: 135, event: add_uuid, nid: 192.168.10.99@tcp(0x20000c0a80a63), node: 192.168.10.99@tcp }
+- { index: 136, event: attach, device: testfs-OST0003-osc, type: osc, UUID: testfs-clilov_UUID }
+- { index: 137, event: setup, device: testfs-OST0003-osc, UUID: testfs-OST0003_UUID, node: 192.168.10.99@tcp }
+- { index: 138, event: add_osc, device: testfs-clilov, ost: testfs-OST0003_UUID, index: 3, gen: 1 }
+mgs# lctl --device MGS llog_cancel testfs-client -i 138
+mgs# lctl --device MGS llog_cancel testfs-client -i 137
+mgs# lctl --device MGS llog_cancel testfs-client -i 136
+                </screen>
+              </para>
             </listitem>
           </orderedlist>
         </listitem>
-- 
1.8.3.1