From 7a711b5733e1ea6b913e0d2e1ef322e7c69149a6 Mon Sep 17 00:00:00 2001
From: Ian Kelling <iank@fsf.org>
Date: Thu, 1 May 2025 21:27:27 -0400
Subject: [PATCH] improvements based on experience of a bunch of disk
 migrations

---
 .../files/simple/usr/local/bin/create-vm      | 15 +++---
 .../files/simple/usr/local/bin/vm-disk        | 48 +++++++++++--------
 2 files changed, 37 insertions(+), 26 deletions(-)

diff --git a/roles/kvmhost/files/simple/usr/local/bin/create-vm b/roles/kvmhost/files/simple/usr/local/bin/create-vm
index 2c3fa8d..25a7612 100755
--- a/roles/kvmhost/files/simple/usr/local/bin/create-vm
+++ b/roles/kvmhost/files/simple/usr/local/bin/create-vm
@@ -94,7 +94,9 @@ On vm hosts with local storage, disks are grouped into sets of 3 disks, in which
 per-vm raid arrays are created by creating lvm logical volumes and then
 creating an mdadm or btrfs array. While the disks themselves are not
 technically a single raid array, that is their functional purpose so we
-call them each an array.
+call them each an array. The default is btrfs. Please consider it a rule
+to avoid creating nested btrfs subvolumes. We've never seen a good
+reason to do it, but it can create difficulties.
 
 If there is more than one array on a single machine, we need to specify
 which one to use by passing the name of one its VG members with
@@ -127,7 +129,8 @@ to undo what it has done. Be sure to read the output!
 -m --mdraid :     Create an ext4 filesystem on mdraid. We force this
                            option on hosts older than t11. WARNING: this
                            could take an hour or more for a big disk, run
-                           in screen or tmux.
+                           in screen or tmux. TODO: figure this out for
+                           savannah-virsh.
 
 
 Example: $0 www.gnu.org 5000 512 2 flidas
@@ -632,10 +635,10 @@ EOF
   # volume group names, separated by command at the start.
   disk_arrays=(
     ,
-    # community0p 3.46t rust disks as of 2024-09-07
-    vgata-WDC_WD4004FZWX-00GBGB0_NHG3PK4M
-    vgata-ST4000DM000-1F2168_Z3028BKA
-    vgata-WDC_WD40EZRX-00SPEB0_WD-WCC4E0304017
+    # community0p 20t rust disks as of 2025-05-01
+    vgata-TOSHIBA_MG10AFA22TE_9430A1FLFM8J
+    vgata-TOSHIBA_MG10AFA22TE_9440A01ZFM8J
+    vgata-TOSHIBA_MG10AFA22TE_9440A022FM8J
     ,
     # community0p 925g as of 2024-09-07
     vgata-Samsung_SSD_850_EVO_1TB_S3PJNB0J902536K
diff --git a/roles/kvmhost/files/simple/usr/local/bin/vm-disk b/roles/kvmhost/files/simple/usr/local/bin/vm-disk
index 4c86da4..8172cb8 100755
--- a/roles/kvmhost/files/simple/usr/local/bin/vm-disk
+++ b/roles/kvmhost/files/simple/usr/local/bin/vm-disk
@@ -22,7 +22,7 @@ usage() {
   cat <<EOF
 Usage:
 ${0##*/} attach VM VM_DEV_PATH TARGET_VM
-${0##*/} delete VM VM_DEV_PATH...
+${0##*/} detach|delete VM VM_DEV_PATH...
 ${0##*/} list VM
 
 In the 1st form, make VM_DEV_PATH be ALSO attached to
@@ -31,8 +31,11 @@ writes. detach-disk or unsafe-remove-vm should be run within the same
 day as this command. If both VMs are set to autostart, VM will have
 autostart disabled and a large warning printed.
 
-In the 2nd form, delete VM_DEV_PATH... and detach them from the
-VM. The source dev paths should include all members of any raid arrays.
+In the 2nd form, detach or delete (after detaching) VM_DEV_PATH... from the
+VM.
+ * Be careful not to detach a disk from the only VM it is attached to, or fsf sysadmins will have to delete it.
+ * Be careful not to delete a disk that is attached to multiple VMs. It might not work and might require fsf sysadmins to fix.
+ * The source dev paths should include all members of any raid arrays.
 
 In the 3rd form, list the device paths currently attached to
 VM. If run over ssh, this requires running with -t to allocate a pty so
@@ -134,7 +137,7 @@ case $subcmd in
       exit 1
     fi
     ;;
-  delete)
+  delete|detach)
     declare -a devpaths rbdnames all_disks
     for disk; do
       all_disks+=("$disk")
@@ -218,28 +221,17 @@ WARNING: disabled autostart for $source_vm !!!!!!!!!!!!!"
   exit 0
 fi
 
-# Otherwise, we are deleting.
+# otherwise we are deleting or detaching
 
-if ! tty -s; then
+for disk in "${all_disks[@]}"; do check-source-dev; done
+
+if [[ $subcmd == delete ]] && ! tty -s; then
   echo "$0: error, no tty. Use ssh -t." >&2
   exit 1
 fi
 
 
-for disk in "${all_disks[@]}"; do check-source-dev; done
-
 
-### fancy filename for our generated script, eg: 2025-03-19-001
-mkdir -p /root/vm-disk-generated
-date_stamp=$(date +%F)
-for (( i=0; i < 999; i++ )); do
-  script_gen="/root/vm-disk-generated/$date_stamp-$(printf %03d $i)"
-  if [[ ! -s $script_gen ]]; then
-    break
-  fi
-done
-
-initialize-script-gen
 
 target_dev_regex='^[a-z]+$'
 for disk in "${all_disks[@]}"; do
@@ -262,9 +254,25 @@ for disk in "${all_disks[@]}"; do
     exit 1
   fi
 
-  m virsh detach-disk "$source_vm" "$target_dev" --persistent
+  virsh detach-disk "$source_vm" "$target_dev" --persistent
 done
 
+if [[ $subcmd == detach ]]; then
+  exit 0
+fi
+
+### fancy filename for our generated script, eg: 2025-03-19-001
+mkdir -p /root/vm-disk-generated
+date_stamp=$(date +%F)
+for (( i=0; i < 999; i++ )); do
+  script_gen="/root/vm-disk-generated/$date_stamp-$(printf %03d $i)"
+  if [[ ! -s $script_gen ]]; then
+    break
+  fi
+done
+
+initialize-script-gen
+
 vm-disk-wipe
 
 
-- 
2.25.1