diff --git a/xCAT-server/share/xcat/install/scripts/getinstdisk b/xCAT-server/share/xcat/install/scripts/getinstdisk
index bb345a632..64236b2fc 100644
--- a/xCAT-server/share/xcat/install/scripts/getinstdisk
+++ b/xCAT-server/share/xcat/install/scripts/getinstdisk
@@ -38,9 +38,9 @@ if [ -z "$install_disk" ]; then
 
     # Get all partitions and disks from /proc/partitions file
     if [ -z "$has_awk" ]; then
-        entries=$(cat /proc/partitions | sed 's/  */ /g' | cut -d " " -f5 | grep -v "name" | grep -E '^[s|h|v]d|nvme')
+        entries=$(cat /proc/partitions | sed 's/  */ /g' | cut -d " " -f5 | grep -v "name" | grep -E '^(x?v|s|h)d|^nvme')
     else
-        entries=$(awk -F ' '  '{print $4}' /proc/partitions | grep -v "name" | grep -E '^[s|h|v]d|nvme')
+        entries=$(awk -F ' '  '{print $4}' /proc/partitions | grep -v "name" | grep -E '^(x?v|s|h)d|^nvme')
     fi
 
     # Classify entries by DEVTYPE
@@ -156,10 +156,8 @@ if [ -z "$install_disk" ]; then
         rm $file;
     done
 
-    has_wwn=0
-    has_path=0
-    file_pre=""
     disk_data=""
+    disk_rank=""
 
     # Check disks which had installed OS, or check all disks in /proc/partitions
     for disk in $disks; do
@@ -177,59 +175,51 @@ if [ -z "$install_disk" ]; then
         echo "[get_install_disk]    disk_path=$disk_path"
         echo "[get_install_disk]    disk_driver=$disk_driver"
 
-        # Check whether there is WWN, PATH information
+        # Rank the identifier. A disk that reports a WWN sorts ahead of one
+        # that reports only a path, and that one ahead of a disk with neither,
+        # but the rank decides only among disks of the same driver group.
         if [ "$disk_wwn" ]; then
-            has_wwn=1
-            file_pre="wwn"
+            disk_rank="0"
             disk_data=$disk_wwn
-        elif [ $has_wwn -eq 1 ]; then
-            echo "[get_install_disk]    The disk $disk has no wwn info."
-            echo "[get_install_disk]    There is another disk with wwn info, so don't record this disk."
-            continue;
         elif [ "$disk_path" ]; then
-            has_path=1
-            file_pre="path"
+            disk_rank="1"
             disk_data=$disk_path
-        elif [ $has_path -eq 1 ]; then
-            echo "[get_install_disk]    The disk $disk has no wwn or path info."
-            echo "[get_install_disk]    There is another disk with path info, so don't record this disk."
-            continue;
         else
-           file_pre="other"
-           disk_data=""
+            disk_rank="2"
+            disk_data=""
         fi
 
         # Sort disks by DRIVER type
         case "$disk_driver" in
         "ata_piix"*|"ahci")
-            echo "$disk $disk_data" >> "$tmpfile""$file_pre""firstchoicedisks"
-            echo "[get_install_disk]    Add disk: $disk $disk_data into $file_pre firstchoicedisks"
+            echo "$disk $disk_rank$disk_data" >> "$tmpfile""firstchoicedisks"
+            echo "[get_install_disk]    Add disk: $disk $disk_data into firstchoicedisks"
             ;;
         "PMC MaxRAID"|"megaraid_sas")
-            echo "$disk $disk_data" >> "$tmpfile""$file_pre""secondchoicedisks"
-            echo "[get_install_disk]    Add disk: $disk $disk_data into $file_pre secondchoicedisks"
+            echo "$disk $disk_rank$disk_data" >> "$tmpfile""secondchoicedisks"
+            echo "[get_install_disk]    Add disk: $disk $disk_data into secondchoicedisks"
             ;;
         "mptsas"|"mpt2sas"|"mpt3sas")
-            echo "$disk $disk_data" >> "$tmpfile""$file_pre""thirdchoicedisks"
-            echo "[get_install_disk]    Add disk: $disk $disk_data into $file_pre thirdchoicedisks"
+            echo "$disk $disk_rank$disk_data" >> "$tmpfile""thirdchoicedisks"
+            echo "[get_install_disk]    Add disk: $disk $disk_data into thirdchoicedisks"
             ;;
         *)
-            echo "$disk $disk_data" >> "$tmpfile""$file_pre""fourthchoicedisks"
-            echo "[get_install_disk]    Add disk: $disk $disk_data into $file_pre fourthchoicedisks"
+            echo "$disk $disk_rank$disk_data" >> "$tmpfile""fourthchoicedisks"
+            echo "[get_install_disk]    Add disk: $disk $disk_data into fourthchoicedisks"
             ;;
         esac
     done
 
     for seq in first second third fourth; do
-        if [ -s $tmpfile$file_pre${seq}choicedisks ]; then
-            install_file="$tmpfile$file_pre${seq}choicedisks"
+        if [ -s $tmpfile${seq}choicedisks ]; then
+            install_file="$tmpfile${seq}choicedisks"
             break
         fi
     done
 
     if [ "$install_file" ] && [ -s $install_file ]; then
         install_disk=/dev/$(cat $install_file | grep -v "^$" | sort -k 2 -b | cut -d " " -f1 | head -n 1)
-        echo "[get_install_disk]The install_disk is $install_disk by sorting $file_pre and DRIVER."
+        echo "[get_install_disk]The install_disk is $install_disk by DRIVER, then by identifier."
     fi
 
     for file in $tmpfile*; do
diff --git a/xCAT-test/autotest/testcase/get_install_disk/fresh_install_disk b/xCAT-test/autotest/testcase/get_install_disk/fresh_install_disk
index c75af50c8..8d7756a5e 100644
--- a/xCAT-test/autotest/testcase/get_install_disk/fresh_install_disk
+++ b/xCAT-test/autotest/testcase/get_install_disk/fresh_install_disk
@@ -56,11 +56,11 @@ check:output=~0x500a0751036d9e61
 check:output=~0x500a0751036d9e83
 check:output=~0x500a0751036d9e7a
 check:output=~0x500a0751036d9c24
-cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "into wwn thirdchoicedisks"
+cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "into thirdchoicedisks"
 check:output=~sda 0x500a0751036d9e61
 check:output=~sdb 0x500a0751036d9c24
 check:output=~sdc 0x500a0751036d9e7a
 check:output=~sdd 0x500a0751036d9e83
-cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "by sorting wwn and DRIVER"
+cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "by DRIVER, then by identifier"
 check:output=~sdb
 end
diff --git a/xCAT-test/autotest/testcase/get_install_disk/reinstall_disk b/xCAT-test/autotest/testcase/get_install_disk/reinstall_disk
index 8e096114f..dc3b3b396 100644
--- a/xCAT-test/autotest/testcase/get_install_disk/reinstall_disk
+++ b/xCAT-test/autotest/testcase/get_install_disk/reinstall_disk
@@ -35,7 +35,7 @@ check:rc==0
 check:output=~booted
 
 cmd:xdsh $$CN "scp /var/log/xcat/xcat.log root@$$MN:/tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_before_re_$$NO"
-cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "by sorting wwn and DRIVER"
+cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "by DRIVER, then by identifier"
 check:output=~sdb
 
 cmd:chdef $$CN status=
@@ -72,9 +72,9 @@ cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "
 check:output=~The disk sdb information
 cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "disk_wwn="
 check:output=~0x500a0751036d9c24
-cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "into wwn"
-check:output=~sdb 0x500a0751036d9c24 into wwn
-cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "by sorting wwn and DRIVER"
+cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "0x500a0751036d9c24 into"
+check:output=~sdb 0x500a0751036d9c24 into
+cmd:cat /tmp/__GETNODEATTR($$CN,os)__-__GETNODEATTR($$CN,arch)__fr_$$NO | grep "by DRIVER, then by identifier"
 check:output=~sdb
 
 end
diff --git a/xCAT-test/unit/getinstdisk_selection.t b/xCAT-test/unit/getinstdisk_selection.t
index cb4dfa55d..00f040548 100644
--- a/xCAT-test/unit/getinstdisk_selection.t
+++ b/xCAT-test/unit/getinstdisk_selection.t
@@ -55,6 +55,7 @@ sub run_scenario {
         my %attr = %{ $disk{$name} };
         open( my $props, '>', "$fixdir/$name.props" ) or die $!;
         print $props "ID_WWN=$attr{wwn}\n" if $attr{wwn};
+        print $props "DEVPATH=$attr{path}\n" if $attr{path};
         print $props "DEVTYPE=disk\n";
         close($props);
         open( my $attrs, '>', "$fixdir/$name.attrs" ) or die $!;
@@ -130,6 +131,40 @@ selects( '/dev/nvme0n1', 'an NVMe device is selected from the last group',
 # No usable disk falls back to the documented default.
 selects( '/dev/sda', 'no disks fall back to the default' );
 
+# The driver group decides before the identifier. A disk that reports no WWN
+# used to be dropped when another disk reported one, or to be ignored because
+# the readback only opened the files of the last identifier class seen.
+selects( '/dev/sdb', 'the direct attached disk wins when only the RAID volume reports a WWN',
+    sda => { driver => 'megaraid_sas', wwn => '0x5000cca0aaaa0001' },
+    sdb => { driver => 'ahci' } );
+
+selects( '/dev/sda', 'the direct attached disk wins when it is scanned first without a WWN',
+    sda => { driver => 'ahci' },
+    sdb => { driver => 'megaraid_sas', wwn => '0x5000cca0aaaa0002' } );
+
+# Within one driver group the identifier decides, and a disk that reports one
+# is preferred, because that name is stable across reboots.
+selects( '/dev/sdb', 'the disk with a WWN wins inside the group',
+    sda => { driver => 'ahci' },
+    sdb => { driver => 'ahci', wwn => '0x5000cca0bbbb0001' } );
+
+selects( '/dev/sdb', 'the lower WWN wins inside the group',
+    sda => { driver => 'ahci', wwn => '0x5000cca0bbbb0002' },
+    sdb => { driver => 'ahci', wwn => '0x5000cca0bbbb0001' } );
+
+selects( '/dev/sda', 'a path is preferred over no identifier at all',
+    sda => { driver => 'ahci', path => '/devices/pci0000:00/0000:00:1f.2/ata1/host0/target0:0:0/0:0:0:0/block/sda' },
+    sdb => { driver => 'ahci' } );
+
+# A Xen guest presents xvd names. The scan has to see them, because the
+# fallback below it would take the first one without looking.
+selects( '/dev/xvda', 'a Xen disk is scanned rather than assumed',
+    xvda => { driver => 'vbd' } );
+
+selects( '/dev/xvdb', 'the better driver group wins among Xen disks',
+    xvda => { driver => 'vbd' },
+    xvdb => { driver => 'ahci' } );
+
 # Every installer includes the one script, which carries the fallbacks and the
 # logging that the separate RHEL 10 copy used to hold on its own.
 my $common = slurp( $scripts[0] );