Détecter un nouveau disque ou LUN sur un système Linux (rescan bus)

Pour détecter un nouveau disque, ou tout changement de taille d’un LUN ou d’un disque sur Linux, il faut envoyer le texte “- – -” dans un fichier texte ce qui initiera le scan. Le problème est que cette opération n’enlève pas les dsique supprimés par exemple, et ne permet pas de scanner tous les contrôleurs en une fois, mais un à un. Donc à condition de savoir comment identifier le bus que l’on souhaite scanner, il faudra tous les faire.

L’alternative est cet excellent script de Kurt Garloff et Hannes Reinecke, distribuable sous license GNU GPL v2
#!/bin/bash
# Skript to rescan SCSI bus, using the
# scsi add-single-device mechanism
# (c) 1998--2008 Kurt Garloff , GNU GPL v2 or later
# (c) 2006--2008 Hannes Reinecke, GNU GPL v2 or later
# $Id: rescan-scsi-bus.sh,v 1.48 2010/08/10 19:32:22 garloff Exp $

setcolor ()
{
  red="\e[0;31m"
  green="\e[0;32m"
  yellow="\e[0;33m"
  bold="\e[0;1m"
  norm="\e[0;0m"
}

unsetcolor ()
{
  red=""; green=""
  yellow=""; norm=""
}

# Output some text and return cursor to previous position
# (only works for simple strings)
# Stores length of string in LN and returns it
print_and_scroll_back ()
{
  STRG="$1"
  LN=${#STRG}
  BK=""
  declare -i cntr=0
  while test $cntr -lt $LN; do BK="$BK\e[D"; let cntr+=1; done
  echo -en "$STRG$BK"
  return $LN
}

# Overwrite a text of length $1 (fallback to $LN) with whitespace
white_out ()
{
  BK=""; WH=""
  if test -n "$1"; then LN=$1; fi
  declare -i cntr=0
  while test $cntr -lt $LN; do BK="$BK\e[D"; WH="$WH "; let cntr+=1; done
  echo -en "$WH$BK"
}

# Return hosts. sysfs must be mounted
findhosts_26 ()
{
  hosts=
  for hostdir in /sys/class/scsi_host/host*; do
    hostno=${hostdir#/sys/class/scsi_host/host}
    if [ -f $hostdir/isp_name ] ; then
      hostname="qla2xxx"
    elif [ -f $hostdir/lpfc_drvr_version ] ; then
      hostname="lpfc"
    else
      hostname=`cat $hostdir/proc_name`
    fi
    hosts="$hosts $hostno"
    echo "Host adapter $hostno ($hostname) found."
  done
  if [ -z "$hosts" ] ; then
    echo "No SCSI host adapters found in sysfs"
    exit 1;
  fi
  hosts=`echo $hosts | sed 's/ /\n/g' | sort -n`
}

# Return hosts. /proc/scsi/HOSTADAPTER/? must exist
findhosts ()
{
  hosts=
  for driverdir in /proc/scsi/*; do
    driver=${driverdir#/proc/scsi/}
    if test $driver = scsi -o $driver = sg -o $driver = dummy -o $driver = device_info; then continue; fi
    for hostdir in $driverdir/*; do
      name=${hostdir#/proc/scsi/*/}
      if test $name = add_map -o $name = map -o $name = mod_parm; then continue; fi
      num=$name
      driverinfo=$driver
      if test -r $hostdir/status; then
        num=$(printf '%d\n' `sed -n 's/SCSI host number://p' $hostdir/status`)
        driverinfo="$driver:$name"
      fi
      hosts="$hosts $num"
      echo "Host adapter $num ($driverinfo) found."
    done
  done
}

printtype ()
{
  local type=$1

  case "$type" in
    0) echo "Direct-Access    " ;;
    1) echo "Sequential-Access" ;;
    2) echo "Printer          " ;;
    3) echo "Processor        " ;;
    4) echo "WORM             " ;;
    5) echo "CD-ROM           " ;;
    6) echo "Scanner          " ;;
    7) echo "Optical Device   " ;;
    8) echo "Medium Changer   " ;;
    9) echo "Communications   " ;;
    10) echo "Unknown          " ;;
    11) echo "Unknown          " ;;
    12) echo "RAID             " ;;
    13) echo "Enclosure        " ;;
    14) echo "Direct-Access-RBC" ;;
    *) echo "Unknown          " ;;
  esac
}

print02i()
{
    if [ "$1" = "*" ] ; then
        echo "00"
    else
        printf "%02i" "$1"
    fi
}

# Get /proc/scsi/scsi info for device $host:$channel:$id:$lun
# Optional parameter: Number of lines after first (default = 2),
# result in SCSISTR, return code 1 means empty.
procscsiscsi ()
{
  if test -z "$1"; then LN=2; else LN=$1; fi
  CHANNEL=`print02i "$channel"`
  ID=`print02i "$id"`
  LUN=`print02i "$lun"`
  if [ -d /sys/class/scsi_device ]; then
    SCSIPATH="/sys/class/scsi_device/${host}:${channel}:${id}:${lun}"
    if [ -d  "$SCSIPATH" ] ; then
      SCSISTR="Host: scsi${host} Channel: $CHANNEL Id: $ID Lun: $LUN"
      if [ "$LN" -gt 0 ] ; then
        IVEND=$(cat ${SCSIPATH}/device/vendor)
        IPROD=$(cat ${SCSIPATH}/device/model)
        IPREV=$(cat ${SCSIPATH}/device/rev)
        SCSIDEV=$(printf '  Vendor: %-08s Model: %-16s Rev: %-4s' "$IVEND" "$IPROD" "$IPREV")
        SCSISTR="$SCSISTR
$SCSIDEV"
      fi
      if [ "$LN" -gt 1 ] ; then
        ILVL=$(cat ${SCSIPATH}/device/scsi_level)
        type=$(cat ${SCSIPATH}/device/type)
        ITYPE=$(printtype $type)
        SCSITMP=$(printf '  Type:   %-16s                ANSI SCSI revision: %02d' "$ITYPE" "$((ILVL - 1))")
        SCSISTR="$SCSISTR
$SCSITMP"
      fi
    else
      return 1
    fi
  else
    grepstr="scsi$host Channel: $CHANNEL Id: $ID Lun: $LUN"
    SCSISTR=`cat /proc/scsi/scsi | grep -A$LN -e"$grepstr"`
  fi
  if test -z "$SCSISTR"; then return 1; else return 0; fi
}

# Find sg device with 2.6 sysfs support
sgdevice26 ()
{
  if test -e /sys/class/scsi_device/$host\:$channel\:$id\:$lun/device/generic; then
    SGDEV=`readlink /sys/class/scsi_device/$host\:$channel\:$id\:$lun/device/generic`
    SGDEV=`basename $SGDEV`
  else
    for SGDEV in /sys/class/scsi_generic/sg*; do
      DEV=`readlink $SGDEV/device`
      if test "${DEV##*/}" = "$host:$channel:$id:$lun"; then
        SGDEV=`basename $SGDEV`; return
      fi
    done
    SGDEV=""
  fi
}

# Find sg device with 2.4 report-devs extensions
sgdevice24 ()
{
  if procscsiscsi 3; then
    SGDEV=`echo "$SCSISTR" | grep 'Attached drivers:' | sed 's/^ *Attached drivers: \(sg[0-9]*\).*/\1/'`
  fi
}

# Find sg device that belongs to SCSI device $host $channel $id $lun
# and return in SGDEV
sgdevice ()
{
  SGDEV=
  if test -d /sys/class/scsi_device; then
    sgdevice26
  else
    DRV=`grep 'Attached drivers:' /proc/scsi/scsi 2>/dev/null`
    repdevstat=$((1-$?))
    if [ $repdevstat = 0 ]; then
      echo "scsi report-devs 1" >/proc/scsi/scsi
      DRV=`grep 'Attached drivers:' /proc/scsi/scsi 2>/dev/null`
      if [ $? = 1 ]; then return; fi
    fi
    if ! `echo $DRV | grep 'drivers: sg' >/dev/null`; then
      modprobe sg
    fi
    sgdevice24
    if [ $repdevstat = 0 ]; then
      echo "scsi report-devs 0" >/proc/scsi/scsi
    fi
  fi
}

# Test if SCSI device is still responding to commands
testonline ()
{
  : testonline
  RC=0
  if test ! -x /usr/bin/sg_turs; then return 0; fi
  sgdevice
  if test -z "$SGDEV"; then return 0; fi
  sg_turs /dev/$SGDEV >/dev/null 2>&1
  RC=$?
  # Handle in progress of becoming ready and unit attention -- wait at max 11s
  declare -i ctr=0
  if test $RC = 2 -o $RC = 6; then
    RMB=`sg_inq /dev/$SGDEV | grep 'RMB=' | sed 's/^.*RMB=\(.\).*$/\1/'`
    print_and_scroll_back "$host:$channel:$id:$lun $SGDEV ($RMB) "
  fi
  while test $RC = 2 -o $RC = 6 && test $ctr -le 8; do
    if test $RC = 2 -a "$RMB" != "1"; then echo -n "."; let $LN+=1; sleep 1
    else usleep 20000; fi
    let ctr+=1
    sg_turs /dev/$SGDEV >/dev/null 2>&1
    RC=$?
  done
  if test $ctr != 0; then white_out; fi
  # echo -e "\e[A\e[A\e[A${yellow}Test existence of $SGDEV = $RC ${norm} \n\n\n"
  if test $RC = 1; then return $RC; fi
  # Reset RC (might be !=0 for passive paths)
  RC=0
  # OK, device online, compare INQUIRY string
  INQ=`sg_inq $sg_len_arg /dev/$SGDEV 2>/dev/null`
  IVEND=`echo "$INQ" | grep 'Vendor identification:' | sed 's/^[^:]*: \(.*\)$/\1/'`
  IPROD=`echo "$INQ" | grep 'Product identification:' | sed 's/^[^:]*: \(.*\)$/\1/'`
  IPREV=`echo "$INQ" | grep 'Product revision level:' | sed 's/^[^:]*: \(.*\)$/\1/'`
  STR=`printf "  Vendor: %-08s Model: %-16s Rev: %-4s" "$IVEND" "$IPROD" "$IPREV"`
  IPTYPE=`echo "$INQ" | sed -n 's/.* Device_type=\([0-9]*\) .*/\1/p'`
  IPQUAL=`echo "$INQ" | sed -n 's/ *PQual=\([0-9]*\)  Device.*/\1/p'`
  if [ "$IPQUAL" != 0 ] ; then
    echo -e "\e[A\e[A\e[A\e[A${red}$SGDEV changed: ${bold}LU not available (PQual $IPQUAL)${norm}    \n\n\n"
    return 2
  fi

  TYPE=$(printtype $IPTYPE)
  procscsiscsi
  TMPSTR=`echo "$SCSISTR" | grep 'Vendor:'`
  if [ "$TMPSTR" != "$STR" ]; then
    echo -e "\e[A\e[A\e[A\e[A${red}$SGDEV changed: ${bold}\nfrom:${SCSISTR#* } \nto: $STR ${norm} \n\n\n"
    return 1
  fi
  TMPSTR=`echo "$SCSISTR" | sed -n 's/.*Type: *\(.*\) *ANSI.*/\1/p'`
  if [ $TMPSTR != $TYPE ] ; then
    echo -e "\e[A\e[A\e[A\e[A${red}$SGDEV changed: ${bold}\nfrom:${TMPSTR} \nto: $TYPE ${norm} \n\n\n"
    return 1
  fi
  return $RC
}

# Test if SCSI device $host $channen $id $lun exists
# Outputs description from /proc/scsi/scsi (unless arg passed)
# Returns SCSISTR (empty if no dev)
testexist ()
{
  : testexist
  SCSISTR=
  if procscsiscsi && test -z "$1"; then
    echo "$SCSISTR" | head -n1
    echo "$SCSISTR" | tail -n2 | pr -o4 -l1
  fi
}

# Returns the list of existing channels per host
chanlist ()
{
  local hcil
  local cil
  local chan
  local tmpchan

  for dev in /sys/class/scsi_device/${host}:* ; do
    [ -d $dev ] || continue;
    hcil=${dev##*/}
    cil=${hcil#*:}
    chan=${cil%%:*}
    for tmpchan in $channelsearch ; do
      if test "$chan" -eq $tmpchan ; then
        chan=
      fi
    done
    if test -n "$chan" ; then
      channelsearch="$channelsearch $chan"
    fi
  done
  if test -z "$channelsearch"; then channelsearch="0"; fi
}

# Returns the list of existing targets per host
idlist ()
{
  local hcil
  local cil
  local il
  local target
  local tmpid

  for dev in /sys/class/scsi_device/${host}:${channel}:* ; do
    [ -d $dev ] || continue;
    hcil=${dev##*/}
    cil=${hcil#*:}
    il=${cil#*:}
    target=${il%%:*}
    for tmpid in $idsearch ; do
      if test "$target" -eq $tmpid ; then
        target=
        break
      fi
    done
    if test -n "$target" ; then
      idsearch="$idsearch $target"
    fi
  done
}

# Returns the list of existing LUNs from device $host $channel $id $lun
# and returns list to stdout
getluns()
{
  sgdevice
  if test -z "$SGDEV"; then return; fi
  if test ! -x /usr/bin/sg_luns; then echo 0; return; fi
  LLUN=`sg_luns -d /dev/$SGDEV 2>/dev/null`
  if test $? != 0; then echo 0; return; fi
  echo "$LLUN" | sed -n 's/.*lun=\(.*\)/\1/p'
}

# Wait for udev to settle (create device nodes etc.)
udevadm_settle()
{
  if test -x /sbin/udevadm; then
    print_and_scroll_back " Calling udevadm settle (can take a while) "
    /sbin/udevadm settle
    white_out
  else
    usleep 20000
  fi
}

# Perform scan on a single lun $host $channel $id $lun
dolunscan()
{
  SCSISTR=
  devnr="$host $channel $id $lun"
  echo "Scanning for device $devnr ... "
  printf "${yellow}OLD: $norm"
  testexist
  # Special case: lun 0 just got added (for reportlunscan),
  # so make sure we correctly treat it as new
  if test "$lun" = "0" -a "$1"; then
    SCSISTR=""
    printf "\r\e[A\e[A\e[A"
  fi
  : f $remove s $SCSISTR
  if test "$remove" -a "$SCSISTR"; then
    # Device exists: Test whether it's still online
    # (testonline returns 1 if it's gone or has changed)
    testonline
    RC=$?
    if test $RC != 0 -o ! -z "$forceremove"; then
      echo -en "\r\e[A\e[A\e[A${red}REM: "
      echo "$SCSISTR" | head -n1
      echo -e "${norm}\e[B\e[B"
      if test -e /sys/class/scsi_device/${host}:${channel}:${id}:${lun}/device; then
        echo 1 > /sys/class/scsi_device/${host}:${channel}:${id}:${lun}/device/delete
        if test $RC -eq 1 -o $lun -eq 0 ; then
          # Try readding, should fail if device is gone
          echo "$channel $id $lun" > /sys/class/scsi_host/host${host}/scan
        fi
        # FIXME: Can we skip udevadm settle for removal?
        #udevadm_settle
        usleep 20000
      else
        echo "scsi remove-single-device $devnr" > /proc/scsi/scsi
        if test $RC -eq 1 -o $lun -eq 0 ; then
          # Try readding, should fail if device is gone
          echo "scsi add-single-device $devnr" > /proc/scsi/scsi
        fi
      fi
    fi
    if test $RC = 0 -o "$forcerescan" ; then
      if test -e /sys/class/scsi_device/${host}:${channel}:${id}:${lun}/device; then
        echo 1 > /sys/class/scsi_device/${host}:${channel}:${id}:${lun}/device/rescan
        udevadm_settle
      fi
    fi
    printf "\r\e[A\e[A\e[A${yellow}OLD: $norm"
    testexist
    if test -z "$SCSISTR"; then
      printf "\r${red}DEL: $norm\r\n\n"
      let rmvd+=1;
      return 1
    fi
  fi
  if test -z "$SCSISTR"; then
    # Device does not exist, try to add
    printf "\r${green}NEW: $norm"
    if test -e /sys/class/scsi_host/host${host}/scan; then
      echo "$channel $id $lun" > /sys/class/scsi_host/host${host}/scan 2> /dev/null
      udevadm_settle
    else
      echo "scsi add-single-device $devnr" > /proc/scsi/scsi
    fi
    testexist
    if test -z "$SCSISTR"; then
      # Device not present
      printf "\r\e[A";
      # Optimization: if lun==0, stop here (only if in non-remove mode)
      if test $lun = 0 -a -z "$remove" -a $optscan = 1; then
        break;
      fi
    else
      let found+=1;
    fi
  fi
}

# Perform report lun scan on $host $channel $id using REPORT_LUNS
doreportlun()
{
  lun=0
  SCSISTR=
  devnr="$host $channel $id $lun"
  echo -en "Scanning for device $devnr ...\r"
  lun0added=
  #printf "${yellow}OLD: $norm"
  # Phase one: If LUN0 does not exist, try to add
  testexist -q
  if test -z "$SCSISTR"; then
    # Device does not exist, try to add
    #printf "\r${green}NEW: $norm"
    if test -e /sys/class/scsi_host/host${host}/scan; then
      echo "$channel $id $lun" > /sys/class/scsi_host/host${host}/scan 2> /dev/null
      udevadm_settle
    else
      echo "scsi add-single-device $devnr" > /proc/scsi/scsi
    fi
    testexist -q
    if test -n "$SCSISTR"; then
      lun0added=1
      #testonline
    else
      # Device not present
      # return
      # Find alternative LUN to send getluns to
      for dev in /sys/class/scsi_device/${host}:${channel}:${id}:*; do
        [ -d "$dev" ] || continue
        lun=${dev##*:}
        break
      done
    fi
  fi
  targetluns=`getluns`
  lunremove=
  #echo "getluns reports " $targetluns
  # Check existing luns
  for dev in /sys/class/scsi_device/${host}:${channel}:${id}:*; do
    [ -d "$dev" ] || continue
    lun=${dev##*:}
    newsearch=
    inlist=
    # OK, is existing $lun (still) in reported list
    for tmplun in $targetluns; do
      if test $tmplun -eq $lun ; then
        inlist=1
        dolunscan $lun0added
      else
        newsearch="$newsearch $tmplun"
      fi
    done
    # OK, we have now done a lunscan on $lun and
    # $newsearch is the old $targetluns without $lun
    if [ -z "$inlist" ]; then
      # Stale lun
      lunremove="$lunremove $lun"
    fi
    # $lun removed from $lunsearch (echo for whitespace cleanup)
    targetluns=`echo $newsearch`
  done
  # Add new ones and check stale ones
  for lun in $targetluns $lunremove; do
    dolunscan $lun0added
  done
}

# Perform search (scan $host)
dosearch ()
{
  if test -z "$channelsearch" ; then
    chanlist
  fi
  for channel in $channelsearch; do
    if test -z "$idsearch" ; then
      idlist
    fi
    for id in $idsearch; do
      if test -z "$lunsearch" ; then
        doreportlun
      else
        for lun in $lunsearch; do
          dolunscan
        done
      fi
    done
  done
}

expandlist ()
{
  list=$1
  result=""
  first=${list%%,*}
  rest=${list#*,}
  while test ! -z "$first"; do
    beg=${first%%-*};
    if test "$beg" = "$first"; then
      result="$result $beg";
    else
      end=${first#*-}
      result="$result `seq $beg $end`"
    fi
    test "$rest" = "$first" && rest=""
    first=${rest%%,*}
    rest=${rest#*,}
  done
  echo $result
}

# main
if test @$1 = @--help -o @$1 = @-h -o @$1 = @-?; then
    echo "Usage: rescan-scsi-bus.sh [options] [host [host ...]]"
    echo "Options:"
    echo " -l      activates scanning for LUNs 0--7   [default: 0]"
    echo " -L NUM  activates scanning for LUNs 0--NUM [default: 0]"
    echo " -w      scan for target device IDs 0--15   [default: 0--7]"
    echo " -c      enables scanning of channels 0 1   [default: 0 / all detected ones]"
    echo " -r      enables removing of devices        [default: disabled]"
    echo " -i      issue a FibreChannel LIP reset     [default: disabled]"
    echo "--remove:        same as -r"
    echo "--issue-lip:     same as -i"
    echo "--forcerescan:   Rescan existing devices"
    echo "--forceremove:   Remove and readd every device (DANGEROUS)"
    echo "--nooptscan:     don't stop looking for LUNs is 0 is not found"
    echo "--color:         use coloured prefixes OLD/NEW/DEL"
    echo "--hosts=LIST:    Scan only host(s) in LIST"
    echo "--channels=LIST: Scan only channel(s) in LIST"
    echo "--ids=LIST:      Scan only target ID(s) in LIST"
    echo "--luns=LIST:     Scan only lun(s) in LIST"
    echo "--sync/nosync:   Issue a sync / no sync [default: sync if remove]"
    echo "--attachpq3:     Tell kernel to attach sg to LUN 0 that reports PQ=3"
    echo "--reportlun2:    Tell kernel to try REPORT_LUN even on SCSI2 devices"
    echo "--largelun:      Tell kernel to support LUNs > 7 even on SCSI2 devs"
    echo "--sparselun:     Tell kernel to support sparse LUN numbering"
    echo " Host numbers may thus be specified either directly on cmd line (deprecated) or"
    echo " or with the --hosts=LIST parameter (recommended)."
    echo "LIST: A[-B][,C[-D]]... is a comma separated list of single values and ranges"
    echo " (No spaces allowed.)"
    exit 0
fi

if test ! -d /sys/class/scsi_host/ -a ! -d /proc/scsi/; then
  echo "Error: SCSI subsystem not active"
  exit 1
fi

# Make sure sg is there
modprobe sg >/dev/null 2>&1

if test -x /usr/bin/sg_inq; then
    sg_version=$(sg_inq -V 2>&1 | cut -d " " -f 3)
    sg_version=${sg_version##0.}
    #echo "\"$sg_version\""
    if [ -z "$sg_version" -o "$sg_version" -lt 70 ] ; then
        sg_len_arg="-36"
    else
        sg_len_arg="--len=36"
    fi
fi

# defaults
unsetcolor
lunsearch=
opt_idsearch=`seq 0 7`
opt_channelsearch=
remove=
forceremove=
optscan=1
sync=1
declare -i scan_flags=0
if test -d /sys/class/scsi_host; then
  findhosts_26
else
  findhosts
fi

# Scan options
opt="$1"
while test ! -z "$opt" -a -z "${opt##-*}"; do
  opt=${opt#-}
  case "$opt" in
    l) lunsearch=`seq 0 7` ;;
    L) lunsearch=`seq 0 $2`; shift ;;
    w) opt_idsearch=`seq 0 15` ;;
    c) opt_channelsearch="0 1" ;;
    r) remove=1 ;;
    i) lipreset=1 ;;
    -remove)      remove=1 ;;
    -forcerescan) remove=1; forcerescan=1 ;;
    -forceremove) remove=1; forceremove=1 ;;
    -hosts=*)     arg=${opt#-hosts=};   hosts=`expandlist $arg` ;;
    -channels=*)  arg=${opt#-channels=};opt_channelsearch=`expandlist $arg` ;;
    -ids=*)   arg=${opt#-ids=};         opt_idsearch=`expandlist $arg` ;;
    -luns=*)  arg=${opt#-luns=};        lunsearch=`expandlist $arg` ;;
    -color) setcolor ;;
    -nooptscan) optscan=0 ;;
    -issue-lip) lipreset=1 ;;
    -sync) sync=2 ;;
    -nosync) sync=0 ;;
    -attachpq3) scan_flags=$(($scan_flags|0x1000000)) ;;
    -reportlun2) scan_flags=$(($scan_flags|0x20000)) ;;
    -largelun) scan_flags=$(($scan_flags|0x200)) ;;
    -sparselun) scan_flags=$((scan_flags|0x40)) ;;
    *) echo "Unknown option -$opt !" ;;
  esac
  shift
  opt="$1"
done

# Hosts given ?
if test "@$1" != "@"; then
  hosts=$*
fi

if [ -d /sys/class/scsi_host -a ! -w /sys/class/scsi_host ]; then
  echo "You need to run scsi-rescan-bus.sh as root"
  exit 2
fi
if test "$sync" = 1 -a "$remove" = 1; then sync=2; fi
if test "$sync" = 2; then echo "Syncing file systems"; sync; fi
if test -w /sys/module/scsi_mod/parameters/default_dev_flags -a $scan_flags != 0; then
  OLD_SCANFLAGS=`cat /sys/module/scsi_mod/parameters/default_dev_flags`
  NEW_SCANFLAGS=$(($OLD_SCANFLAGS|$scan_flags))
  if test "$OLD_SCANFLAGS" != "$NEW_SCANFLAGS"; then
    echo -n "Temporarily setting kernel scanning flags from "
    printf "0x%08x to 0x%08x\n" $OLD_SCANFLAGS $NEW_SCANFLAGS
    echo $NEW_SCANFLAGS > /sys/module/scsi_mod/parameters/default_dev_flags
  else
    unset OLD_SCANFLAGS
  fi
fi
echo "Scanning SCSI subsystem for new devices"
test -z "$remove" || echo " and remove devices that have disappeared"
declare -i found=0
declare -i rmvd=0
for host in $hosts; do
  echo -n "Scanning host $host "
  if test -e /sys/class/fc_host/host$host ; then
    # It's pointless to do a target scan on FC
    if test -n "$lipreset" ; then
      echo 1 > /sys/class/fc_host/host$host/issue_lip 2> /dev/null;
    fi
    # Always trigger a rescan for FC to update channels and targets
    echo "- - -" > /sys/class/scsi_host/host$host/scan 2> /dev/null;
    channelsearch=
    idsearch=
    udevadm_settle
  else
    channelsearch=$opt_channelsearch
    idsearch=$opt_idsearch
  fi
  [ -n "$channelsearch" ] && echo -n "channels $channelsearch "
  echo -n "for "
  if [ -n "$idsearch" ] ; then
    echo -n " SCSI target IDs " $idsearch
  else
    echo -n " all SCSI target IDs"
  fi
  if [ -n "$lunsearch" ] ; then
    echo ", LUNs " $lunsearch
  else
    echo ", all LUNs"
  fi
  dosearch
done
if test -n "$OLD_SCANFLAGS"; then
  echo $OLD_SCANFLAGS > /sys/module/scsi_mod/parameters/default_dev_flags
fi
echo "$found new device(s) found.               "
echo "$rmvd device(s) removed.                 "