Linux 和 Windows 共享交換區

本文出自:http://www.linuxforum.net 作者: 馬軍 (Arthur Ma)

    1. 前言
    現在,越來越多的人在一台使用Linux 和 Windows. 這應該說是Linux的勝利. 我們知
    道, Linux 要使用交換分區，
    Windows 要使用交換文件。如果一台PIII, 有192M 內存，我們分配給Linux 192M 交換
    區， Windows 2000 至少要
    200M. 那，我們要用近400M硬盤空間。如果交換區更大，浪費就更可觀了。
    由兩個系統的交換區都只是運行時的臨時數據,所以,我們採用動態修改分區信息的方法
    來達到共享目的.

    2. 方法簡介
    1). 備份Windows 分區信息。
    2). 當啟動Linux時， 將該分區做成Linux 交換區，並將其激活。
    3） 當Linux 關閉時，將該分區重新變成Windows 交換區。

    3. 具體步驟
    1). 分區
    Fdisk, 只分主分區, 不分擴展分區
    2). 安裝 Windows.
    3). 安裝Linux (佔一個主分區)
    4). 在Linux 下, 分擴展分區)
    5). 設定Linux交換區(假定/dev/hda10)
    6). 建立winswap 設備
    ln -s /dev/hda10 /dev/winswap
    7). 啟動Linux, 關閉交換區
    # swapoff -a
    8). 從文件安裝表中刪除該分區
    vi /etc/fstab
    注釋掉該行 (/dev/hda10)
    9). 將該分區該成 FAT16 或其他 DOS 分區.
    10). 啟動 Windows
    a). 格式化該分區
    b). 將系統的交換文件設在該分區.
    11). 啟動 Linux, 計算Total Special Sectors
    公式:
    T = r + (s * f) + (d / 16)
    參數:
    Reserved Sectors at beginning : r
    FAT Copies : f
    Sectors per FAT : s
    Root directory entries : d
    參見: msinfo.sh
    注解: 可以運行 msinfo.sh 來獲得.
    # msinfo.sh /dev/hda10

    12). 備份Windows 分區信息
    # dd if=/dev/winswap bs=512 count=XXX | gzip -9 > /etc/winswap.gz
    這裡, XXX = T
    14). 編寫啟動, 退出腳本, 並把它們放在 /etc/rc.d/xxx.
    可用 grep -nr * | grep swapon (或 swapoff) 來找系統激活和關閉交換區, 將它們
    替換稱我們
    的腳本)
    我們在附錄中提供了啟動和關閉的腳本.
    4. 附加說明
    1. 本文使用的是FAT16, 如果使用NTFS 或其它, 必須修改腳本.
    2. mkswap /dev/winswap 377496 (這個值需要修改, 依照你的分區大小)

    5. 參考資料:
    Linux HOWTO: Swap-space

    6. 附錄 -- 相應的腳本
    1. msinfo.sh 腳本
    #!/bin/sh
    #
    # msinfo.sh This shell script displays the boot sector of the
    # given partition.
    #
    # Author: Rahul U. Joshi
    #
    # Modifications Removed the use of expr and replaced it by the let
    # command.


    # check for command line arguments
    if [ $# -ne 1 ]; then
    echo "Usage: msinfo "
    exit 1
    fi

    # check whether the input name is a block device
    if [ ! -b $1 ]; then
    echo "msinfo: $1 is not a block device"
    exit 1
    fi

    # create two temporary files for use
    TMPFILE=`mktemp -q /tmp/$0.XXXXXX`
    if [ $? -ne 0 ]; then
    echo "msinfo: Can't create temp file, exiting..."
    exit 1
    fi

    TXTFILE=`mktemp -q /tmp/$0.XXXXXX`
    if [ $? -ne 0 ]; then
    echo "msinfo: Can't create temp file, exiting..."
    rm -f $TMPFILE
    exit 1
    fi

    back_title="`printf "%78s" "msinfo, Information about FAT16 filesystem --
    Rahul
    Joshi"`"

    dialog --title "Boot sector of $1" --backtitle "$back_title" --infobox
    "\nAnalysing boot sector for $1\nPlease wait ..." 14 60

    # truncate TXTFILE to zero length
    echo > $TXTFILE

    # get Formatting DOS version
    dd 2>/dev/null if=$1 bs=1 count=8 skip=3 | dd 2>/dev/null of=$TMPFILE
    printf >>$TXTFILE "%30s : %s\n" "Formatting DOS version" "`cat $TMPFILE`"


    # get file system
    dd 2>/dev/null if=$1 bs=1 count=8 skip=54 | dd 2>/dev/null of=$TMPFILE
    printf >>$TXTFILE "%30s : %s\n" "Filesystem" "`cat $TMPFILE`"

    # check if filesystem in a FAT16
    if [ "`cat $TMPFILE`" != "FAT16 " ]; then
    dialog --title "Boot sector of $1" --backtitle "$back_title" --infobox
    "\nCan't find a FAT16 filesystem on $1" 14 60
    exit 2
    fi

    # get volume label in boot sector
    dd 2>/dev/null if=$1 bs=1 count=11 skip=43 | dd 2>/dev/null of=$TMPFILE
    printf >>$TXTFILE "%30s : %s\n" "Volume label in boot sector" "`cat
    $TMPFILE`"

    # get Sector size
    dd 2>/dev/null if=$1 bs=1 count=2 skip=11| od -An -tdS | dd 2>/dev/null
    of=$TMPFILE
    printf >>$TXTFILE "%30s : %d\n" "Sector size" `cat $TMPFILE`
    sector_size=`cat $TMPFILE`


    # get Reserved sectors
    dd 2>/dev/null if=$1 bs=1 count=2 skip=14| od -An -tdS | dd 2>/dev/null
    of=$TMPFILE
    printf >>$TXTFILE "%30s : %d\n" " Reserved sectors" `cat $TMPFILE`
    reserved_sectors=`cat $TMPFILE`


    # get FAT sectors
    dd 2>/dev/null if=$1 bs=1 count=1 skip=16| od -An -tdS | dd 2>/dev/null
    of=$TMPFILE
    fat_count=`cat $TMPFILE`

    dd 2>/dev/null if=$1 bs=1 count=2 skip=22| od -An -tdS | dd 2>/dev/null
    of=$TMPFILE
    sectors_per_fat=`cat $TMPFILE`

    # calculate the no of sectors allocated for FAT's
    let fat_sectors=fat_count*sectors_per_fat

    printf >>$TXTFILE "%30s : %u (%u x %u) \n" "FAT sectors" "$fat_sectors"
    "$fat_count" "$sectors_per_fat"


    # get root directory sectors
    dd 2>/dev/null if=$1 bs=1 count=2 skip=17| od -An -tdS | dd 2>/dev/null
    of=$TMPFILE
    root_sectors=`cat $TMPFILE`

    # calculate the no of sectors allocated for root directory
    let root_sectors=root_sectors*32/sector_size

    printf >>$TXTFILE "%30s : %u\n" "Root directory sectors" "$root_sectors"


    # get Total special sectors
    let total=reserved_sectors+fat_sectors+root_sectors
    printf >>$TXTFILE "%30s : %u\n" "Total special sectors" "$total"

    # display the information in a message box
    dialog --title "Boot sector of $1" --backtitle "$back_title" --msgbox
    "`cat $TXTFILE`" 14 60

    # delete temporary files
    rm -f $TMPFILE
    rm -f $TXTFILE

    # end of msinfo.sh

    2. swapinit.sh
    #!/bin/sh
    #
    # /etc/rc.d/init.d/swapinit.sh - activate the swap partition
    #
    # written by Rahul U. Joshi
    # Verify and initialize swap space
    #

    echo -n 'Verifying swap space... '

    loopcount=0

    # flag to indicate whether the partition has been activated or not
    activated=0

    # check for signatures 6 times before giving up
    while [ $loopcount -lt 6 ]
    do
    if [ "`/bin/dd 2>/dev/null if=/dev/winswap bs=1 count=10 skip=4086`" =
    'SWAPSPACE2' ]; then

    echo "Linux signature found, iteration $loopcount"
    echo "Activating swap partitions"
    swapon /dev/winswap
    activated=1
    break

    elif [ "`/bin/dd 2>/dev/null if=/dev/winswap bs=1 count=5 skip=54`" =
    'FAT16' ]; then
    echo "DOS signature found, iteration $loopcount"
    echo "Making swap partition"
    mkswap /dev/winswap 377496
    echo "Activating swap partitions"
    swapon /dev/winswap
    activated=1
    break

    else
    let loopcount=loopcount+1
    fi

    done


    if [ $activated -ne 1 ] ; then
    echo "Swap signature not found after $loopcount tries"
    echo "No swapping partitions activated"
    exit 1
    fi

    3. swaphalt.sh
    #!/bin/sh
    #
    # /etc/rc.d/init.d/swapinit.sh - activate the swap partition
    #
    # written by Rahul U. Joshi
    # Verify and initialize swap space
    #

    echo -n 'Verifying swap space... '

    loopcount=0

    # flag to indicate whether the partition has been activated or not
    activated=0

    # check for signatures 6 times before giving up
    while [ $loopcount -lt 6 ]
    do
    if [ "`/bin/dd 2>/dev/null if=/dev/winswap bs=1 count=10 skip=4086`" =
    'SWAPSPACE2' ]; then

    echo "Linux signature found, iteration $loopcount"
    echo "Activating swap partitions"
    swapon /dev/winswap
    activated=1
    break

    elif [ "`/bin/dd 2>/dev/null if=/dev/winswap bs=1 count=5 skip=54`" =
    'FAT16' ]; then
    echo "DOS signature found, iteration $loopcount"
    echo "Making swap partition"
    mkswap /dev/winswap 377496
    echo "Activating swap partitions"
    swapon /dev/winswap
    activated=1
    break

    else
    let loopcount=loopcount+1
    fi

    done


    if [ $activated -ne 1 ] ; then
    echo "Swap signature not found after $loopcount tries"
    echo "No swapping partitions activated"
    exit 1
    fi