1. 簡介
本文介紹通過VMware建立Centos無盤系統的測試過程
基本實現原理：在Image Server上建立dhcp,tftp,nfs服務，然後啓動diskless client—>dhcp獲得IP—>tftp獲取內核文件vmlinuz(可引導的、壓縮的內核), initrd.img(用來臨時的引導硬件到實際內核vmlinuz能夠接管並繼續引導的狀態)--->通過nfsroot(Mounting the root filesystem via NFS)來掛載根分區到Image Server上實現無盤系統
2. 通過Yum 安裝dhcp,tftp,nfs ,busybox-anaconda(用於redhat的安裝管理程序一個單一的binary,包含大量系統指令,包括shell), system-config-netboot-cmd(用於命令行下建立無盤環境)
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l yum –y install dhcp tftp nfs-utils nfs-utils-lib busybox-anaconda system-config-netboot-cmd |
3. 修改dhcp配置文件並啓動
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l vi /etc/dhcpd.conf
allow bootp; allow booting;
ddns-update-style interim; ignore client-updates;
subnet 192.168.159.0 netmask 255.255.255.0 { range 192.168.159.200 192.168.159.220; default-lease-time 21600; max-lease-time 43200; option routers 192.168.159.2; option domain-name-servers 192.168.159.2; option subnet-mask 255.255.255.0; option domain-name "pwrd.com"; option time-offset -18000; filename "linux-install/pxelinux.0"; #需要指定pxelinux.0(PXE啓動引導文件)的位置，默認在/tftpboot下 next-server 192.168.159.120; #指定tftp的IP地址
#可以指定diskless client的IP地址 host test4 { hardware ethernet 00:0c:29:a3:86:c3; fixed-address 192.168.159.130; } }
#啓動dhcp, 如有報錯可以查看/var/log/messages 中的log l /etc/init.d/dhcpd start |
4. 修改tftp配置文件並啓動
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l vi /etc/xinetd.d/tftp
service tftp { socket_type = dgram protocol = udp wait = yes user = root server = /usr/sbin/in.tftpd server_args = -s /tftpboot #指定tftp下載的主目錄 disable = no #從yes改爲no per_source = 11 cps = 100 2 flags = IPv4 }
#啓動tftp, 如有報錯可以查看/var/log/messages 中的log l /etc/init.d/xinetd start |
5. 建立diskless client所需要的root目錄,並同步系統文件到diskless root目錄中,在根目錄下排除不需要的目錄即可,比如/proc /sys
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l mkdir -p /diskless/centos/test4/root/
#192.168.159.120爲本機,p_w_picpath server l rsync -v -a -e ssh --exclude='/proc/*' --exclude='/sys/*' --exclude='/mnt/*' 192.168.159.120:/ /diskless/centos/test4/root/
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6. 修改NFS配置文件,指定掛載目錄,並啓動NFS服務
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#snapshot 是爲了那些每一個diskless client都需要讀寫的部分，例如/var/log/messages等 l vi /etc/exports /diskless/centos/test4/root/ *(rw,sync,no_root_squash,no_all_squash) /diskless/centos/test4/root/snapshot/ *(rw,sync,no_root_squash,no_all_squash)
#啓動portmap 和NFS, 如有報錯可以查看/var/log/messages 中的log /etc/init.d/portmap start /etc/init.d/nfs start
查看rpcinfo和export list rpcinfo –p showmount -e 192.168.159.120
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7. 命令下設置diskless的引導環境
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#The “pxeos” enables you to create a new operating system under /tftpboot and places the vmlinux and initrd p_w_picpaths there. Options for “pxeos”: #生成NFS引導的內核文件 l pxeos -a -i centoskernel -p NFS -D 1 -s 192.168.159.120 -L /diskless/centos/test4 centoskernel
#查看pxeos是否成功 l pxeos -l
#查看NFS引導的內核文件是否生成 l ll /tftpboot/linux-install/centoskernel/
#查看pxeos生成的配置文件 l more /tftpboot/linux-install/pxelinux.cfg/pxeos.xml
The “pxeboot” command adds clients to the diskless environment and creates the HEX file for the host in the /tftpboot directory Options for “pxeboot”: #生成diskless client所需要的啓動文件，指定IP爲192.168.159.130 l pxeboot -a -O centoskernel -r 28753 -S test4 -e eth0 -s console=ttyS0,115200n8r 192.168.159.130
#也可以不用pxeboot命令，而用01+MAC地址作爲文件名（注意小寫,由於PXE的尋址規律） l cat /tftpboot/linux-install/pxelinux.cfg/01-00-0c-29-a3-86-c3 default centoskernel label centoskernel kernel centoskernel/vmlinuz append console=ttyS0,9600n8 initrd=centoskernel/initrd.img root=/dev/ram0 init=diskle***c NFSROOT=192.168.159.120:/servers_drbd/centos/coreclient/test4 ramdisk_size=28753 ETHERNET=eth0 SNAPSHOT=test4
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8. 新建一臺Vmware,只需分配內存和CPU,作爲diskless client
如何獲取MAC地址:
diskless client啓動時會廣播DHCP request, 在Image Server中 tail -f /var/log/messages可以看到,根據step 7中的格式寫入到/tftpboot/linux-install/pxelinux.cfg中,或者寫入到step 3中的dhcpd.conf,並分配固定IP地址,然後用step 7中的pxeboot生成啓動文件
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l tail -f /var/log/messages Dec 11 00:50:29 test3 dhcpd: DHCPDISCOVER from 00:0c:29:a3:86:c3 via eth0 Dec 11 00:50:29 test3 dhcpd: DHCPOFFER on 192.168.159.130 to 00:0c:29:a3:86:c3 via eth0 Dec 11 00:50:31 test3 dhcpd: DHCPREQUEST for 192.168.159.130 (192.168.159.120) from 00:0c:29:a3:86:c3 via eth0 Dec 11 00:50:31 test3 dhcpd: DHCPACK on 192.168.159.130 to 00:0c:29:a3:86:c3 via eth0
l ls /tftpboot/linux-install/pxelinux.cfg/01-00-0c-29-a3-86-c3
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9. 啓動成功後可以檢查diskless client和p_w_picpath server的同步情況
由於NFS設置成了sync模式,則在diskless client上的任何增刪改操作都會實時同步到p_w_picpath server的nfs 掛載目錄
參考資料：