Hello, i have a server which i have no physical access to, all i can do is boot in rescue mode from a live debian CD

and i want to know of a way to install CentOS from iso image or maybe NFS? on that server using this debian live CD.

since it's live CD i can't mount the iso image and boot from it cos after reboot nothing will be preserved.

so the case in breif is, i am booted form debian live cd and i want to install CentOS on the machine from that system using iso image

thanks

If your Debian Live CD can see all disks and has a network connection you could:
- partition the first harddisk to at least have one ext2/ext3 primary partition ("/boot"?) that will hold the unpacked kernel and initrd (9 megs total),
- install GRUB in this partition,
- download CentOS-5.5-i386-netinstall.iso, loop-mount it and copy isolinux/initrd.img and isolinux/vmlinuz to the partition,
- edit /boot/grub/grub.conf so it looks something like where "ks=" means you're using a previously kickstart file like
and "nfs:" means you'll be using a NFS share (you previously set up) at address "192.168.0.1" and where the Kickstart file can be found at ":/kicks/ks.cfg" and the packages from the full ISO at "/exports/CentOS_5.5_i386".
I'm not giving any guarantee this will work and this is only an outline. I suggest you set up VMware, QEmu or VirtualBox to test out this hypothesis. YMMV (VM)

* Another way, if you know the first harddisks HW details and have an exact remote replica to use, could be to perform a minimal CLI-only installation of Centos on that replica and use 'netcat' to 'dd' the remote image directly to the server.

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Thanks a lot for your help, I'm gonna try this on virtual box first as you recommended and see what it will result into.

but i have a question, in this case we mounted the drive on / directory.

and during installation we are reformatting the hard drive! is this ok? things are all loaded to ram removing them won't be a problem?

i have 2 hard drives on that machine so what would i modify in the grub.conf and the ks file to load the files from the other hard drive instead of the network?

now there is the other case i wish you to help me figure:

if say i want to do it in alternative way, i have the CentOS iso image, and i downloaded it on the second hard drive then mounted it.

i have KVM connected so i don't have problem following up the machine while it's booting.

how should i edit grub to make it boot from that iso image?

and after it boots from the iso image! will i be able to unmount the first hard drive so i can be able to partition it again?

i forgot to mention that i already have CentOs installed and all i want is clean re-installation.

so in brief:

i have debian live CD in the CD-ROM
i have KVM over IP
i have 2 hard drives sda and sdb
i have Centos isntalled on one sda
and i have Centos installation iso on sdb

i assume the procedure will be:

booting into my system normally and mounting the iso image:
i can't figure how to edit grub though

then after that i will find the option in the grub loader? to boot from the iso file? after that i will be able to continue with the installation since I'm now booted from the iso image to format the first hard drive and reinstall the the centos.

when the installation is complete i should reboot to see the new grub loader and chose boot from the new system

is what i mention above possible? cos i did some search and found couple of ppl saying it's not possible to boot from iso image.

waiting for your replies

thanks

Which drive? When booting the kernel will load in RAM so it doesn't matter where you mounted the ISO previously.


Since you have KVM access I'd say just get GRUB to boot the extracted netinstall ISO kernel, forget the Kickstart ks file and just do a network installation. Using a regular Centos CDROM or DVD it should offer file:// and http:// install but I'm not sure the netinstall will. Check the Centos Wiki or Red Hat documentation to make certain (or just boot the ISO in your VMware, QEmu or VirtualBox).


As far as I know the version of GRUB Centos uses doesn't do ISO boots, you'd need GRUB 2 for that. Installing that shouldn't be a problem either as the installation will overwrite GRUB anyway.


Extracted kernel boots Linux in RAM, shoud not be a problem.


Any particular reason why? Since you already have a Centos installation you only need to extract the kernel as instructed before, add it to GRUB, boot it and proceed with the installation.

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Thanks a lot for your help, everything is working fine on the virtual box so i should be fine to proceed and do it on the server.

well as for re-installation, this server is a testing server and i messed it up very bad and now lots of files are missing and there are lots of applications installed on it.

i decided to lunch web hosting service on that server, and will install cPanel and you know cPanel needs fresh server otherwise things might not work as expected. so i will re-install CentOS for that.

after all i guess i might just ask the provider to insert a CentOS installation DVD in the DVD-ROM tray, this will make it much faster and easier.

ROTFL. Indeed that should be the most efficient option.