topic Re: how to use 5th partition? in Operating System - Linux

how to use 5th partition?

Hanry Zhou — Tue, 09 Sep 2003 17:54:27 GMT

I have already used up 4 patitions, 1 of them for window NT, two for linux, and last one for bootitNG (a parition tool).
Now I have one more partition unused, and wanted to add it into one of linux partition, how do I do that?
If I hvae to use any extra tools to achieve that, where I can get that tool? please also specify it.

Thanks,

Re: how to use 5th partition?

Mark Grant — Tue, 09 Sep 2003 18:13:14 GMT

This one bothers me somewhat as you can only have four primary partitions on an ide disk. If you really have five partitions, perhaps one is extended then one thing you can do with it is add to a volume group under linux or just create a linux file system.

If you create a volume group and vgextend it to include your fifth partition, you can create fileystems that extend across the two partitions and you can increase and decrease the size of them as your needs change.

However, if you just create a file system on your fifth partition it will be just one filesystem that you can use for storage but it isn't as flexible.

Check out linux LVM

Re: how to use 5th partition?

Hanry Zhou — Tue, 09 Sep 2003 18:41:38 GMT

You have to create the partition first before you can use LVM to add the partition into a volume group. It won't let me create a new partition, since the number of primary paritions have already reached, as you inidicated.

Anybody idea else?

Re: how to use 5th partition?

Mark Grant — Tue, 09 Sep 2003 18:48:31 GMT

Ahhh,

The only way you can get more than 4 partitions is to make one of your existing partitions contain several extended partitions which will destroy any existing data in it.

However, you say that bootitNG uses an entire partition. This seems a bit extreme to me. Are you sure?

From Linux, if you run fdisk /dev/hda (assuming that is the device for your disk and then enter "p", it will show you if you have any unpartitioned sace you can use.

WARNING do not change any partion information you have unless you are confident that it is right or you will destroy things. particularly don't change partitions you have an OS installed in.

Re: how to use 5th partition?

Hanry Zhou — Tue, 09 Sep 2003 20:18:59 GMT

Mark,

Thanks for your response.

Bootit did use the entire partition as seen in fdisk.

Now, the questions is, can I use /dev/hda4 being used for linux swap as a extended partition, then from which to create logical partition? Since I don't want to destroy any data on other 3 paritions: linux, win NT, and bootit.

Thanks again,

Re: how to use 5th partition?

Jerome Henry — Wed, 10 Sep 2003 12:19:59 GMT

Hi,

As Mark says, you can only have four primaruy partitions on an IDE disk. If your partitions are hda1, hda2, hda3 and hda4, all primary, then you can't change witgout distroying data on your last partition. Check it with fdisk /dev/hda, then p to see the details.

hth

J

Re: how to use 5th partition?

Hanry Zhou — Wed, 10 Sep 2003 13:28:19 GMT

J,

I know everything you said here, but since I have already used all these 4 partitions, and how I can create extended partition, then from there to create logical paritions. I know I have to destroy one of existing 4 partitions in order to setup the extended one, so can I destroy the "linux swap" first, then create the extended one on it?

Re: how to use 5th partition?

Patrick Van Humbeeck — Wed, 10 Sep 2003 13:48:12 GMT

Hello,

You can remove your swap partition and then recreate it inside your new extended partition.
Be sure to turn it off first with swapoff /dev/hda4 (assuming it's hda4).
Providing your system has enough ram this should not be an issue but I would do this in single user mode, (or maybe even better, by booting from an install CD (in witch case you dont need to deactivate it)).

If you do it from the running system you can temporarily add a swap file on the linux partition like this :

# dd if=/dev/zero of=/swap bs=1024 count=16384
# mkswap /swap 16384
# sync
# swapon /swap

once you got rid of it (swapoff) you can just scratch the partition and recreate from fdisk, be sure to recreate an extended partition for swapping inside the new extended one, along with any more partitions you want to create.

you can then reactivate it with

# mkswap /dev/hda5 (assuming hda5, extended partitions start with 5)
# sync
# swapon /dev/hda5

and then deactivate the temporary swap file you might have created.

be sure to modify /etc/fstab ! you need to change whatever your previous swap partition was into the new one.

hope this helps :)

Re: how to use 5th partition?

Hanry Zhou — Wed, 10 Sep 2003 14:41:16 GMT

Patrick,

Your posting definitely helps me a lot.

Now only one question (I hope) left is what steps involved to setup extended partition, and create logical partition inside of extended? I assume I can use fdisk to achieve that, but can you list these steps for me?

Thanks,

Re: how to use 5th partition?

Eric Ladner — Wed, 10 Sep 2003 15:10:46 GMT

Once you get into fdisk, it's pretty obvious. The dos fdisk.com makes a distinction between creating a primary and creating an extended partition (they are different menu items).

The linux fdisk asks you when go through creating a partitoin what type you want it to be (primary/extended).

You can probably also use tools like partition magic to convert your last primary partition into an extended partition so you don't have to mess with the data that much, otherwise you have to destroy the fourth partition to create the extended partition.

Re: how to use 5th partition?

Patrick Van Humbeeck — Wed, 10 Sep 2003 15:25:41 GMT

Hanry,

As Eric put it, it's pretty straightforward from fdisk to do so. use 'd' to delete the previous swap partition, then 'n' to create one and choose extended. for this extended partition you should use all the space left on the drive.

once you have one extended partition you can can keep adding as many partitions as you want, numbered from 5 to (whatever ammount of partitions you want). you will not be able to use /dev/hda4 anymore after this (assuming hda4 was the previous swap partition) as it'll become a container for the extended partitions. instead you'll be able to access /dev/hda5, 6 , etc.

the output from 'p' will look a bit like this :

Device Boot Begin Start End Blocks Id System
/dev/hda1 1 1 60 120928+ 6 DOS 16-bit >=32M
/dev/hda2 61 61 126 133056 63 GNU HURD
/dev/hda3 127 127 192 133056 a5 BSD/386
/dev/hda4 193 193 525 671328 5 Extended
/dev/hda5 193 193 255 126976+ 81 Linux/MINIX
/dev/hda6 256 256 525 66496+ 82 Linux swap

(don't pay attention to the partition types, I fetched this from google as I cannot ssh to my linux system from here).

notice that partition /dev/hda4 is marked as 'extended' and goes from sector 193 to the end of the drive (525) and hda5 & hda6 are actually inside hda4 (looking at start and end sectors).

Re: how to use 5th partition?

Jerome Henry — Wed, 10 Sep 2003 19:29:49 GMT

To add to PAtrick tips, I would boot on linux install cd, say it's a redhat, and choose 'linux rescue' mode. The system will be booted in RAM, your HD partitions read, and a root shell given.
From then , I would use 'chroot /mnt/sysimage' to avoid having my whole system under a /mnt/sysimage subdir, then ./fdisk /dev/hda, and here we go.

hth

J

Re: how to use 5th partition?

Hanry Zhou — Wed, 10 Sep 2003 20:50:23 GMT

thank you all for these wonderful postings.

Now I have one more question left before I assign my points.

Currently /boot is on under one big file system /, since I have additional partition I can use, I wanted to move/copy /boot to a seperated partition, how should I accomplish that. I know /boot is special boot area, any special thing I have to do, in order to create /boot file system, and move everything under /boot over?

Thanks again,

Re: how to use 5th partition?

Patrick Van Humbeeck — Thu, 11 Sep 2003 07:37:24 GMT

well, you do not _have_ to move /boot to its own partition, it's nice to do so in case you want to keep it unmounted during normal system use but to be honest, I never really saw any advantage in doing so, if you hose the system then it's not an intact /boot that's going to help :)

but if you want to do it anyway, all you need to do is to create a new partition, copy the files from the old one into it and then modify /etc/fstab and /etc/lilo.conf (or /boot/grub/grub.conf, depending on which bootloader you use). make sure you rerun 'lilo' after modifying lilo.conf, and keep the install cd at hand in case something goes wrong and you need to boot in rescue mode to recover.
I'd suggest first changing swap partitions, reboot, and then only try moving /boot.