Partitioning for 2 linux OS's

JohnUSNret · 10-30-2010, 09:25 AM

Q: How to set a Dual boot for 2 linux OS's on a 80GB HD? I have 5 Lenny 5.0.5 DVD's and that is currently installed. No data on current setup needs to be saved. So a reinstall is not a problem. Would like to set up as follows: 1st OS permanent Lenny 5.05 (about 50GB). 2nd OS space (about 30mg) is (testing) or playing with CD/DVD's of the month. My background: I did S/W development on the HPUX about 100 yrs. ago, so I can just get around the command line. TIA John at The Villages FL

CORRECTED mg to GB sorry.

udaman · 10-30-2010, 09:44 AM

Each Linux distro takes about 6 to 7 GB of drive space for the / partition. I currently have three hard drives on my system, one 40GB for OpenSuse, one 80 GB for Slackware and future installs, and one 1 TB as a data drive. I plan on installing FreeBSD and Debian on the 80GB drive, /dev/sdc, and using a common /home directory on /dev/sdc2, which may not be a good idea, so I'll create two more 7GB partitions on /dev/sdc. To see my partition setup, here's the o/p of sfdisk, where /dev/sda and /dev/sdc are the OS drives.

Code:

# sfdisk -l

Disk /dev/sda: 4865 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sda1          0+    261     262-   2104483+  82  Linux swap / Solaris
/dev/sda2   *    262    2125    1864   14972580   83  Linux
/dev/sda3       2126    4864    2739   22001017+  83  Linux
/dev/sda4          0       -       0          0    0  Empty

Disk /dev/sdb: 121601 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdb1          0+ 121600  121601- 976760001   83  Linux


Disk /dev/sdc: 9729 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdc1   *      0+   1305    1306-  10490413+  83  Linux
/dev/sdc2       1306    3979-   2674-  21473715   83  Linux
/dev/sdc3       6529    6790     262    2104515   82  Linux swap / Solaris
/dev/sdc4          0       -       0          0    0  Empty

stress_junkie · 10-30-2010, 09:47 AM

There's a lot that one could say on the subject. Lots of good contradictory advise could be argued equally well for both sides issues. That said this is what I would do with an 80 GB disk drive.

I would create four primary partitions. The first two would be for Linux. The third would be for a common /home. The fourth would be for swap space.

Partition 1: 20 GB type ext3
Partition 2: 20 GB type ext3
Partition 3: 36 GB type ext3
Partition 4: 4 GB type swap

You could do this with a bootable Linux CD distribution. Open a terminal window. Use cfdisk to create the partitions.

Caveats:
1 - The last distribution that you install will always make itself the default operating system in the boot menu.
2 - Ubuntu and its derivatives are now using GRUB 2 which is quite different than the beloved GRUB (legacy) that is used by other distributions. (Don't get me started.)
3 - Some distributions like Fedora will not even look for other operating systems to include in a boot menu.

I would reinstall Lenny then use a terminal emulator to make a copy of the disk MBR. Put that copy in the /root directory of Lenny. That way you can go back to having Lenny's boot menu even if the second Linux distribution has installed GRUB 2.

Code:

dd if=/dev/sda of=/root/original-mbr.dd bs=512 count=1 conv=notrunc,noerror

Other than those ideas I would say go ahead with reinstalling your Lenny with the disk partitioned as above then ask specific questions as they arise.

Good luck and most of all have fun.

Hungry ghost · 10-30-2010, 11:05 AM

A couple of things I would suggest:

1) If you're going to use a shared home partition (which I would suggest, given the limited HD space), you may have problems with the apps settings of the two distros you install, in case you use the same user for both. I think there are ways to fix this, but maybe the simpler way is to just use different users in both installs (for example, "user1" for debian, and "user2" for the second distro you install); this way you don't have to worry for the problems that may arise when different program versions mess your user settings.

2) I don't know how this works on other distros, but in case you have problems with some distro's grub not recognizing the other distro, the solution on debian is quite simple (assuming that you can boot it): first install os-prober, and then execute update-grub as root; it will automatically search your HD for other OSs, and add them to the boot menu.

A third suggestion is, why not use debian testing instead of debian lenny? It's your choice of course, but if you're going to use this pc as a regular desktop (not a server), debian testing will be better IMO, since it has more up-to-date packages than the stable branch (and it's actually very stable).

Greetings.

JohnUSNret · 11-11-2010, 08:53 AM

Resolving Problem with non-local LUG, Orlando FL, John

Absent Minded · 11-13-2010, 01:02 AM

Hi John,
I am with the last poster on your questions.. I think a fresh install of Squeeze and formatting the partitions as ext4 (instead of ext3 the Debian default) will go a long way to making you a happy Debian stable user in a couple months. I suggest the clean/fresh install instead of the upgrade as ext4 offers many additional benefits when done on the install instead of upgrading it later. I use it already on my system and the performance boost is quite noticeable even on my old PATA 80GB HD. Also by using Squeeze instead of Lenny, you have a better chance of having access to your future testing installs over the next couple years. Just remember, you have to manually select ext4 during the partitioning as Debian defaults to ext3. Many other distros use ext4 by default already to take advantage of it's benefits over ext3.

Peufelon · 11-14-2010, 02:18 AM

I have run into trouble trying to cram the "all but home" partitions into fewer than 10 GB. Keep in mind that as security upgrades and so on accumulate, you may start to find yourself running out of room. I originally budgeted about what udaman did, and have concluded I should have been more generous. Sounds like you have plenty of room to leave more space for "all but home".