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Do you use a /boot/ ???
yes
80%
 80%  [ 155 ]
no
16%
 16%  [ 31 ]
dont you need linux for that?
1%
 1%  [ 3 ]
is that my swap file?
1%
 1%  [ 3 ]
Total Votes : 192

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chemical
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PostPosted: Sat Apr 27, 2002 11:10 pm    Post subject: Significance of multiple partitions Reply with quote

Can anybody explain what the significance of having more than just / for a partion. For example, why do people like to make partitions for /home, /etc, /var. I can understand /boot (i think) but can't understand anything else. If anybody can clear this up for me it would be great.
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fuji
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PostPosted: Sat Apr 27, 2002 11:18 pm    Post subject: Re: Significance of multiple partitions Reply with quote

chemical wrote:
Can anybody explain what the significance of having more than just / for a partion. For example, why do people like to make partitions for /home, /etc, /var. I can understand /boot (i think) but can't understand anything else. If anybody can clear this up for me it would be great.


People like to keep /var out of the main filesystem. Reason being /var holds the logs, so we wouldn't want logs overflowing our filesystem.

/usr, /home, /etc are put on seperate partitions to make formatting easier afaik. That way, you can nuke your main system, while still retaining your home directory, config files and software.

Those were at least my impressions. Though i wouldn't be surprised if there were some more technical reasons.

Hope this helps
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celtic_hack
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PostPosted: Sun Apr 28, 2002 3:35 am    Post subject: Re: Significance of multiple partitions Reply with quote

chemical wrote:
Can anybody explain what the significance of having more than just / for a partion. For example, why do people like to make partitions for /home, /etc, /var. I can understand /boot (i think) but can't understand anything else. If anybody can clear this up for me it would be great.


As fuji wrote. Seperating /var from /usr keeps you're system from locking up if the logs fill up. /home is where you keep your users files, and allows upgrades without the destruction of important files.

It is also a good idea to put the swap file on a seperate disk entirely. It increases performance if on seperate controllers.

Security is also espoused as a benefit. I don't agree with that.
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chemical
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PostPosted: Sun Apr 28, 2002 4:05 am    Post subject: Re: Significance of multiple partitions Reply with quote

celtic_hack wrote:

It is also a good idea to put the swap file on a seperate disk entirely. It increases performance if on seperate controllers.


My only question would be, Is swamp really used all that much now a days with the high amounts of ram? You can expect to see up to 512 megs of ram in some servers. Would that swap space on a seperate disk make a noticable diffrence in system preformance?
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celtic_hack
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PostPosted: Sun Apr 28, 2002 4:20 am    Post subject: Re: Significance of multiple partitions Reply with quote

chemical wrote:
celtic_hack wrote:

It is also a good idea to put the swap file on a seperate disk entirely. It increases performance if on seperate controllers.


My only question would be, Is swamp really used all that much now a days with the high amounts of ram? You can expect to see up to 512 megs of ram in some servers. Would that swap space on a seperate disk make a noticable diffrence in system preformance?


It really depends on what you're doing with a server. It will make a significant difference in a CAD/CAM box, or highend graphics development machine, or very large databases. Generally though most people don't have those kinds of demands. ;')
I still use some of those antiques that make use of swap though, so it is important to me to use it [in some cases]. It is nice on my design machine, 3-D modeling is very time consuming.
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apokalyptik
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PostPosted: Thu Sep 12, 2002 6:46 am    Post subject: O.K. Call me dumb, but.... Reply with quote

Would you guys offer me a good explanation of why a /boot/ partition is needed, advantages, disadvantages, why you would not want it on the same partition as /, etc?

...Because i'm at a loss as to why it's needed. I dont use one myself, but I'm helping people ithat I know into using linux with gentoo, and I cant seem to really get a good answer from the ether on this question..

Thanks in advance for the clarification
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[UK]Superdude
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PostPosted: Thu Sep 12, 2002 6:54 am    Post subject: Reply with quote

AFAIK a seperate /boot which is not mounted as defualt (as per the install guide) is there so you dont accidently kill your kernel.
Seems fair enough to me, normal operations shouldnt cause you to need to see /boot at all

There may be other reasons, but this is what I had always presumed.
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rac
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PostPosted: Thu Sep 12, 2002 6:58 am    Post subject: Reply with quote

The official Gentoo take on this is in the install guide.
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PostPosted: Thu Sep 12, 2002 7:44 am    Post subject: Reply with quote

How can you boot a system without it? Oh, you mean a seperate partition? ;)
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Naan Yaar
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PostPosted: Thu Sep 12, 2002 3:03 pm    Post subject: Reply with quote

I have a contrary opinion in this case. I think it is perfectly fine not to have /boot as a separate partition. Reasons:

  • Assuming that boot is a directory in / rather than a separate partition and you somehow borked bzImage, it is not a big deal to rebuild it. Even if you cannot boot with the bad bzImage, it is not a big deal to mount with the install CD and rebuild the kernel
  • Even if you have a separate boot partition, kernel modules are still in the root partition. So, not a lot of safety there
  • If you screwed up your / partition that contained a boot directory, you have other things to worry about more than the kernel which can be regenerated.
  • Based on the number of issues related to an unmounted /boot when copying bzImage over, I think that the marginally improved safety it affords is not worth the hassle
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pizen
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PostPosted: Thu Sep 12, 2002 5:20 pm    Post subject: Reply with quote

Isn't the thinking that if /boot and / are separate partitions and / becomes fubar then the system will still boot and you can start the recovery process with the backups you should be making all the time?
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Naan Yaar
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PostPosted: Thu Sep 12, 2002 5:32 pm    Post subject: Reply with quote

If you are going to back-ups, it is probably better to assume that the whole drive is toast. Anyway, if modules are in "/", having /boot intact may not leave you in a bootable state. Besides, booting from the install disk or recovery disk should be OK to restore the system.
pizen wrote:
Isn't the thinking that if /boot and / are separate partitions and / becomes fubar then the system will still boot and you can start the recovery process with the backups you should be making all the time?
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linuxgonz
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PostPosted: Thu Sep 12, 2002 5:47 pm    Post subject: Reply with quote

Here is your answer:

I have Gentoo, Mandrake, and WinXP installed in the same hd.

And I'm using gentoo's grub to boot them all, so, I need to have both Mandrake and Gentoo kernels in the same /boot partitions

Mandrake's fstab:

/dev/hda7 / reiserfs...
/dev/hda5 /boot reiserfs...

Gentoo's fstab:

/dev/hda8 / reiserfs...
/dev/hda5 /boot reiserfs...

Get it?
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Naan Yaar
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PostPosted: Thu Sep 12, 2002 5:53 pm    Post subject: Reply with quote

Not really :). Your kernel does not have to live in /boot in order for grub to boot it (cf. the "kernel" setting in grub). Heck, to keep grub happy, you don't even need a grub directory or a boot partition - you can boot from a grub floppy with first and second stages on it directly.
linuxgonz wrote:
Here is your answer:

I have Gentoo, Mandrake, and WinXP installed in the same hd.

And I'm using gentoo's grub to boot them all, so, I need to have both Mandrake and Gentoo kernels in the same /boot partitions

Mandrake's fstab:

/dev/hda7 / reiserfs...
/dev/hda5 /boot reiserfs...

Gentoo's fstab:

/dev/hda8 / reiserfs...
/dev/hda5 /boot reiserfs...

Get it?
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pizen
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PostPosted: Thu Sep 12, 2002 6:03 pm    Post subject: Reply with quote

Naan Yaar wrote:
If you are going to back-ups, it is probably better to assume that the whole drive is toast. Anyway, if modules are in "/", having /boot intact may not leave you in a bootable state. Besides, booting from the install disk or recovery disk should be OK to restore the system.


This is true. Why back up / when you can back up everything? If you aren't using modules then you computer should be bootable. The problem is that it will be unusable after it boots. "Great, /boot is intact. To bad all my shells were in /usr/bin."
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apokalyptik
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PostPosted: Thu Sep 12, 2002 6:22 pm    Post subject: hmm Reply with quote

i'm glad i'm not the only one who sees this as a kind-of double edged idea...

Usually when you experience data loss or corruption you are 1) using a FS known to fubar data because its being developed or 2) your hardware is giving out...

in case 1) your system is wipe and re-loadable anyways (or you're not thinking your setup through) and in case 2) its likely that the damage is iether global (data meets blender) or localized - in which case if its going to make the system un-bootable it will be random enough not to be able to take any real 'precautions' save maybe a mirrored boot and root and usr... in which case you have a mirror and its STILL not nessecary for the /boot...

and there is always the idea that you have the gentoo bootable cd and a million and one little recovery floppies/cds/distros out on the net to use...
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slais-sysweb
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PostPosted: Thu Sep 12, 2002 8:34 pm    Post subject: Reply with quote

If a module is essential to booting a base system it shouldn't be a module. Use modules for stuff that isn't always needed. It also helps to put /boot on a separate drive.
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PostPosted: Thu Sep 12, 2002 8:53 pm    Post subject: Reply with quote

i used to have three linux setups in a time, redhat, gentoo-1.2, and gentoo-1.4, imagine how would u setup grub or lilo with three /boot 's. so i have one /boot in /dev/hda1 and is shared by those 3 installs. The rest of /dev/hda is for redhat, the same /boot is also used for gentoo installs, with roots in /dev/sdcX and /dev/sddX.
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Naan Yaar
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PostPosted: Thu Sep 12, 2002 9:29 pm    Post subject: Reply with quote

It is actually quite trivial. If you have three /boot directories, all you would need to do is use the menu.lst on one of them to specify the kernel location for boot for the different distributions and kernels.

Having a separate /boot simplifies things somewhat (not greatly) for multiple Linux boots. For a single Gentoo boot, it is questionable as to what benefit it provides, as stated above.
vers_iq wrote:
i used to have three linux setups in a time, redhat, gentoo-1.2, and gentoo-1.4, imagine how would u setup grub or lilo with three /boot 's. ...
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PostPosted: Thu Sep 12, 2002 11:05 pm    Post subject: Reply with quote

Having a separate /boot is essential if your system is installed on a software RAID array, as neither GRUB nor LILO can boot from a RAID array. So for me at least, it was a necessity :D
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apokalyptik
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PostPosted: Fri Sep 13, 2002 3:18 am    Post subject: O.K. Reply with quote

could you expand on that last comment a little bit and maybe tell me about your raid setup?

So it basically comes down to (from what i'm hearing) ease of use for the installation of multiple distrobutions on a single machine... Question: how many distrobutions -- out of the box -- create a /boot/ and of those how many coincide nicely with gentoo (honest question to which i dont offhand have hard facts)
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Naan Yaar
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PostPosted: Fri Sep 13, 2002 4:08 am    Post subject: Reply with quote

LILO does support RAID1 boot, though not RAID5.
amigadave wrote:
Having a separate /boot is essential if your system is installed on a software RAID array, as neither GRUB nor LILO can boot from a RAID array. So for me at least, it was a necessity :D
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apokalyptik
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PostPosted: Fri Sep 13, 2002 4:21 am    Post subject: Reply with quote

and hw raid should be transparent, naturally :)
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PostPosted: Fri Sep 13, 2002 8:41 am    Post subject: Reply with quote

Sorry, I don't think I was very clear about my setup (late at night and very tired). I'm using Linux's software RAID-5 for my root partition, which means that my /boot partition needs to be 'not-RAID' so that GRUB can read off the HD when booting. My friend uses software RAID-0 and so he also needs to have a separate /boot partition.
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Naan Yaar
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PostPosted: Fri Sep 13, 2002 1:51 pm    Post subject: Reply with quote

You can use RAID1 for /boot if you are using LILO.

To be clear, I was not suggesting that there were no situations where you needed a separate /boot, but merely that the reason suggested in the Gentoo doc. did not convince me.
amigadave wrote:
...I'm using Linux's software RAID-5 for my root
partition, which means that my /boot partition needs to be 'not-RAID' so that GRUB can read off the HD when booting....
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