At 03:58 PM 8/16/2005 -0400, Jerry Feldman wrote:

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On Tuesday 16 August 2005 3:12 pm, Shriramana Sharma wrote:

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When I installed SuSE 9.3, I created a swap partition /dev/sda7. When I installed Fedora Core 4, I created a swap partition /dev/sda12.

Is it okay if I edit fstab in both SuSE and FC4 to load both these partitions as swap? (Currently IIRC SuSE uses only /dev/sda7 and FC4 uses only /dev/sda12.)

The contents of a swap partition are emptied at shutdown, right? So when I startup another OS which can use the same partition for swap it will not cause any problems, right?

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If the contents of a swap partition are emptied at bootup instead, then even if the previous shutdown was faulty (power off without unmount or something like that) then the swap partition can still be accessed.

You should have no problems using both swap partitions in your dual boot scenario. The contents of the swap file are essentially cleared during the initial boot into multi-user mode. Any leftover garbage from a previous session is ignored. Essentially, swap space is used for virtual memory pages that have been evicted from physical memory. --

I have a feeling that the question being answered is not the question that might have been intended, to wit: "How can I use _one_ swap partition for two OS's? Particularly when each OS uses a different designation for the partition." --doug -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.338 / Virus Database: 267.10.10/73 - Release Date: 8/15/2005

Patrick Shanahan wrote:

fact: the same swap partition can be used for *all* your linux/*nix OS'es as long as only one is active at a time.

"Only one is active" means only one OS or one swap? I assume it's the former, since others have said that two swaps is not a problem. Now then: does even the *possibility* exist that two OSs are active at a time? (Does this thing called XEN have something to do with running multiple OSs at the same time or just on the same machine?) -- Shriramana Sharma http://samvit.org (o- Penguin #395953 //\ running on ancient Indian wisdom V_/_ and modern computing efficiency

Greg Wallace wrote:

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When I installed SuSE 9.3, I created a swap partition /dev/sda7. installed Fedora Core 4, I created a swap partition /dev/sda12.

Is it okay if I edit fstab in both SuSE and FC4 to load both these partitions as swap?

Are you saying you're wanting to have the same swap(s) active in two os's simultaneously? I wouldn't think you'd want to try that. Anyone else out there doing that?

Two OSs cannot run simultaneously, AFAIK. Maybe this is possible with Xen. Wikipedia says: %--- Xen is an open source virtual machine monitor, or hypervisor, ... It has a design goal of being able to run 100 full featured OS instances on a single typical computer. %--- So possibly this XEN would enable one run many OSs at the same time on a single computer. But if I do that (which I will probably never need to) I understand that it's not a good idea to use the same swap partition for two OSs. The potentiality for conflict is high. And my question was (please re-read the original post included above): I have two partitions on my harddisk which are formatted as Linux-swap. I do not run two OSs simultaneously (which means "at the same instant of time") though I have them installed on my machine. I boot into SuSE, I logout from SuSE, I reboot into Fedora, I logout from Fedora and so on. That's it. Now I wondered if the two swap partitions can both be used by both my installations. If I'm still not clear, I don't know how I can phrase it better. Others have apparently understood my meaning.

Wouldn't you have only 1 swap defined to each OS, meaning even if they ran at the same time, they'd be hitting different partitions?

Right. If I ever used XEN to run my two Linuxes at the same time, I would point SuSE to /dev/sda7 and FC4 to /dev/sda12. -- Shriramana Sharma http://samvit.org (o- Penguin #395953 //\ running on ancient Indian wisdom V_/_ and modern computing efficiency

On Wednesday 17 August 2005 4:26 am, Shriramana Sharma wrote:

Two OSs cannot run simultaneously, VMWare, Xen and other virtualization solutions make it possible for multiple OS's to run simultaneously, but that is not the way you have your system set up. In a multi-boot situation where you boot up separately, you can share the swap areas between the OS's.

-- Jerry Feldman Boston Linux and Unix user group http://www.blu.org PGP key id:C5061EA9 PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9

On Wed, 2005-08-17 at 13:56 +0530, Shriramana Sharma wrote:

Greg Wallace wrote:

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When I installed SuSE 9.3, I created a swap partition /dev/sda7. installed Fedora Core 4, I created a swap partition /dev/sda12.

Is it okay if I edit fstab in both SuSE and FC4 to load both these partitions as swap?

Are you saying you're wanting to have the same swap(s) active in two os's simultaneously? I wouldn't think you'd want to try that. Anyone else out there doing that?

Two OSs cannot run simultaneously, AFAIK. Maybe this is possible with Xen. Wikipedia says:

What is VM then? Is it only a paging system which puts the others to sleep? -- o o o o o oo o o o o _______________________________ o _____ | CWSIV@PCMAGIC.NET | .][__n_n_|DD[ ====_____ | M A R K L I N T R A I N S | > (________|__|_[_________]_|___________________________| _/oo OOOOO oo` ooo ooo 'o!o!o o!o!o` Steaming over the bodys of liberals, democrats and mental midgets.

On 8/21/05, Greg Wallace wrote:

I suspect you wouldn't be using it if you are letting VM manage your VIO.

May I know what VIO means, please?

Greg Wallace wrote:

Wouldn't you have only 1 swap defined to each OS, meaning even if they ran at the same time, they'd be hitting different partitions?

Why bother? Also, how do you get two OSs to run at the same time (other than virtual machines)?

On Tuesday, August 16, 2005 @ 6:21 PM, Shriramana Sharma wrote:

Thanks to all who replied.

Doug McGarrett wrote:

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When I installed SuSE 9.3, I created a swap partition /dev/sda7. When I installed Fedora Core 4, I created a swap partition /dev/sda12.

Is it okay if I edit fstab in both SuSE and FC4 to load both these partitions as swap?

I have a feeling that the question being answered is not the question that might have been intended, to wit: "How can I use _one_ swap partition for two OS's? Particularly when each OS uses a different designation for the partition."

No, the question was answered correctly. Please see my original question above. I said that I have two swap partitions on my sda and wish to use both these for both my Linuxes.

Thanks to you and Patrick for the related thought, anyway... :)

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Shriramana Sharma http://samvit.org

(o- Penguin #395953 //\ running on ancient Indian wisdom V_/_ and modern computing efficiency

Are you saying you're wanting to have the same swap(s) active in two os's simultaneously? I wouldn't think you'd want to try that. Anyone else out there doing that? Greg Wallace

Jerry Feldman wrote:

The contents of the swap file are essentially cleared during the initial boot into multi-user mode. Any leftover garbage from a previous session is ignored.

You mean, the OS doesn't care if any garbage is left-over from a previous session but clears (without warning) the contents of the swap file, right? -- Shriramana Sharma http://samvit.org (o- Penguin #395953 //\ running on ancient Indian wisdom V_/_ and modern computing efficiency

On Tuesday 16 August 2005 10:22 pm, Shriramana Sharma wrote:

Jerry Feldman wrote:

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The contents of the swap file are essentially cleared during the initial boot into multi-user mode. Any leftover garbage from a previous session is ignored.

You mean, the OS doesn't care if any garbage is left-over from a previous session but clears (without warning) the contents of the swap file, right? Yes. It actually does not clear the contents. The OS (via hardware/software) keeps track of memory pages. When it needs to evict a page to swap, it writes that out to the swap area. So, the OS always knows the status of every page that is stored in swap.

-- Jerry Feldman Boston Linux and Unix user group http://www.blu.org PGP key id:C5061EA9 PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9