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#1 2012-11-13 21:30:02

ClaudioP
Member
From: Portugal
Registered: 2012-03-11
Posts: 59

Multiple computers running from one hard drive?

I got in my school some computers free in the class, can i boot up one computer from an external HDD(as i normally do), and then when i need more resources make a computer do "network boot" to boot from the same disk(maybe another partition) as another operating system is working?
Sorry, the English is bad and the question its even worst, i just want to know if i can in the real world use arch to make this to have two or more computers working at the same time, sharing the hard drive.
Imagination working... possible? tongue


Ahh... stuff

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#2 2012-11-13 22:08:44

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 12,265

Re: Multiple computers running from one hard drive?

Yes, but it is non-trivial

You might look at https://wiki.archlinux.org/index.php/PXE


Executive summary:

In general,  The workstations will want to use boot using PXE.
Your server will be configured as a DHCP server and will tell the hosts that connect to it where to find a TFTP server which will contain the Linux kernel the will be using.
Your server will also be configured as the TFTP server referred to above.  It will serve files to the clients during boot.
Your server will also be configured as a NFS server.  The files served by the TFTP server includes a /etc/fstab that direct the system to mount NFS volumes.


Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Like you, I have no idea what you are doing, but I am pretty sure it is wrong...Jasonwryan
----
How to Ask Questions the Smart Way

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#3 2012-11-13 22:17:50

ClaudioP
Member
From: Portugal
Registered: 2012-03-11
Posts: 59

Re: Multiple computers running from one hard drive?

ewaller wrote:

Yes, but it is non-trivial

You might look at https://wiki.archlinux.org/index.php/PXE


Executive summary:

In general,  The workstations will want to use boot using PXE.
Your server will be configured as a DHCP server and will tell the hosts that connect to it where to find a TFTP server which will contain the Linux kernel the will be using.
Your server will also be configured as the TFTP server referred to above.  It will serve files to the clients during boot.
Your server will also be configured as a NFS server.  The files served by the TFTP server includes a /etc/fstab that direct the system to mount NFS volumes.

I already saw the page you referenced but as it's written "allows you to boot the installation media using a network interface", i thought that it allows reading but not writing.
I never configured(successfully) none of the servers you said, how hard it is to do everything?

Just curious: You said workstations... doesn't a workstation normally needs very fast disk access? Isn't that a bottleneck?

Thanks for your answer


Ahh... stuff

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#4 2012-11-13 22:37:54

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 12,265

Re: Multiple computers running from one hard drive?

When I say workstation, I mean one of the computers that does not have a disk and are sharing the one on the server.
The boot image read only, but when the kernel starts, it mounts a NFS volume on /.  That NFS volume can be read/write.

It is not that hard to set up, but it can be confusing.  I went back and read the article I linked, and you are right; its emphasis is on installing Arch.  Try this (non-Arch) link:
http://www.digitalpeer.com/id/linuxnfs
for a different explanation.


edit: Also, try http://www.ibiblio.org/pub/Linux/docs/H … HOWTO.html which was linked from the other article I linked.

Last edited by ewaller (2012-11-13 22:39:41)


Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Like you, I have no idea what you are doing, but I am pretty sure it is wrong...Jasonwryan
----
How to Ask Questions the Smart Way

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#5 2012-11-14 01:23:42

hiciu
Member
Registered: 2010-08-11
Posts: 77

Re: Multiple computers running from one hard drive?

I'm not sure if I understand what you need but you can boot slax from one livecd / one usb stick on many computers using PXE. With enough memory (2GB is enough) it can keep everything in ram.

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#6 2012-11-15 02:38:07

nomorewindows
Member
Registered: 2010-04-03
Posts: 2,944

Re: Multiple computers running from one hard drive?

Just make sure your NFS export is rw.
I usually stuff the NFS export underneath the tftp directory.  It is flexible enough to actually be located on another server, but hence for small work it's nice to manage under one place.

I think they are trying to merge the PXE wiki with the NFS diskless wiki, might give the diskless wiki a look.
One problem that was still with the diskless wiki is it was using an older tftp, and using xinetd to control it.  The xinetd part is 10 years ago.

Last edited by nomorewindows (2012-11-15 02:40:09)


I may have to CONSOLE you about your usage of ridiculously easy graphical interfaces...
Look ma, no mouse.

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#7 2012-11-15 11:29:28

ClaudioP
Member
From: Portugal
Registered: 2012-03-11
Posts: 59

Re: Multiple computers running from one hard drive?

ewaller wrote:

When I say workstation, I mean one of the computers that does not have a disk and are sharing the one on the server.
The boot image read only, but when the kernel starts, it mounts a NFS volume on /.  That NFS volume can be read/write.

It is not that hard to set up, but it can be confusing.  I went back and read the article I linked, and you are right; its emphasis is on installing Arch.  Try this (non-Arch) link:
http://www.digitalpeer.com/id/linuxnfs
for a different explanation.


edit: Also, try http://www.ibiblio.org/pub/Linux/docs/H … HOWTO.html which was linked from the other article I linked.

Each tutorial does the same thing in a different way... yet, my "newbieness" isn't enough to do any(yet).
How does the guest computer knows what is the right DHCP server? Broadcasts and waits for the first response?
I tried to set a virtualbox host-only network environment and it found the host DHCP server, but in the real network i always went to the router PXE.

hiciu wrote:

I'm not sure if I understand what you need but you can boot slax from one livecd / one usb stick on many computers using PXE. With enough memory (2GB is enough) it can keep everything in ram.

I don't want to run a LiveCD, i want to run a real machine. I know that it is slow to read/write, but the tasks i have to do are not disk-intensive.

nomorewindows wrote:

Just make sure your NFS export is rw.
I usually stuff the NFS export underneath the tftp directory.  It is flexible enough to actually be located on another server, but hence for small work it's nice to manage under one place.

I think they are trying to merge the PXE wiki with the NFS diskless wiki, might give the diskless wiki a look.
One problem that was still with the diskless wiki is it was using an older tftp, and using xinetd to control it.  The xinetd part is 10 years ago.

Thanks for your suggestion. I think that (after finding how to boot from the correct pxe server) i just need to configure the paths and the NFS server.
Why are things so hard to do in the first time?!? tongue

Thanks for your helpful posts


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