LVM partitions on ax external USB HD

[Antonio Montagnani]

John Austin wrote / ha scritto on /il 12/04/2005 12:07:

>On Tue, 2005-04-12 at 09:22 +0200, Antonio Montagnani wrote:
>  
>
>>Rick Wagner ha scritto / wrote  il / on 12/04/2005 00:53:
>>
>>    
>>
>>>On Sunday 10 April 2005 2:34 am, Antonio Montagnani wrote:
>>> 
>>>
>>>      
>>>
>>>>I tried to install Fedora on an external USB HD.
>>>>Of course booting from it didn't work.
>>>>On the disk there are an ext3 partition /boot and a LVM partition
>>>>If I connect the HD to a PC as USB device it is correctly mounted but I
>>>>see only the ext3 partition.
>>>>How can I see also the LVM???
>>>>        
>>>>
>
>  
>
>>>Since no one else has answered, I'll take a stab.  I have used LVM on several 
>>>permanent hard drives, but never on removables.  However I think what your 
>>>looking to do is a udev script.  Check out the information on udev.  Also 
>>>look for hotplug.  
>>>
>>>What you'll want your script to do is upon detecting the plugging of your USB 
>>>drive, it will want to scan (vgscan/lvscan) the drive for LVM volumes, then 
>>>activate the volume (vgchange/lvchange --available=yes).
>>>
>>>I'm not sure what you want to do for unplugging.  I expect that you'll need a 
>>>script to flush then deactivate the volumes prior to pulling the plug on the 
>>>drive.
>>>
>>>As I said, I don't know much about hotplug and udev, but this may give you 
>>>some additional search hints.
>>>
>>>	--rick
>>>      
>>>
>
>  
>
>>Rick,
>>
>>Tnx for you reply.
>>
>>There are two separate issues:
>>
>>1) how to manage a LVM partitioned removable device (USB hard disk, key 
>>etc.): does it make any sense to have them partitioned as LVM??
>>2) how to install Fedora on a removable device (USB hard disk, for 
>>example) and boot off it (with Grub installed on it, in order to have a 
>>removable Fedora installation for every occasion)
>>
>>I have not enough skill to solve them. Any idea??
>>
>>-- 
>>Antonio M.
>>    
>>
>Hi
>I may be able to help with the second question
>I have a pdf document which I can email direct if you want
>Let me know
>John
>
>
>  
>
>>================================================================================
>>    
>>
>
>  
>
John, your server bounces me back as spammer!!!! I have an e-mail about 
this subject.

Please read the following :

 >> Hi John,
 >>
 >> I have followed all instructions (that are very clear, Tnx a lot), 
but after Grub installation, I re-booted the laptop, but It didn't start 
from USB removable device!!! and is supports it (As from BIOS and from 
manual: never tried to start by USB devices before this installation)
 >> I unplugged also the USB drive lead and re-plugged while booting.No 
way of USB booting.
 >> Any suggestion??
 >> This afternoon I will plug the USB disk to another PC to see what 
happens.Please note that my USB disk is an EIDE disk inside an EIDE to 
USB metallic box.
 >>
 >> Cheers
 >>
 >>  
 >
 > Hi Antonio
 >
 > First question did you get a grub> prompt ??
 >
 > I am assuming NOT !
 >
 > This next bit is going to be added to the pdf doc sometime!!!!
 > 
 >
I followed your paper (the only difference was different order of sda 
for /boot(sda1), /(sda2), swap (sda3), but I changed related 
references): and I arrived very smoothly to exit instruction at end of 
point 3.3.5, but I couldn't reboot. I also re-plugged the USB disk 
during boot but no way (see 3.3.6)

 > Its not ideal but should get you up and booted on the USB without
 > touching any other disk.  It will also help to test if all is well on
 > the USB disk
 > This does assume you have access to a Linux box to write a floppy and/or
 > a CD
 > ##################################33
 > I have an Icybox USB2/SATA to PATA box with an old IDE disk in it which
 > works fine, so that is probably not a problem
 > ######################################
 > If you have a floppy drive on your machine you can use it to boot grub.
 > 
 >
No floppy available

 > I attach a floppy image that you can write to a blank
 > floppy as follows
 > dd of=/dev/fd0 if=fd0_grub.img
 > Then set the BIOS to boot from floppy
 > You should then get a raw grub prompt to type in
 > something like
 > grub>kernel (hdx,y)/vmlinuz..  ro  root=/dev/hdpq
 > grub>initrd (hdx,y)/initrd... (the original one not the USB )
 > grub>boot
 >
 > Obviously you should also be able to see if the initrd_usb.gz is there
 > etc
 > ###############################
 > If your machine has no floppy then I also attach a raw bootable ISO CD
 > image.  It has nothing on it except an image of the floppy.
 > It should boot OK and give the grub> prompt just as the floppy.
 > I used xcdroast to write the image.iso file to CD
 >
 > Also tested out direct use of cdrecord
 > cdrecord -scanbus
 > will show cd/dvd devices
 >
 > cdrecord dev=ATAPI:1,0,0 speed=8 image.iso
 > ATAPI: may not be necessary depending how your cd/dvd is treated
 > 1,0,0 to match the output of -scanbus above
 > No problems
 >
 > When booting from CD BIOS understanding of the disks
 > and that of Linux may not be the same as booting from USB !!!
 > Finding how grub sees the devices is easy
 > kernel (hdTAB     etc
 >
 > The value needed by root=/dev/sdXX may require trial
 > and error !!!!
 > 
 >
If I succeed to start interactively by CD, if I write a 
/boot/grub/grub.conf, should I be able to start up by same CD???
I suppose that if I connect same USB disk to another laptop, chances of 
insuccess are great....what do you think???


-- 
 Antonio
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