LVM partitions on ax external USB HD
Antonio Montagnani
anto.montagnani at virgilio.it
Sat Apr 16 14:04:09 UTC 2005
-------- Original Message --------
Subject: Re: LVM partitions on ax external USB HD
Date: Sat, 16 Apr 2005 12:40:57 +0200
From: Antonio Montagnani <anto.montagnani at virgilio.it>
To: ja <ja at ee.port.ac.uk>
References: <4258E526.2040307 at virgilio.it>
<200504111653.18230.wagnerric at condor.cxo.cpqcorp.net>
<425B7743.4010903 at virgilio.it>
<1113300463.23772.1.camel at maui.jaa.org.uk>
<425FCCB2.5020907 at virgilio.it> <1113583468.8863.70.camel at maui.jaa.org.uk>
ja wrote / ha scritto on /il 15/04/2005 18:44:
>On Fri, 2005-04-15 at 16:16 +0200, Antonio Montagnani wrote:
>
>
>>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???
>>
>>
>>
>>
>
>Hi Antonio
>You would have to regenerate the CD with a fixed grub.conf which is not
>that clever.
>The generation of the CD is relatively easy but
>unless anyone knows different then there is no flexibility.
>
>I would not give up on the booting from USB disk yet !!!!
>What does it actually do ????
>1. Boot from other disk
>2. Not boot at all
>3. Give a grub> prompt
>4. ...
>
>Let me know
>######################################
>Try the CD if you can
>
>Try another laptop/desktop machine with and without CD
>######################################
>I'm still not 100% sure you have grub things written
>to the USB MBR
>
>Other questions
>a. Will the USB disk mount when plugged into a running Linux machine
>b If so are /boot and /boot/grub directories correct?
>######################################
>With the USB disk plugged into a working Linux machine
>
>You could try (very carefully) as root
>cd
>dd if=/dev/sd??? of=usb_first_446.dd bs=446 count=1
>
>where /dev/sd??? is your USB disk
>This reads the first 446 bytes from the disk to a file
>if=xxx stands for input file, of=yyy stands for output file
>bs=block size, count=No of blocks
>
>There are no "-" signs in front of the command line "options" !
>It is then possible to tell if grub things are there !!!!
>Be VERY CAREFUL with dd getting it wrong could write nasty things to
>the MBR on your other disk!!!!!
>Send me the usb_first_446.dd file or the result of
>od -bc usb_first_446.dd
>
>If this file looks like it has grub type things in it
>then I think your BIOS is not doing things correctly.
>
>Lots of things to try !!!!
>Good luck - again !!!!
>
>john
>
>
>
>
>
Hello
mad esome tests.
1) created CD from your iso. Booted with grub commands using
initrd=(hd1,0)/initrd_usb.gz
and Fedora started.
Now I attach the usb_first_446.dd file, as We all have doubt that grub
is installed on USB disk.
Tnx for your super-help!!!
--
Antonio
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Antonio
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