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Re: How to Boot with LVM

On Monday, September 7, 2015 at 3:40:05 AM UTC-5, Pascal Hambourg wrote:
> ray a écrit :
> > 
> > AMD64 32G RAM
> > sda, sdb 32GB + 32GB, RAID0 - md0, LVM, GParted shows 1MB reserved, 1 GB (EFI)
> > sdc, sdd 64GB + 64GB, RAID0- md1, md127, LVM, GParted shows 1MB reserved, 1 GB (EFI)
> > sde, sdf 120GB + 120GB, RAID0- md0, md126 LVM, GParted shows 1MB reserved, 1 GB (EFI)
>                                 ^^^^^
> I guess you mean md2 ?
Yes, you are correct, md2.
> > sdg, sdh are 2 and 4 GB HD, sdg currently hosts debian8.+q++q
>                       ^^^^
> I guess you mean TB ? Hard to find 4 GB hard disks these days.
Yes, you are correct, TB.
> > md0-2 form a vg for the new debian8 as dom0 for a xen instance, md127
> > is a vg, md126 is a vg.  md127 & 126 are for swap files.
> Why use separate VGs for swaps ? Performance issues ?
Yes, I chose VGs on two different RAID0 to minimize risk of swap bottle necks, and moved them off of the installation RAID0 volume.  I don't know that it will be a problem on this machine but it was easy to architect a mitigation and I have had this problem on all my other workstations.  
> > gdisk reports that the sda and sdb have gpt partitions.
> You also report that they contain an EFI system partition. This is
> required for booting a disk in UEFI mode (as opposed to legacy BIOS
> mode, which benefits from a BIOS boot partition instead). If the system
> boots in BIOS/legacy mode instead of native UEFI mode, you should
> convert the EFI system partition into a BIOS boot partition or create a
> BIOS boot partition in the 1 MB reserved space.
> Did the Debian installer boot in EFI or BIOS/legacy mode ?
> You can see it in different ways.
> In BIOS mode :
> - it displays the usual well known boot screen from ISOLinux
> - assisted mode using the whole GPT disk creates a BIOS boot partition
> - the "BIOS boot" partition type is available in manual mode on GPT disks
> - in expert mode, GRUB (grub-pc) and LILO are available as the
> bootloader and the installer prompts for the boot device
> In UEFI mode :
> - it displays a different boot screen from GRUB
> - assisted mode using the whole disk creates an EFI system partition
> mounted on /boot/efi
> - the "EFI system" partition type is available in manual mode
> - even in expert mode, only GRUB (grub-efi) is available as the
> bootloader and the installer does not prompts for the boot device.
The motherboard BIOS reports the Debian installation media as a UEFI USB.  
The installer boot screen says UEFI and it is the same media used on the harddisk.  
> What is the boot mode of the already installed system ?
> > I have attempted again to install a new debian8 on the LVM on RAID0
> > for sda&b. I learned more about using the installer for portioning so I
> > was able to get /boot on a RAID0 partition (outside of the vg).  
> If the installer booted in BIOS mode, what did you select as the boot
> device during GRUB installation ?
It installed in UEFI mode.
> > On rebooting, nothing would boot.  The screen message said to insert
> > the media to boot from.
> So the firmware does not see a boot disk. Did you remove the harddisks
> containing the existing Debian installation ?
The harddisks have not been changed.  This is my second round.  Before I set up the RAID, I had a Debian instance on the HD that worked fine and when I installed a new instance on the SSD, neither would boot.

So I rebuilt the HD instance, ran it to configure the SSDs, and again, when installing to the SSDs, nothing will boot.

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