Arch Linux

jglazner

Member

Registered: 2011-08-01

Posts: 3

Installing an Arch VM under Xen shows 2 devices as /dev/sda

Hey guys, I'm pretty new to arch, I have it installed on my desktop, and my laptop and so far I love it.  I am running into a problem though getting it installed on my shared server.  I share a server with my uncle who refuses to use KVM so i'm stuck using the xen stuff.  The problem I'm having is at the very end of the installation when i'm asked where to install the boot loader.  Normally this is a no brainer and I just choose /dev/sda but in this case my installer shows 2 devices with that label.  I've tried using the auto setup, manual setup it doesn't seem to matter I always end up with 2 devices for /dev/sda on this screen.  I've tried installing the bootloader to each one but it seems to brick it and dumps me into the emergency recovery when I restart.  When I do an ls of /dev/disk/by-* I only see the cdrom.  I just don't know what else to do.  To be thorough I've listed all the devices shown in the /dev under the different paths as well as what I see in the install window:

This is what I see during the bootloader install section:
/dev/sda
/dev/sda
/dev/sda1 (this is my swap)
/dev/sda2 (this is ext4 mounted to / and is the bootable partition)
/dev/sda3 (this is ext4 mounted to /home)

Switching to virtual console to poke around:

Looking at where grub thinks root is:
#grub
find /boot/grub/stage1
  (hd0,1)

What devices show under /dev?

ls of  /dev | grep sda
sda
sda1
sda2
sda3

ls of /dev/disk/by-id:
ata-QEMU_HARDDISK_QM000001
ata-QEMU_HARDDISK_QM000001-part1
ata-QEMU_HARDDISK_QM000001-part2
ata-QEMU_HARDDISK_QM000001-part3
scsi-SATA_QEMU_HARDDISK_QM000001
scsi-SATA_QEMU_HARDDISK_QM000001-part1
scsi-SATA_QEMU_HARDDISK_QM000001-part2
scsi-SATA_QEMU_HARDDISK_QM000001-part3

ls of /dev/disk/by-path:
pci-0000:00:01.1-scsi-0:0:0:0
pci-0000:00:01.1-scsi-0:0:0:0-part1
pci-0000:00:01.1-scsi-0:0:0:0-part2
pci-0000:00:01.1-scsi-0:0:0:0-part3
pci-0000:00:01.1-scsi-1:0:0:0

ls of /dev/disk/by-uuid:
1146795e-f98d-4890-9ead-af8081dc05e3
57e493d8-3907-4416-a1a3-0ff441ba87c1
6764ec91-f29f-4488-961f-4c5dc09a138b

AFTER RESTART:
ls of /dev/disk/by-id:
ata-QEMU_CD-ROM_QM00003

ls of /dev/disk/by-path/:
pci-0000:00:01.1-scsi-1:0:0:0

ls of /dev/disk/by-uuid:
ls: /dev/disk/by-uuid: No such file or directory

alphaniner

Member

From: Ancapistan

Registered: 2010-07-12

Posts: 2,810

Re: Installing an Arch VM under Xen shows 2 devices as /dev/sda

I just reinstalled on a physical machine and saw two copies of every sd device. It looked something like

/dev/sda
/dev/sdb
/dev/sdc
/dev/sda
<sda partitions>
/dev/sdb
<sdb partitions>
/dev/sdc
<sdc partitions>

I assumed that was a 'feature' since grub is normally installed to MBR. I chose the first instance of the appropriate entry (/dev/sda) and haven't had any issues. If it's showing up for just one drive, it probably is a bug.

That said, I doub't it's related to the real problem you're having.

Last edited by alphaniner (2011-08-01 19:21:00)

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But whether the Constitution really be one thing, or another, this much is certain - that it has either authorized such a government as we have had, or has been powerless to prevent it. In either case, it is unfit to exist.
-Lysander Spooner

jglazner

Member

Registered: 2011-08-01

Posts: 3

Re: Installing an Arch VM under Xen shows 2 devices as /dev/sda

Yeah, the real underlying problem is that the /dev/sda dissappears after the install.  What's weird is if i boot back to the iso image, sda shows up with all the partitions I created during the install. So why does the installer see the drives?  Is this a grub issue? 

Jed.

alphaniner

Member

From: Ancapistan

Registered: 2010-07-12

Posts: 2,810

Re: Installing an Arch VM under Xen shows 2 devices as /dev/sda

Is it possible you didn't properly configure mkinitcpio.conf and your ramdisk is missing something?  Have you tried the fallback boot option?

---

But whether the Constitution really be one thing, or another, this much is certain - that it has either authorized such a government as we have had, or has been powerless to prevent it. In either case, it is unfit to exist.
-Lysander Spooner

jglazner

Member

Registered: 2011-08-01

Posts: 3

Re: Installing an Arch VM under Xen shows 2 devices as /dev/sda

The config looked right, and the backup image failed also.  I'm beginning to wonder if this is a xen thing.  I tried installing a different guest distro and it also seemed to install fine, but failed to find /dev/sda after reboot.  These are fully virtualized guests, so i shouldn't need to patch the kernel right?

alphaniner

Member

From: Ancapistan

Registered: 2010-07-12

Posts: 2,810

Re: Installing an Arch VM under Xen shows 2 devices as /dev/sda

I've used XenServer but I know very little about plain ol' Xen.  I think it can use both paravirt. and hardware-assisted (full) virt, the latter requiring VT-x or AMD-V .  Maybe check and make sure everything (including the VM itself?) is setup for full virt.

---

But whether the Constitution really be one thing, or another, this much is certain - that it has either authorized such a government as we have had, or has been powerless to prevent it. In either case, it is unfit to exist.
-Lysander Spooner